{ "pdf_info": [ { "para_blocks": [ { "bbox": [ 86, 112, 189, 131 ], "type": "title", "angle": 0, "index": 0, "lines": [ { "bbox": [ 86, 111, 191, 133 ], "spans": [ { "bbox": [ 86, 111, 191, 133 ], "type": "text", "content": "什么是 Shell？", "score": 1.0 } ] } ] }, { "bbox": [ 86, 168, 189, 181 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 169, 189, 181 ], "spans": [ { "bbox": [ 89, 169, 189, 181 ], "type": "text", "content": "是一种程序设计语言。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 184, 504, 212 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 185, 504, 196 ], "spans": [ { "bbox": [ 89, 185, 504, 196 ], "type": "text", "content": "Shell 是指一种应用程序，这个应用程序提供了一个界面，用户通过这个界面访问操作系统", "score": 1.0 } ] }, { "bbox": [ 89, 200, 148, 213 ], "spans": [ { "bbox": [ 89, 200, 148, 213 ], "type": "text", "content": "内核的服务。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 215, 504, 243 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 214, 506, 230 ], "spans": [ { "bbox": [ 88, 214, 506, 230 ], "type": "text", "content": "Bash（GNU Bourne-Again Shell）是一个为 GNU 计划编写的 Unix shell，它是许多", "score": 1.0 } ] }, { "bbox": [ 88, 230, 223, 245 ], "spans": [ { "bbox": [ 88, 230, 223, 245 ], "type": "text", "content": "Linux 平台默认使用的 shell。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 246, 504, 306 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 247, 504, 259 ], "spans": [ { "bbox": [ 88, 247, 504, 259 ], "type": "text", "content": "shell 是一个命令解释器，是介于操作系统内核与用户之间的一个接口层。它也是一种能力", "score": 1.0 } ] }, { "bbox": [ 89, 263, 505, 275 ], "spans": [ { "bbox": [ 89, 263, 505, 275 ], "type": "text", "content": "很强的计算机语言，被称为解释性语言或脚本语言 script。可以通过将系统调用、公共程", "score": 1.0 } ] }, { "bbox": [ 89, 278, 505, 290 ], "spans": [ { "bbox": [ 89, 278, 505, 290 ], "type": "text", "content": "序、工具和编译过的二进制程序“粘合”在一起来建立应用，这是大多数脚本语言的共同", "score": 1.0 } ] }, { "bbox": [ 88, 294, 296, 306 ], "spans": [ { "bbox": [ 88, 294, 296, 306 ], "type": "text", "content": "特征，所以脚本语言又被称为“胶水语言”。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 308, 505, 354 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 310, 505, 322 ], "spans": [ { "bbox": [ 89, 310, 505, 322 ], "type": "text", "content": "Shell是系统的用户界面，提供了用户与内核进行交互操作的一种接口(命令解释器) 。它接", "score": 1.0 } ] }, { "bbox": [ 89, 326, 505, 337 ], "spans": [ { "bbox": [ 89, 326, 505, 337 ], "type": "text", "content": "收用户输入的命令并把它送入内核去执行。起着协调用户与系统的一致性和在用户与系统", "score": 1.0 } ] }, { "bbox": [ 88, 340, 466, 354 ], "spans": [ { "bbox": [ 88, 340, 104, 354 ], "type": "text", "content": "之", "score": 1.0 }, { "bbox": [ 127, 340, 145, 354 ], "type": "text", "content": "间", "score": 1.0 }, { "bbox": [ 169, 340, 186, 354 ], "type": "text", "content": "进", "score": 1.0 }, { "bbox": [ 210, 340, 227, 354 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 252, 340, 268, 354 ], "type": "text", "content": "交", "score": 1.0 }, { "bbox": [ 287, 340, 312, 354 ], "type": "text", "content": "互", "score": 1.0 }, { "bbox": [ 334, 340, 351, 354 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 376, 340, 392, 354 ], "type": "text", "content": "作", "score": 1.0 }, { "bbox": [ 417, 340, 432, 354 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 460, 346, 466, 354 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "type": "image", "bbox": [ 88, 356, 376, 502 ], "blocks": [ { "bbox": [ 88, 356, 376, 502 ], "lines": [ { "bbox": [ 88, 356, 376, 502 ], "spans": [ { "bbox": [ 88, 356, 376, 502 ], "type": "image", "image_path": "2f1fbe30e5df1933f987b31f395caca2a97bb40a4f308e9039adf97eb01bcfc5.jpg" } ] } ], "index": 6, "angle": 0, "type": "image_body" } ], "index": 6 }, { "bbox": [ 86, 511, 470, 524 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 511, 471, 527 ], "spans": [ { "bbox": [ 88, 511, 471, 527 ], "type": "text", "content": "Python、PHP、Perl、javascript 等都是脚本语言，解释执行，有相似的基本特征。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 527, 508, 539 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 527, 511, 541 ], "spans": [ { "bbox": [ 88, 527, 511, 541 ], "type": "text", "content": "事实上，所有的 UNIX 命令和工具再加上公共程序，对于 shell 脚本来说，都是可调用的。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 542, 505, 571 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 543, 505, 555 ], "spans": [ { "bbox": [ 88, 543, 505, 555 ], "type": "text", "content": "Shell 脚本对于实现管理系统任务的自动化和执行其它重复性工作来说，非常适合，灵活强", "score": 1.0 } ] }, { "bbox": [ 89, 559, 263, 571 ], "spans": [ { "bbox": [ 89, 559, 263, 571 ], "type": "text", "content": "大，比编写编译型程序更加高效灵活。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 573, 505, 650 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 574, 506, 587 ], "spans": [ { "bbox": [ 88, 574, 506, 587 ], "type": "text", "content": "内 置 命 令 ： 出 于 效 率 的 考 虑 ， 将 一 些 常 用 命 令 的 解 释 程 序 构 造 在 Shell 内 部", "score": 1.0 } ] }, { "bbox": [ 88, 589, 506, 602 ], "spans": [ { "bbox": [ 88, 589, 506, 602 ], "type": "text", "content": "外 置 命 令 ： 存 放 在 /bin 、 /sbin 目 录 下 的 命 令", "score": 1.0 } ] }, { "bbox": [ 88, 604, 506, 618 ], "spans": [ { "bbox": [ 88, 604, 506, 618 ], "type": "text", "content": "实用程序：存放在/usr/bin、/usr/sbin、/usr/share、/usr/local/bin 等目录下的实用程序", "score": 1.0 } ] }, { "bbox": [ 89, 621, 506, 634 ], "spans": [ { "bbox": [ 89, 621, 506, 634 ], "type": "text", "content": "用 户 程 序 ： 用 户 程 序 经 过 编 译 生 成 可 执 行 文 件 后 ， 可 作 为 Shell 命 令 运 行", "score": 1.0 } ] }, { "bbox": [ 88, 636, 506, 649 ], "spans": [ { "bbox": [ 88, 636, 506, 649 ], "type": "text", "content": "Shell 脚 本 ： 由 Shell 语 言 编 写 的 批 处 理 文 件 ， 可 作 为 Shell 命 令 运 行", "score": 1.0 } ] } ] }, { "bbox": [ 86, 667, 242, 680 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 667, 241, 681 ], "spans": [ { "bbox": [ 89, 667, 241, 681 ], "type": "text", "content": "内部命令、应用程序、shell脚本", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 682, 505, 758 ], "blocks": [ { "bbox": [ 86, 682, 505, 758 ], "lines": [ { "bbox": [ 86, 682, 505, 758 ], "spans": [ { "bbox": [ 86, 682, 505, 758 ], "type": "table", "html": "
命\n命\n通令\n令\n配行\n种\n符解\n执行\n顺序释\nwild-cardcharacters历史I/O
", "image_path": "fbf3225e75a711ea24ea1be2969ee839f31ba26037a31c311c221be798fc41e1.jpg" } ] } ], "index": 12, "angle": 0, "type": "table_body" } ], "index": 12 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 0 }, { "para_blocks": [ { "type": "table", "bbox": [ 87, 77, 500, 124 ], "blocks": [ { "bbox": [ 87, 77, 500, 124 ], "lines": [ { "bbox": [ 87, 77, 500, 124 ], "spans": [ { "bbox": [ 87, 77, 500, 124 ], "type": "table", "html": "
管道pipes(
命令 替 换或 $(或 $()
Shell编 程 语 言ShellScript
", "image_path": "90a01365fbbf634e2472f01e6aa8771cadf377f4ff2e67d1415d7eefe32607fc.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "bbox": [ 88, 141, 163, 154 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 140, 164, 156 ], "spans": [ { "bbox": [ 88, 140, 164, 156 ], "type": "text", "content": "都有哪些 shell？", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 169, 337, 304 ], "blocks": [ { "bbox": [ 88, 169, 337, 304 ], "lines": [ { "bbox": [ 88, 169, 337, 304 ], "spans": [ { "bbox": [ 88, 169, 337, 304 ], "type": "table", "html": "
Bash (Bourne Again Shell)bash是大多数Linux系统的默认Shell。 bash与bash完全向后兼容,并且在bash的基础上增加和增 强了很多特性。 bash也包含了很多C Shell和Korn Shell中的优点。 bash有很灵活和强大的编程接口,同时又有很友好的用 户界面
Ksh (Korn Shell)Korn Shell(ksh)由Dave Korn所写。它是UNIX系统上的 标准Shell。 在Linux环境下有一个专门为Linux系统编写的Korn Shell的 扩展版本,即Public Domain Korn Shell(pdksh)。
tcsh (csh 的扩展)tcsh是C Shell的扩展。tcsh与csh完全向后兼容,但它包 含了更多的使用户感觉方便的新特性,其最大的提高是在 命令行编辑和历史浏览方面
", "image_path": "1a6197dc2e70844015da3351b232066b3b4325449fe1854f6b0463c3e4ea69c4.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "type": "table", "bbox": [ 87, 311, 508, 420 ], "blocks": [ { "bbox": [ 87, 311, 508, 420 ], "lines": [ { "bbox": [ 87, 311, 508, 420 ], "spans": [ { "bbox": [ 87, 311, 508, 420 ], "type": "table", "html": "
(sh、bash、ksh、csh等)
登录login:stu01
password:student01
注意:casesensitive(上限case/lowercase)
提示符#、$
注销exit/login/Ctrl+D
重启动reboot
", "image_path": "01f9555c37c1dbe9c10a9916879a391417f600c77eb93dc5a41135d92258e070.jpg" } ] } ], "index": 3, "angle": 0, "type": "table_body" } ], "index": 3 }, { "bbox": [ 88, 422, 179, 435 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 420, 181, 437 ], "spans": [ { "bbox": [ 88, 420, 181, 437 ], "type": "text", "content": "关闭系统 poweroff", "score": 1.0 } ] } ] }, { "bbox": [ 88, 468, 246, 481 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 469, 246, 482 ], "spans": [ { "bbox": [ 89, 469, 246, 482 ], "type": "text", "content": "查看系统中目前可以使用的shells", "score": 1.0 } ] } ] }, { "bbox": [ 88, 484, 160, 496 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 89, 484, 160, 497 ], "spans": [ { "bbox": [ 89, 484, 160, 497 ], "type": "text", "content": "Cat /etc/shells", "score": 1.0 } ] } ] }, { "bbox": [ 88, 499, 158, 513 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 499, 159, 513 ], "spans": [ { "bbox": [ 88, 499, 159, 513 ], "type": "text", "content": "切换到sh模式", "score": 1.0 } ] } ] }, { "bbox": [ 88, 515, 103, 527 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 87, 515, 104, 530 ], "spans": [ { "bbox": [ 87, 515, 104, 530 ], "type": "text", "content": "Sh", "score": 1.0 } ] } ] }, { "bbox": [ 88, 530, 148, 543 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 530, 149, 544 ], "spans": [ { "bbox": [ 88, 530, 149, 544 ], "type": "text", "content": "推出sh模式", "score": 1.0 } ] } ] }, { "bbox": [ 88, 547, 108, 557 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 546, 110, 560 ], "spans": [ { "bbox": [ 88, 546, 110, 560 ], "type": "text", "content": "exit", "score": 1.0 } ] } ] }, { "bbox": [ 87, 561, 505, 606 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 562, 505, 575 ], "spans": [ { "bbox": [ 89, 562, 505, 575 ], "type": "text", "content": "学习一门语言习惯与先写一个HelloWorld的程序，这里就写一个HelloWorld的脚本。下", "score": 1.0 } ] }, { "bbox": [ 89, 578, 505, 591 ], "spans": [ { "bbox": [ 89, 578, 505, 591 ], "type": "text", "content": "面启动 vim 编辑 hello.sh 脚本文件。后缀名“.sh”不是必须的，但是更容易表示这是一个", "score": 1.0 } ] }, { "bbox": [ 89, 593, 159, 607 ], "spans": [ { "bbox": [ 89, 593, 159, 607 ], "type": "text", "content": "脚本程序文件。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 624, 149, 636 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 88, 624, 149, 638 ], "spans": [ { "bbox": [ 88, 624, 149, 638 ], "type": "text", "content": "vim hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 88, 651, 147, 664 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 88, 652, 148, 665 ], "spans": [ { "bbox": [ 88, 652, 148, 665 ], "type": "text", "content": "#!/bin/bash", "score": 1.0 } ] } ] }, { "bbox": [ 88, 679, 189, 691 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 87, 678, 190, 693 ], "spans": [ { "bbox": [ 87, 678, 190, 693 ], "type": "text", "content": "# This is a comment", "score": 1.0 } ] } ] }, { "bbox": [ 88, 707, 174, 719 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 88, 706, 176, 721 ], "spans": [ { "bbox": [ 88, 706, 176, 721 ], "type": "text", "content": "echo Hello World", "score": 1.0 } ] } ] }, { "bbox": [ 88, 734, 252, 748 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 89, 734, 252, 749 ], "spans": [ { "bbox": [ 89, 734, 252, 749 ], "type": "text", "content": "上述例子包含三行，以下逐行解释。", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 1 }, { "para_blocks": [ { "bbox": [ 86, 79, 505, 109 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 505, 91 ], "spans": [ { "bbox": [ 89, 79, 505, 91 ], "type": "text", "content": "第一行以“#!”开头，说明脚本的解释器的路径位置信息。Linux 系统根据#! 及该字符串后", "score": 1.0 } ] }, { "bbox": [ 89, 95, 336, 107 ], "spans": [ { "bbox": [ 89, 95, 336, 107 ], "type": "text", "content": "面的信息确定使用哪个解释器对该脚本进行解释执行。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 121, 508, 214 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 90, 123, 505, 134 ], "spans": [ { "bbox": [ 90, 123, 505, 134 ], "type": "text", "content": "上述例子中的 /bin/bash 就表明该文件是一个 BASH 程序，需要由 /bin 目录下的 bash 解", "score": 1.0 } ] }, { "bbox": [ 89, 138, 505, 151 ], "spans": [ { "bbox": [ 89, 138, 505, 151 ], "type": "text", "content": "析器来解释执行。BASH 一般是存放在 /bin 目录下，但是在有的发行版中，bash 也有可", "score": 1.0 } ] }, { "bbox": [ 88, 153, 506, 167 ], "spans": [ { "bbox": [ 88, 153, 506, 167 ], "type": "text", "content": "能被存放在 /sbin 、/usr/local/bin 、/usr/bin 、/usr/sbin 或 /usr/local/sbin 这样的目录", "score": 1.0 } ] }, { "bbox": [ 89, 169, 505, 182 ], "spans": [ { "bbox": [ 89, 169, 505, 182 ], "type": "text", "content": "下，所以在“#!”之后要正确写出解释器路径位置；可以使用 locate、find、which 或", "score": 1.0 } ] }, { "bbox": [ 88, 185, 505, 198 ], "spans": [ { "bbox": [ 88, 185, 505, 198 ], "type": "text", "content": "whereis等命令找出确定bash的具体路径位置。也可以查看/etc/shells文件内容，确定", "score": 1.0 } ] }, { "bbox": [ 88, 200, 142, 213 ], "spans": [ { "bbox": [ 88, 200, 142, 213 ], "type": "text", "content": "bash 路径。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 227, 370, 242 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 227, 368, 243 ], "spans": [ { "bbox": [ 89, 227, 368, 243 ], "type": "text", "content": "另外要说明的是，该行要顶行顶格，前面不要有空行和空格。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 254, 502, 285 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 89, 255, 499, 268 ], "spans": [ { "bbox": [ 89, 255, 499, 268 ], "type": "text", "content": "第二行以“#”字符开头，表示其后的内容是注释，不需要解释执行。这些注释语句是在脚", "score": 1.0 } ] }, { "bbox": [ 89, 271, 294, 282 ], "spans": [ { "bbox": [ 89, 271, 294, 282 ], "type": "text", "content": "本中做一些注释或标记，让脚本更具可读性。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 298, 506, 343 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 297, 505, 312 ], "spans": [ { "bbox": [ 89, 297, 505, 312 ], "type": "text", "content": "第三行的echo 语句的功能是把echo 后面的字符串打印到标准输出stdout。由于echo 后", "score": 1.0 } ] }, { "bbox": [ 88, 313, 474, 328 ], "spans": [ { "bbox": [ 88, 313, 474, 328 ], "type": "text", "content": "跟的是 \"Hello World\" 字符串，因此执行 echo 命令的结果是在终端上输出了 \"Hello", "score": 1.0 } ] }, { "bbox": [ 88, 329, 371, 343 ], "spans": [ { "bbox": [ 88, 329, 371, 343 ], "type": "text", "content": "World\"这个字符串。Bash脚本每行一条命令，无需“;”结束。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 357, 155, 371 ], "type": "title", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 356, 154, 371 ], "spans": [ { "bbox": [ 88, 356, 154, 371 ], "type": "text", "content": "命令解释过程", "score": 1.0 } ] } ] }, { "type": "image", "bbox": [ 92, 388, 197, 491 ], "blocks": [ { "bbox": [ 92, 388, 197, 491 ], "lines": [ { "bbox": [ 92, 388, 197, 491 ], "spans": [ { "bbox": [ 92, 388, 197, 491 ], "type": "image", "image_path": "f0a7db17bad874101f01a82179061db465446ebe08a2ff895797836057ad4ded.jpg" } ] } ], "index": 6, "angle": 0, "type": "image_body" } ], "index": 6 }, { "bbox": [ 86, 505, 459, 519 ], "type": "text", 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"angle": 0, "index": 2, "lines": [ { "bbox": [ 86, 124, 129, 140 ], "spans": [ { "bbox": [ 86, 124, 129, 140 ], "type": "text", "content": "set 命令", "score": 1.0 } ] } ] }, { "bbox": [ 86, 153, 258, 166 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 89, 153, 255, 167 ], "spans": [ { "bbox": [ 89, 153, 255, 167 ], "type": "text", "content": "在脚本内使用 set 命令开启调试选项", "score": 1.0 } ] } ] }, { "bbox": [ 86, 169, 283, 181 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 169, 284, 182 ], "spans": [ { "bbox": [ 88, 169, 284, 182 ], "type": "text", "content": "set -x ：显示由shell执行的命令及其参数", "score": 1.0 } ] } ] }, { "bbox": [ 87, 185, 252, 197 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 185, 251, 198 ], "spans": [ { "bbox": [ 88, 185, 251, 198 ], "type": "text", "content": "set -v ：显示由 shell 读入的命令行", "score": 1.0 } ] } ] }, { "bbox": [ 86, 200, 309, 213 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 200, 310, 214 ], "spans": [ { "bbox": [ 88, 200, 310, 214 ], "type": "text", "content": "set -n ：读取命令但不执行他们，用于语法检查", "score": 1.0 } ] } ] }, { "bbox": [ 86, 215, 298, 228 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 89, 216, 298, 229 ], "spans": [ { "bbox": [ 89, 216, 298, 229 ], "type": "text", "content": "在脚本内使用set命令关闭已开启的调试选项", "score": 1.0 } ] } ] }, { "bbox": [ 87, 232, 120, 243 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 232, 120, 245 ], "spans": [ { "bbox": [ 88, 232, 105, 245 ], "type": "text", "content": "set", "score": 1.0 }, { "bbox": [ 105, 232, 120, 243 ], "type": "inline_equation", "content": "+ \\mathsf { x }", "score": 0.79 } ] } ] }, { "bbox": [ 87, 248, 120, 259 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 247, 119, 261 ], "spans": [ { "bbox": [ 88, 247, 105, 261 ], "type": "text", "content": "set", "score": 1.0 }, { "bbox": [ 105, 248, 119, 258 ], "type": "inline_equation", "content": "+ \\nu", "score": 0.79 } ] } ] }, { "bbox": [ 87, 264, 120, 274 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 263, 120, 276 ], "spans": [ { "bbox": [ 88, 263, 105, 276 ], "type": "text", "content": "set", "score": 1.0 }, { "bbox": [ 105, 264, 120, 274 ], "type": "inline_equation", "content": "+ \\mathsf { n }", "score": 0.81 } ] } ] }, { "bbox": [ 87, 278, 167, 290 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 88, 278, 168, 290 ], "spans": [ { "bbox": [ 88, 278, 168, 290 ], "type": "text", "content": "shell脚本的类型", "score": 1.0 } ] } ] }, { "bbox": [ 87, 306, 153, 318 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 89, 306, 154, 320 ], "spans": [ { "bbox": [ 89, 306, 154, 320 ], "type": "text", "content": "非交互式脚本", "score": 1.0 } ] } ] }, { "bbox": [ 87, 321, 327, 333 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 89, 321, 327, 335 ], "spans": [ { "bbox": [ 89, 321, 327, 335 ], "type": "text", "content": "不需要读取用户的输入, 也不用向用户反馈某些信息", "score": 1.0 } ] } ] }, { "bbox": [ 87, 337, 374, 349 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 89, 337, 374, 350 ], "spans": [ { "bbox": [ 89, 337, 374, 350 ], "type": "text", "content": "每次执行都是可预见的, 因为它不读取用户输入, 参数是固定的", "score": 1.0 } ] } ] }, { "bbox": [ 87, 353, 164, 365 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 88, 352, 165, 367 ], "spans": [ { "bbox": [ 88, 352, 165, 367 ], "type": "text", "content": "可以在后台执行", "score": 1.0 } ] } ] }, { "bbox": [ 88, 368, 143, 380 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 367, 144, 381 ], "spans": [ { "bbox": [ 88, 367, 144, 381 ], "type": "text", "content": "交互式脚本", "score": 1.0 } ] } ] }, { "bbox": [ 87, 383, 383, 396 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 89, 383, 384, 398 ], "spans": [ { "bbox": [ 89, 383, 384, 398 ], "type": "text", "content": "脚本可以读取用户的输入, 实时向用户反馈信息（输出某些信息）", "score": 1.0 } ] } ] }, { "bbox": [ 87, 398, 348, 411 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 89, 399, 348, 412 ], "spans": [ { "bbox": [ 89, 399, 348, 412 ], "type": "text", "content": "这样的脚本更灵活, 每次执行时的参数可由用户动态设定", "score": 1.0 } ] } ] }, { "bbox": [ 87, 414, 351, 428 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 88, 414, 352, 429 ], "spans": [ { "bbox": [ 88, 414, 352, 429 ], "type": "text", "content": "用户界面更友好，但不适用于自动化任务（如 cron 任务）", "score": 1.0 } ] } ] }, { "bbox": [ 87, 430, 239, 443 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 89, 430, 240, 444 ], "spans": [ { "bbox": [ 89, 430, 240, 444 ], "type": "text", "content": "掌握一种文本编辑器的使用（Vi）", "score": 1.0 } ] } ] }, { "bbox": [ 87, 445, 216, 459 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 89, 446, 216, 460 ], "spans": [ { "bbox": [ 89, 446, 216, 460 ], "type": "text", "content": "熟悉 Linux 文件系统的布局", "score": 1.0 } ] } ] }, { "bbox": [ 88, 461, 192, 474 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 88, 461, 192, 476 ], "spans": [ { "bbox": [ 88, 461, 192, 476 ], "type": "text", "content": "学习 Shell 的各种功能", "score": 1.0 } ] } ] }, { "bbox": [ 87, 476, 258, 490 ], "type": "text", "angle": 0, "index": 23, "lines": [ { "bbox": [ 89, 476, 258, 491 ], "spans": [ { "bbox": [ 89, 476, 258, 491 ], "type": "text", "content": "重定向、管道、命令替换、命令聚合", "score": 1.0 } ] } ] }, { "bbox": [ 88, 492, 237, 505 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 89, 493, 237, 506 ], "spans": [ { "bbox": [ 89, 493, 237, 506 ], "type": "text", "content": "学习各种管理和监视命令的使用", "score": 1.0 } ] } ] }, { "bbox": [ 87, 507, 299, 521 ], "type": "text", "angle": 0, "index": 25, "lines": [ { "bbox": [ 89, 508, 300, 522 ], "spans": [ { "bbox": [ 89, 508, 300, 522 ], "type": "text", "content": "用户管理、权限管理、进程管理、包管理……", "score": 1.0 } ] } ] }, { "bbox": [ 88, 523, 208, 536 ], "type": "text", "angle": 0, "index": 26, "lines": [ { "bbox": [ 89, 523, 208, 537 ], "spans": [ { "bbox": [ 89, 523, 208, 537 ], "type": "text", "content": "系统监视、网络监视……", "score": 1.0 } ] } ] }, { "bbox": [ 87, 539, 227, 552 ], "type": "text", "angle": 0, "index": 27, "lines": [ { "bbox": [ 88, 538, 227, 554 ], "spans": [ { "bbox": [ 88, 538, 227, 554 ], "type": "text", "content": "学习各种文本文件工具的使用", "score": 1.0 } ] } ] }, { "bbox": [ 87, 555, 234, 568 ], "type": "text", "angle": 0, "index": 28, "lines": [ { "bbox": [ 88, 554, 235, 571 ], "spans": [ { "bbox": [ 88, 554, 235, 571 ], "type": "text", "content": "cat、grep、tr、sed、awk ……", "score": 1.0 } ] } ] }, { "bbox": [ 88, 571, 143, 582 ], "type": "text", "angle": 0, "index": 29, "lines": [ { "bbox": [ 88, 571, 143, 584 ], "spans": [ { "bbox": [ 88, 571, 143, 584 ], "type": "text", "content": "正则表达式", "score": 1.0 } ] } ] }, { "bbox": [ 87, 613, 137, 626 ], "type": "text", "angle": 0, "index": 30, "lines": [ { "bbox": [ 87, 613, 138, 629 ], "spans": [ { "bbox": [ 87, 613, 138, 629 ], "type": "text", "content": "Shell 环境", "score": 1.0 } ] } ] }, { "bbox": [ 87, 656, 189, 669 ], "type": "text", "angle": 0, "index": 31, "lines": [ { "bbox": [ 89, 657, 189, 670 ], "spans": [ { "bbox": [ 89, 657, 189, 670 ], "type": "text", "content": "运行脚本有多种方法：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 684, 179, 698 ], "type": "text", "angle": 0, "index": 32, "lines": [ { "bbox": [ 87, 684, 180, 698 ], "spans": [ { "bbox": [ 87, 684, 180, 698 ], "type": "text", "content": "# 使用 shell 来执行", "score": 1.0 } ] } ] }, { "bbox": [ 88, 712, 143, 724 ], "type": "text", "angle": 0, "index": 33, "lines": [ { "bbox": [ 88, 710, 145, 726 ], "spans": [ { "bbox": [ 88, 710, 145, 726 ], "type": "text", "content": "sh hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 87, 739, 180, 752 ], "type": "text", "angle": 0, "index": 34, "lines": [ { "bbox": [ 88, 739, 181, 754 ], "spans": [ { "bbox": [ 88, 739, 181, 754 ], "type": "text", "content": "# 使用 bash 来执行", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 4 }, { "para_blocks": [ { "bbox": [ 86, 79, 157, 90 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 88, 78, 157, 92 ], "spans": [ { "bbox": [ 88, 78, 157, 92 ], "type": "text", "content": "bash hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 86, 106, 362, 119 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 107, 362, 121 ], "spans": [ { "bbox": [ 88, 107, 362, 121 ], "type": "text", "content": "# 还可以赋予脚本所有者执行权限，允许该用户执行该脚本", "score": 1.0 } ] } ] }, { "bbox": [ 86, 134, 190, 146 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 133, 191, 148 ], "spans": [ { "bbox": [ 89, 133, 124, 148 ], "type": "text", "content": "chmod", "score": 1.0 }, { "bbox": [ 125, 135, 150, 146 ], "type": "inline_equation", "content": "\\uplus \\dag \\boldsymbol { \\mathsf { r } } \\boldsymbol { \\mathsf { X } }", "score": 0.59 }, { "bbox": [ 150, 133, 191, 148 ], "type": "text", "content": "hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 87, 162, 135, 173 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 161, 136, 175 ], "spans": [ { "bbox": [ 88, 161, 136, 175 ], "type": "text", "content": "./hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 86, 189, 249, 201 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 189, 249, 203 ], "spans": [ { "bbox": [ 88, 189, 249, 203 ], "type": "text", "content": "# 使用.命令来执行，不创建子进程", "score": 1.0 } ] } ] }, { "bbox": [ 87, 216, 141, 228 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 216, 142, 231 ], "spans": [ { "bbox": [ 88, 216, 142, 231 ], "type": "text", "content": ". ./hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 86, 244, 255, 257 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 244, 255, 259 ], "spans": [ { "bbox": [ 88, 244, 255, 259 ], "type": "text", "content": "# 使用 source 来执行，与.命令等价", "score": 1.0 } ] } ] }, { "bbox": [ 86, 272, 164, 283 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 86, 271, 166, 285 ], "spans": [ { "bbox": [ 86, 271, 166, 285 ], "type": "text", "content": "source hello.sh", "score": 1.0 } ] } ] }, { "bbox": [ 87, 300, 242, 312 ], "type": "title", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 299, 242, 314 ], "spans": [ { "bbox": [ 88, 299, 242, 314 ], "type": "text", "content": "1. ./hello.sh 报错 zsh: 权限不够", "score": 1.0 } ] } ] }, { "bbox": [ 86, 327, 498, 340 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 89, 327, 499, 341 ], "spans": [ { "bbox": [ 89, 327, 499, 341 ], "type": "text", "content": "当你直接运行 ./hello.sh 时，系统会尝试把 hello.sh 当作一个可执行程序运行，但要求：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 354, 424, 395 ], "type": "list", "angle": 0, "index": 12, "blocks": [ { "bbox": [ 104, 354, 297, 367 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 108, 352, 300, 371 ], "spans": [ { "bbox": [ 108, 352, 249, 371 ], "type": "text", "content": " 文件必须具有可执行权限（", "score": 1.0 }, { "bbox": [ 249, 355, 259, 367 ], "type": "inline_equation", "content": "\\mathbf { x }", "score": 0.54 }, { "bbox": [ 260, 352, 300, 371 ], "type": "text", "content": "权限）。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 382, 424, 395 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 104, 380, 427, 398 ], "spans": [ { "bbox": [ 104, 380, 189, 398 ], "type": "text", "content": " 如果文件没有", "score": 1.0 }, { "bbox": [ 189, 384, 198, 394 ], "type": "inline_equation", "content": "\\pmb { \\times }", "score": 0.75 }, { "bbox": [ 199, 380, 427, 398 ], "type": "text", "content": "权限，就会报 权限不够（Permission denied）。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 123, 410, 168, 421 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 124, 409, 170, 423 ], "spans": [ { "bbox": [ 124, 409, 170, 423 ], "type": "text", "content": "Chomod", "score": 1.0 } ] } ] }, { "bbox": [ 86, 437, 211, 450 ], "type": "title", "angle": 0, "index": 14, "lines": [ { "bbox": [ 88, 437, 212, 452 ], "spans": [ { "bbox": [ 88, 437, 212, 452 ], "type": "text", "content": "2. . ./hello.sh 能正常运行", "score": 1.0 } ] } ] }, { "bbox": [ 86, 465, 502, 493 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 89, 465, 502, 479 ], "spans": [ { "bbox": [ 89, 465, 502, 479 ], "type": "text", "content": "当你使用 . ./hello.sh（或等价的 source ./hello.sh）时，Shell 会直接在当前 Shell 进程", "score": 1.0 } ] }, { "bbox": [ 88, 481, 310, 494 ], "spans": [ { "bbox": [ 88, 481, 310, 494 ], "type": "text", "content": "中执行脚本内容，而不是启动一个新的子 Shell。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 496, 178, 509 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 496, 181, 511 ], "spans": [ { "bbox": [ 88, 496, 181, 511 ], "type": "text", "content": "这种方式的特点是：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 523, 444, 565 ], "type": "list", "angle": 0, "index": 19, "blocks": [ { "bbox": [ 104, 523, 431, 537 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 104, 523, 434, 539 ], "spans": [ { "bbox": [ 104, 523, 434, 539 ], "type": "text", "content": " 不需要文件有可执行权限（因为 Shell 直接读取文件内容并执行）。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 551, 444, 565 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 105, 550, 445, 565 ], "spans": [ { "bbox": [ 105, 550, 445, 565 ], "type": "text", "content": " 脚本中的变量、函数等会影响当前 Shell 环境（而./hello.sh 不会）。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 578, 169, 592 ], "type": "title", "angle": 0, "index": 20, "lines": [ { "bbox": [ 88, 578, 170, 594 ], "spans": [ { "bbox": [ 88, 578, 170, 594 ], "type": "text", "content": "为什么它能工作？", "score": 1.0 } ] } ] }, { "bbox": [ 104, 606, 424, 647 ], "type": "list", "angle": 0, "index": 23, "blocks": [ { "bbox": [ 104, 606, 377, 619 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 105, 604, 379, 621 ], "spans": [ { "bbox": [ 105, 604, 379, 621 ], "type": "text", "content": " .（或source）是 Shell 的内置命令，不依赖文件权限。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 634, 424, 647 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 104, 634, 426, 648 ], "spans": [ { "bbox": [ 104, 634, 346, 648 ], "type": "text", "content": " 它直接读取文件内容并逐行执行，因此即使没有", "score": 1.0 }, { "bbox": [ 346, 635, 356, 646 ], "type": "inline_equation", "content": "\\pmb { \\times }", "score": 0.78 }, { "bbox": [ 356, 634, 426, 648 ], "type": "text", "content": "权限也能运行。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 661, 408, 675 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 88, 660, 408, 677 ], "spans": [ { "bbox": [ 88, 660, 408, 677 ], "type": "text", "content": "如果想要保存脚本的输出 hello world 为一个文本，那么该怎么办呢？", "score": 1.0 } ] } ] }, { "bbox": [ 89, 689, 150, 701 ], "type": "text", "angle": 0, "index": 25, "lines": [ { "bbox": [ 91, 689, 151, 702 ], "spans": [ { "bbox": [ 91, 689, 151, 702 ], "type": "text", "content": "#!/bin/bash", "score": 1.0 } ] } ] }, { "bbox": [ 89, 717, 229, 729 ], "type": "text", "angle": 0, "index": 26, "lines": [ { "bbox": [ 90, 714, 230, 732 ], "spans": [ { "bbox": [ 90, 714, 183, 732 ], "type": "text", "content": "echo \"hello world\"", "score": 1.0 }, { "bbox": [ 183, 719, 192, 727 ], "type": "inline_equation", "content": ">", "score": 0.78 }, { "bbox": [ 193, 714, 230, 732 ], "type": "text", "content": "my.out", "score": 1.0 } ] } ] }, { "bbox": [ 86, 745, 257, 758 ], "type": "text", "angle": 0, "index": 27, "lines": [ { "bbox": [ 88, 743, 258, 760 ], "spans": [ { "bbox": [ 88, 743, 258, 760 ], "type": "text", "content": "用 cat 命令查看 my.out 文件的内容。", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 5 }, { "para_blocks": [ { "bbox": [ 87, 79, 142, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 88, 79, 143, 94 ], "spans": [ { "bbox": [ 88, 79, 143, 94 ], "type": "text", "content": "cat my.out", "score": 1.0 } ] } ] }, { "bbox": [ 88, 105, 154, 120 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 106, 154, 121 ], "spans": [ { "bbox": [ 89, 106, 154, 121 ], "type": "text", "content": "关键区别总结", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 140, 481, 340 ], "blocks": [ { "bbox": [ 86, 140, 481, 340 ], "lines": [ { "bbox": [ 86, 140, 481, 340 ], "spans": [ { "bbox": [ 86, 140, 481, 340 ], "type": "table", "html": "
方式是否需要x权限执行环境典型用途
./hello.sh需要新的子Shell运行独立脚本
../hello.sh不需要当前Shell加载环境变量或函数到当前会话
bashhello.sh不需要新的子Shell直接指定解释器执行脚本
", "image_path": "82e09f7779ae175bc41788ca22d146bba6f34332ff45be35788c0afb983e9401.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "bbox": [ 88, 353, 143, 366 ], "type": "title", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 354, 143, 367 ], "spans": [ { "bbox": [ 88, 354, 143, 367 ], "type": "text", "content": "正则表达式", "score": 1.0 } ] } ] }, { "bbox": [ 86, 380, 500, 394 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 379, 499, 396 ], "spans": [ { "bbox": [ 88, 379, 499, 396 ], "type": "text", "content": "正则表达式是使用某种模式（pattern）去匹配（matching）一类字符串的一个公式。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 395, 499, 410 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 394, 502, 412 ], "spans": [ { "bbox": [ 88, 394, 502, 412 ], "type": "text", "content": "通 常 使 用 正 则 表 达 式 进 行 查 找 、 替 换 等 操 作 。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 411, 499, 425 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 411, 499, 426 ], "spans": [ { "bbox": [ 88, 411, 499, 426 ], "type": "text", "content": "在 适 当 的 情 况 下 使 用 正 则 表 达 式 可 以 极 大 地 提 高 工 作 效 率 。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 427, 474, 440 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 84, 423, 477, 445 ], "spans": [ { "bbox": [ 84, 423, 477, 445 ], "type": "text", "content": "有 两 种 风 格 的 正 则 表 达 式 ：", "score": 1.0 } ] } ] }, { "bbox": [ 88, 442, 505, 455 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 442, 508, 459 ], "spans": [ { "bbox": [ 88, 442, 123, 458 ], "type": "text", "content": "POSIX", "score": 1.0 }, { "bbox": [ 186, 442, 203, 459 ], "type": "text", "content": "风", "score": 1.0 }, { "bbox": [ 228, 442, 246, 458 ], "type": "text", "content": "格", "score": 1.0 }, { "bbox": [ 273, 442, 290, 459 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 317, 442, 334, 459 ], "type": "text", "content": "正", "score": 1.0 }, { "bbox": [ 359, 442, 377, 459 ], "type": "text", "content": "则", "score": 1.0 }, { "bbox": [ 403, 442, 421, 458 ], "type": "text", "content": "表", "score": 1.0 }, { "bbox": [ 445, 442, 465, 459 ], "type": "text", "content": "达", "score": 1.0 }, { "bbox": [ 490, 442, 508, 459 ], "type": "text", "content": "式", "score": 1.0 } ] } ] }, { "bbox": [ 88, 457, 499, 472 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 87, 456, 500, 476 ], "spans": [ { "bbox": [ 87, 456, 500, 476 ], "type": "text", "content": "Perl 风 格 的 正 则 表 达 式 （ Perl-compatible regular expression ）", "score": 1.0 } ] } ] }, { "bbox": [ 88, 473, 505, 488 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 471, 508, 491 ], "spans": [ { "bbox": [ 88, 472, 282, 489 ], "type": "text", "content": "基 本 的 正 则 表 达 式", "score": 1.0 }, { "bbox": [ 308, 471, 508, 491 ], "type": "text", "content": "Basic regular expression (BRE)", "score": 1.0 } ] } ] }, { "bbox": [ 88, 489, 505, 503 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 87, 487, 508, 507 ], "spans": [ { "bbox": [ 87, 491, 116, 507 ], "type": "text", "content": "grep", "score": 1.0 }, { "bbox": [ 191, 488, 208, 506 ], "type": "text", "content": "按", "score": 1.0 }, { "bbox": [ 241, 488, 258, 506 ], "type": "text", "content": "模", "score": 1.0 }, { "bbox": [ 290, 487, 308, 506 ], "type": "text", "content": "式", "score": 1.0 }, { "bbox": [ 342, 488, 358, 506 ], "type": "text", "content": "匹", "score": 1.0 }, { "bbox": [ 391, 488, 408, 505 ], "type": "text", "content": "配", "score": 1.0 }, { "bbox": [ 441, 488, 458, 506 ], "type": "text", "content": "文", "score": 1.0 }, { "bbox": [ 490, 488, 508, 507 ], "type": "text", "content": "本", "score": 1.0 } ] } ] }, { "bbox": [ 88, 504, 505, 518 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 87, 503, 506, 521 ], "spans": [ { "bbox": [ 87, 504, 105, 521 ], "type": "text", "content": "ed", "score": 1.0 }, { "bbox": [ 203, 503, 224, 520 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 244, 504, 263, 520 ], "type": "text", "content": "原", "score": 1.0 }, { "bbox": [ 286, 504, 305, 520 ], "type": "text", "content": "始", "score": 1.0 }, { "bbox": [ 326, 504, 345, 520 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 367, 504, 386, 520 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 408, 504, 426, 520 ], "type": "text", "content": "编", "score": 1.0 }, { "bbox": [ 449, 504, 467, 519 ], "type": "text", "content": "辑", "score": 1.0 }, { "bbox": [ 490, 504, 506, 520 ], "type": "text", "content": "器", "score": 1.0 } ] } ] }, { "bbox": [ 88, 520, 505, 534 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 85, 518, 508, 536 ], "spans": [ { "bbox": [ 85, 520, 110, 534 ], "type": "text", "content": "sed", "score": 1.0 }, { "bbox": [ 260, 518, 276, 536 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 318, 518, 334, 536 ], "type": "text", "content": "流", "score": 1.0 }, { "bbox": [ 376, 518, 391, 536 ], "type": "text", "content": "编", "score": 1.0 }, { "bbox": [ 433, 518, 449, 536 ], "type": "text", "content": "辑", "score": 1.0 }, { "bbox": [ 491, 518, 508, 536 ], "type": "text", "content": "器", "score": 1.0 } ] } ] }, { "bbox": [ 88, 535, 505, 550 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 86, 534, 508, 552 ], "spans": [ { "bbox": [ 86, 535, 110, 552 ], "type": "text", "content": "vim", "score": 1.0 }, { "bbox": [ 238, 534, 255, 552 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 289, 535, 305, 551 ], "type": "text", "content": "屏", "score": 1.0 }, { "bbox": [ 339, 535, 356, 552 ], "type": "text", "content": "幕", "score": 1.0 }, { "bbox": [ 390, 535, 406, 551 ], "type": "text", "content": "编", "score": 1.0 }, { "bbox": [ 440, 535, 456, 551 ], "type": "text", "content": "辑", "score": 1.0 }, { "bbox": [ 491, 535, 508, 552 ], "type": "text", "content": "器", "score": 1.0 } ] } ] }, { "bbox": [ 88, 551, 505, 565 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 88, 550, 508, 568 ], "spans": [ { "bbox": [ 88, 553, 123, 566 ], "type": "text", "content": "emacs", "score": 1.0 }, { "bbox": [ 247, 550, 264, 567 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 296, 550, 312, 568 ], "type": "text", "content": "屏", "score": 1.0 }, { "bbox": [ 345, 550, 361, 567 ], "type": "text", "content": "幕", "score": 1.0 }, { "bbox": [ 393, 550, 409, 567 ], "type": "text", "content": "编", "score": 1.0 }, { "bbox": [ 442, 550, 459, 567 ], "type": "text", "content": "辑", "score": 1.0 }, { "bbox": [ 491, 550, 508, 568 ], "type": "text", "content": "器", "score": 1.0 } ] } ] }, { "bbox": [ 88, 566, 505, 581 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 565, 508, 585 ], "spans": [ { "bbox": [ 88, 565, 270, 582 ], "type": "text", "content": "扩 展 的 正 则 表 达 式", "score": 1.0 }, { "bbox": [ 293, 565, 508, 585 ], "type": "text", "content": "Extended regular expression (ERE)", "score": 1.0 } ] } ] }, { "bbox": [ 88, 582, 505, 597 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 87, 581, 508, 602 ], "spans": [ { "bbox": [ 87, 583, 121, 602 ], "type": "text", "content": "egrep", "score": 1.0 }, { "bbox": [ 195, 581, 213, 600 ], "type": "text", "content": "按", "score": 1.0 }, { "bbox": [ 245, 581, 261, 598 ], "type": "text", "content": "模", "score": 1.0 }, { "bbox": [ 294, 581, 311, 600 ], "type": "text", "content": "式", "score": 1.0 }, { "bbox": [ 344, 582, 359, 599 ], "type": "text", "content": "匹", "score": 1.0 }, { "bbox": [ 393, 582, 409, 598 ], "type": "text", "content": "配", "score": 1.0 }, { "bbox": [ 441, 582, 459, 599 ], "type": "text", "content": "文", "score": 1.0 }, { "bbox": [ 490, 581, 508, 600 ], "type": "text", "content": "本", "score": 1.0 } ] } ] }, { "bbox": [ 88, 597, 505, 613 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 86, 595, 506, 617 ], "spans": [ { "bbox": [ 86, 597, 113, 614 ], "type": "text", "content": "awk", "score": 1.0 }, { "bbox": [ 169, 597, 186, 614 ], "type": "text", "content": "进", "score": 1.0 }, { "bbox": [ 209, 597, 227, 613 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 240, 596, 308, 615 ], "type": "text", "content": "简 单", "score": 1.0 }, { "bbox": [ 329, 595, 471, 617 ], "type": "text", "content": "的 文 本 处", "score": 1.0 }, { "bbox": [ 490, 598, 506, 613 ], "type": "text", "content": "理", "score": 1.0 } ] } ] }, { "bbox": [ 86, 641, 499, 671 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 88, 641, 499, 655 ], "spans": [ { "bbox": [ 88, 641, 499, 655 ], "type": "text", "content": "在 Shell 中有一些具有特殊的意义字符，称为 Shell 元字符（shell metacharacters）。", "score": 1.0 } ] }, { "bbox": [ 88, 657, 499, 671 ], "spans": [ { "bbox": [ 88, 657, 499, 671 ], "type": "text", "content": "若不以特殊方式（使用转义字符）指明，Shell 并不会把它们当做普通文字符使用。", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 686, 595, 760 ], "blocks": [ { "bbox": [ 88, 686, 595, 760 ], "lines": [ { "bbox": [ 88, 686, 595, 760 ], "spans": [ { "bbox": [ 88, 686, 595, 760 ], "type": "table", "html": "
字符含义字符含义
'强引用*、?、!通配符
\"弱引用<、>、>>重定向
\\转义字符-选项标
$变量引用#注释符
;命令分离符空格、换行符命令分
", "image_path": "383bd1d08ac43e5ebf36da8ca2ec4a658f2b26d0f1b3538235c29a7547a9479d.jpg" } ] } ], "index": 20, "angle": 0, "type": "table_body" } ], "index": 20 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 6 }, { "para_blocks": [ { "type": "table", "bbox": [ 88, 76, 595, 221 ], "blocks": [ { "bbox": [ 88, 76, 595, 221 ], "lines": [], "index": 0, "angle": 0, "type": "table_body", "lines_deleted": true } ], "index": 0 }, { "type": "table", "bbox": [ 88, 248, 595, 745 ], "blocks": [ { "bbox": [ 88, 233, 167, 247 ], "lines": [ { "bbox": [ 88, 233, 168, 248 ], "spans": [ { "bbox": [ 88, 233, 168, 248 ], "type": "text", "content": "通配符（元字符）", "score": 1.0 } ] } ], "index": 1, "angle": 0, "type": "table_caption" }, { "bbox": [ 88, 248, 595, 745 ], "lines": [ { "bbox": [ 88, 248, 595, 745 ], "spans": [ { "bbox": [ 88, 248, 595, 745 ], "type": "table", "html": "
元字符含义类型举例说明
^匹配首字符BRE^x以字符x开
$匹配尾字符BREx$以x字符结
.匹配任意一个字符BREl..elove, life, l
?匹配任意一个可选字符ERExy?x, xy
*匹配零次或多次重复BRExy*x, xy, xyy, x
+匹配一次或多次重复ERExy+xy, xyy, xyy
[...]匹配任意一个字符BRE[xyz]x, y, z
()对正则表达式分组ERE(xy)+xy, xyxy, x
元字符含义类型举例说明
\\{n\\}匹配n次BREgo{\\2}\\glegoogle
\\{n,\\}匹配最少n次BREgo{\\2,\\}glegoogle, google, goooo
\\{n,m\\}匹配n到m次BREgo{\\2,4}\\glegoogle, google, goooo
{n}匹配n次EREgo{2}glegoogle
{n,}匹配最少n次EREgo{2,}glegoogle, google, goooo
{n,m}匹配n到m次EREgo{2,4}glegoogle, google, goooo
|以或逻辑连接多个匹配EREgood|bon匹配 good 或 bon
\\转义字符BRE\\**
元字符含义类型举例说明
^非（仅用于启始字符）BRE^[^xyz]匹配xy
-用于指明字符范围(不能是首字符和尾字符)BRE[a-zA-Z]匹配任
\\转义字符BRE[\\.]\\.
", "image_path": "40e96966f78386d62aa3bfc0502b229d2c9039a9cb83b951152d92d318aed4f4.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 7 }, { "para_blocks": [ { "type": "table", "bbox": [ 85, 73, 595, 491 ], "blocks": [ { "bbox": [ 85, 73, 595, 491 ], "lines": [], "index": 0, "angle": 0, "type": "table_body", "lines_deleted": true } ], "index": 0 }, { "bbox": [ 88, 528, 506, 544 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 164, 528, 507, 545 ], "spans": [ { "bbox": [ 164, 528, 182, 545 ], "type": "text", "content": "任", "score": 1.0 }, { "bbox": [ 211, 528, 227, 545 ], "type": "text", "content": "意", "score": 1.0 }, { "bbox": [ 305, 528, 321, 545 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 351, 528, 368, 545 ], "type": "text", "content": "普", "score": 1.0 }, { "bbox": [ 398, 528, 414, 544 ], "type": "text", "content": "通", "score": 1.0 }, { "bbox": [ 445, 528, 461, 545 ], "type": "text", "content": "字", "score": 1.0 }, { "bbox": [ 491, 528, 507, 545 ], "type": "text", "content": "符", "score": 1.0 } ] } ] }, { "bbox": [ 86, 571, 506, 585 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 570, 507, 587 ], "spans": [ { "bbox": [ 89, 575, 96, 581 ], "type": "text", "content": "大", "score": 0.975 }, { "bbox": [ 103, 570, 507, 587 ], "type": "text", "content": "： 匹 配 任 何 字 符 和 任 何 数 目 的 字 符", "score": 1.0 } ] } ] }, { "bbox": [ 88, 587, 505, 602 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 585, 508, 605 ], "spans": [ { "bbox": [ 88, 590, 96, 601 ], "type": "text", "content": "?", "score": 1.0 }, { "bbox": [ 116, 592, 124, 597 ], "type": "text", "content": "·", "score": 0.709 }, { "bbox": [ 148, 585, 508, 605 ], "type": "text", "content": "匹 配 单 一 数 目 的 任 何 字 符", "score": 1.0 } ] } ] }, { "bbox": [ 88, 603, 505, 617 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 600, 508, 621 ], "spans": [ { "bbox": [ 89, 605, 96, 614 ], "type": "text", "content": ">", "score": 0.691 }, { "bbox": [ 241, 602, 257, 620 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 325, 602, 341, 619 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 408, 602, 424, 620 ], "type": "text", "content": "开", "score": 1.0 }, { "bbox": [ 490, 600, 508, 621 ], "type": "text", "content": "始", "score": 1.0 } ] } ] }, { "bbox": [ 88, 619, 505, 632 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 618, 508, 635 ], "spans": [ { "bbox": [ 88, 620, 97, 632 ], "type": "inline_equation", "content": "\\$ 1", "score": 0.51 }, { "bbox": [ 241, 618, 257, 635 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 325, 618, 340, 635 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 408, 618, 424, 635 ], "type": "text", "content": "结", "score": 1.0 }, { "bbox": [ 491, 618, 508, 635 ], "type": "text", "content": "束", "score": 1.0 } ] } ] }, { "bbox": [ 88, 634, 505, 648 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 85, 630, 509, 654 ], "spans": [ { "bbox": [ 85, 633, 108, 654 ], "type": "text", "content": "[…]", "score": 1.0 }, { "bbox": [ 143, 630, 509, 653 ], "type": "text", "content": "在 […] 列 表 中 的 任 意 一 个 字 符", "score": 1.0 } ] } ] }, { "bbox": [ 88, 650, 220, 664 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 650, 219, 665 ], "spans": [ { "bbox": [ 88, 650, 219, 665 ], "type": "text", "content": "[^…] 不在列表中的任一字符", "score": 1.0 } ] } ] }, { "bbox": [ 86, 677, 505, 691 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 86, 677, 506, 692 ], "spans": [ { "bbox": [ 86, 677, 506, 692 ], "type": "text", "content": "[! ] ： 匹 配 除 了 [! ] 之 外 的 任 意 一 个 字 符 ， ! 表 示 非 的 意 思", "score": 1.0 } ] } ] }, { "bbox": [ 88, 693, 499, 707 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 86, 692, 477, 709 ], "spans": [ { "bbox": [ 86, 693, 108, 704 ], "type": "text", "content": "=*\"", "score": 0.773 }, { "bbox": [ 116, 692, 424, 709 ], "type": "text", "content": "能 匹 配 文 件 或 目 录 名 中 的", "score": 1.0 }, { "bbox": [ 445, 694, 451, 699 ], "type": "text", "content": "66", "score": 0.78 }, { "bbox": [ 470, 695, 477, 700 ], "type": "text", "content": "", "score": 0.0 } ] }, { "bbox": [ 493, 700, 499, 707 ], "spans": [ { "bbox": [ 493, 700, 499, 707 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 709, 277, 723 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 708, 277, 724 ], "spans": [ { "bbox": [ 88, 708, 277, 724 ], "type": "text", "content": "“*”不能匹配首字符是“.”的文件或目录名", "score": 1.0 } ] } ] }, { "bbox": [ 87, 736, 506, 751 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 88, 735, 507, 753 ], "spans": [ { "bbox": [ 88, 736, 98, 751 ], "type": "text", "content": "$", "score": 1.0 }, { "bbox": [ 179, 735, 195, 753 ], "type": "text", "content": "代", "score": 1.0 }, { "bbox": [ 232, 736, 246, 751 ], "type": "text", "content": "表", "score": 1.0 }, { "bbox": [ 283, 735, 299, 753 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 336, 736, 350, 751 ], "type": "text", "content": "量", "score": 1.0 }, { "bbox": [ 387, 736, 402, 751 ], "type": "text", "content": "值", "score": 1.0 }, { "bbox": [ 440, 736, 455, 751 ], "type": "text", "content": "置", "score": 1.0 }, { "bbox": [ 491, 735, 507, 753 ], "type": "text", "content": "换", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 8 }, { "para_blocks": [ { "type": "table", "bbox": [ 88, 79, 508, 154 ], "blocks": [ { "bbox": [ 88, 79, 508, 154 ], "lines": [ { "bbox": [ 88, 79, 508, 154 ], "spans": [ { "bbox": [ 88, 79, 508, 154 ], "type": "table", "html": "
$$PATH
$echo${mname}
$nname=bigdata
$echo${mname}
", "image_path": "36dec5bbc95b0522a68a5bf7b0eb755a094482f37b3a2e7896e71cd713aa157c.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "type": "table", "bbox": [ 87, 199, 508, 306 ], "blocks": [ { "bbox": [ 87, 199, 508, 306 ], "lines": [ { "bbox": [ 87, 199, 508, 306 ], "spans": [ { "bbox": [ 87, 199, 508, 306 ], "type": "table", "html": "
特 点(characteristic)
解释性
速度慢
组合、灵活
Tab键与历史命令
脚本与函数
子程序
", "image_path": "643501a2a06a7a8c19638356621268029c10bf1b74322a6c3f0c352ab0412a2f.jpg" } ] } ], "index": 1, "angle": 0, "type": "table_body" } ], "index": 1 }, { "bbox": [ 88, 309, 164, 322 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 88, 308, 165, 324 ], "spans": [ { "bbox": [ 88, 308, 165, 324 ], "type": "text", "content": "命令行执行过程", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 335, 502, 396 ], "blocks": [ { "bbox": [ 88, 335, 502, 396 ], "lines": [ { "bbox": [ 88, 335, 502, 396 ], "spans": [ { "bbox": [ 88, 335, 502, 396 ], "type": "table", "html": "
将命令行分成单个命令词
展开别名
展开大括号中的声明({}
展开颚化声明(~
", "image_path": "465055c63139246978be5884b66640de9159f6756cc2a48fa72277d0bb236f1d.jpg" } ] } ], "index": 3, "angle": 0, "type": "table_body" } ], "index": 3 }, { "type": "table", "bbox": [ 88, 398, 502, 506 ], "blocks": [ { "bbox": [ 88, 398, 502, 506 ], "lines": [ { "bbox": [ 88, 398, 502, 506 ], "spans": [ { "bbox": [ 88, 398, 502, 506 ], "type": "table", "html": "
命 令 替 换 ($() 或 “”)
再 次 把 命 令 行 分 成 命 令 词
展 开 文 件 通 配 (*、?、[abc] 等 等)
准 备 I/0 重 定 向 (<、>
运 行 命 令 !
显 示 当 前 Shell 可 见 的 全 局 变 量
export[-p]
", "image_path": "3afa85af89b14c5bcb855c970df53fa1b4a54d272e221ac130d283a470c7b06b.jpg" } ] } ], "index": 4, "angle": 0, "type": "table_body" } ], "index": 4 }, { "type": "table", "bbox": [ 88, 507, 505, 600 ], "blocks": [ { "bbox": [ 88, 507, 505, 600 ], "lines": [ { "bbox": [ 88, 507, 505, 600 ], "spans": [ { "bbox": [ 88, 507, 505, 600 ], "type": "table", "html": "
定义 变量 值的 同时 声明 为 全局 变量 export < 变量 名 1= 值 1> [< 变量 名 2= 值 2> ...] 声 明 已 经 赋 值 的 某 个 ( 些 ) 局 部 变 量 为 全 局 变 量 export < 变量 名 1> [< 变量 名 2> ...] 声 明 已 经 赋 值 的 某 个 ( 些 ) 全 局 变 量 为 局 部 变 量 export -n < 变量 名 1> [< 变量 名 2> ...]
", "image_path": "8a9ecb025b8f69306c1a18543d3a67b54e28f15084b19f54238422e225013184.jpg" } ] } ], "index": 5, "angle": 0, "type": "table_body" } ], "index": 5 }, { "bbox": [ 88, 635, 154, 654 ], "type": "title", "angle": 0, "index": 6, "lines": [ { "bbox": [ 86, 634, 157, 656 ], "spans": [ { "bbox": [ 86, 634, 157, 656 ], "type": "text", "content": "变量概念", "score": 1.0 } ] } ] }, { "bbox": [ 86, 691, 509, 751 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 89, 692, 510, 703 ], "spans": [ { "bbox": [ 89, 692, 510, 703 ], "type": "text", "content": "Shell 变量就是计算机中用于记录一个值（不一定是数值，也可以是字符或字符串）的符号，", "score": 1.0 } ] }, { "bbox": [ 89, 707, 506, 719 ], "spans": [ { "bbox": [ 89, 707, 506, 719 ], "type": "text", "content": "而这些符号将用于不同的运算处理中。通常变量与值是一对一的关系，可以通过表达式读", "score": 1.0 } ] }, { "bbox": [ 89, 723, 506, 735 ], "spans": [ { "bbox": [ 89, 723, 506, 735 ], "type": "text", "content": "取它的值并赋值给其它变量，也可以直接指定数值赋值给任意变量。为了便于运算和处理", "score": 1.0 } ] }, { "bbox": [ 90, 739, 505, 751 ], "spans": [ { "bbox": [ 90, 739, 505, 751 ], "type": "text", "content": "大部分的编程语言会区分变量的类型，用于分别记录数值、字符或者字符串等等数据类型", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 9 }, { "para_blocks": [ { "bbox": [ 86, 79, 506, 109 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 505, 92 ], "spans": [ { "bbox": [ 89, 79, 505, 92 ], "type": "text", "content": "Shell 中的变量也基本如此，有不同类型（但不用专门指定类型名），可以参与运算，有作", "score": 1.0 } ] }, { "bbox": [ 88, 94, 138, 109 ], "spans": [ { "bbox": [ 88, 94, 138, 109 ], "type": "text", "content": "用域限定。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 121, 508, 152 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 122, 505, 135 ], "spans": [ { "bbox": [ 89, 122, 505, 135 ], "type": "text", "content": "变量的作用域即变量的有效范围（比如一个函数中、一个源文件中或者全局范围），在该", "score": 1.0 } ] }, { "bbox": [ 89, 138, 462, 151 ], "spans": [ { "bbox": [ 89, 138, 462, 151 ], "type": "text", "content": "范围内只能有一个同名变量。一旦离开则该变量无效，如同不存在这个变量一般。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 164, 508, 257 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 87, 163, 508, 180 ], "spans": [ { "bbox": [ 87, 164, 117, 179 ], "type": "text", "content": "Shell", "score": 1.0 }, { "bbox": [ 163, 163, 508, 180 ], "type": "text", "content": "变 量 大 致 可 以 分 为 三 类", "score": 1.0 } ] }, { "bbox": [ 88, 179, 502, 195 ], "spans": [ { "bbox": [ 88, 179, 502, 195 ], "type": "text", "content": "内 部 变 量 ： 由 系 统 提 供 ， 用 户 只 能 使 用 不 能 修 改 。", "score": 1.0 } ] }, { "bbox": [ 88, 195, 500, 210 ], "spans": [ { "bbox": [ 88, 195, 500, 210 ], "type": "text", "content": "用 户 变 量 ： 由 用 户 建 立 和 修 改 ， 在 shell 脚 本 编 写 中 会 经 常 用 到 。", "score": 1.0 } ] }, { "bbox": [ 88, 211, 506, 225 ], "spans": [ { "bbox": [ 88, 211, 506, 225 ], "type": "text", "content": "环境变量：这些变量决定了用户工作的环境，它们不需要用户去定义，可以直接在 shell", "score": 1.0 } ] }, { "bbox": [ 88, 227, 502, 243 ], "spans": [ { "bbox": [ 88, 227, 502, 243 ], "type": "text", "content": "中 使 用 ， 其 中 某 些 变 量 用 户 可 以 修 改 。", "score": 1.0 } ] }, { "bbox": [ 88, 243, 145, 257 ], "spans": [ { "bbox": [ 88, 243, 145, 257 ], "type": "text", "content": "变量的操作", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 269, 508, 568 ], "blocks": [ { "bbox": [ 86, 269, 508, 568 ], "lines": [ { "bbox": [ 86, 269, 508, 568 ], "spans": [ { "bbox": [ 86, 269, 508, 568 ], "type": "table", "html": "
变量替换扩展
变量测试
变量的字符串操作
变量的间接引用
变量的数值计算
$[expression]
$(expression))
expr
let
declare-i
输入
变量赋值
name=value
readonly
从标准输入读取
read
输出
echo
printf
", "image_path": "0536e695b11d309596acdebad749bd94578fb63b88be318d3fd77cf65e71f787.jpg" } ] } ], "index": 3, "angle": 0, "type": "table_body" } ], "index": 3 }, { "type": "table", "bbox": [ 86, 634, 595, 753 ], "blocks": [ { "bbox": [ 88, 594, 154, 608 ], "lines": [ { "bbox": [ 89, 595, 154, 608 ], "spans": [ { "bbox": [ 89, 595, 154, 608 ], "type": "text", "content": "变量替换扩展", "score": 1.0 } ] } ], "index": 4, "angle": 0, "type": "table_caption" }, { "bbox": [ 86, 634, 595, 753 ], "lines": [ { "bbox": [ 86, 634, 595, 753 ], "spans": [ { "bbox": [ 86, 634, 595, 753 ], "type": "table", "html": "
Use Default Values${var:-word}若 var 存在且非空,则值为$var; 若 word, 但 var 的值不变。
Assign Default Values${var:=word}若 var 存在且非空,则值为$var; 若 word, 且 var 被赋值 word。
Display Error if Null or Unset${var:?word}若 var 存在且非空,则值为 $var; 若 v 息 word,并终止脚本。
Use Alternate Value${var:+word}若 var 存在且非空,则值为 word; 若变。
", "image_path": "a730f7dfebc838bf3d7e8189fdabbb7e839d05e7a4f5e656a3517289ea8818ef.jpg" } ] } ], "index": 5, "angle": 0, "type": "table_body" } ], "index": 5 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 10 }, { "para_blocks": [ { "type": "table", "bbox": [ 86, 76, 595, 243 ], "blocks": [ { "bbox": [ 86, 76, 595, 243 ], "lines": [], "index": 0, "angle": 0, "type": "table_body", "lines_deleted": true } ], "index": 0 }, { "type": "table", "bbox": [ 87, 323, 595, 581 ], "blocks": [ { "bbox": [ 88, 311, 175, 323 ], "lines": [ { "bbox": [ 89, 311, 174, 324 ], "spans": [ { "bbox": [ 89, 311, 174, 324 ], "type": "text", "content": "字符串计数、截取", "score": 1.0 } ] } ], "index": 1, "angle": 0, "type": "table_caption" }, { "bbox": [ 87, 323, 595, 581 ], "lines": [ { "bbox": [ 87, 323, 595, 581 ], "spans": [ { "bbox": [ 87, 323, 595, 581 ], "type": "table", "html": "
${var}返回字符串变量 var 的长度
${var:m}返回${var}中从第 m 个字符到最后的部分
${var:m:len}返回${var}中从第 m 个字符开始，长度为 len 的部分
${var#pattern}删除${var}中开头部分与 pattern 匹配的最小部分
${var##pattern}删除${var}中开头部分与 pattern 匹配的最大部分
${var%pattern}删除${var}中结尾部分与 pattern 匹配的最小部分
${var%%pattern}删除${var}中结尾部分与 pattern 匹配的最大部分
", "image_path": "5858d712a5426a6e573b0c3b8300685b6ab9b9aeb0c03e5249ae5415888f8217.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "type": "table", "bbox": [ 87, 605, 595, 751 ], "blocks": [ { "bbox": [ 88, 592, 143, 605 ], "lines": [ { "bbox": [ 89, 592, 143, 606 ], "spans": [ { "bbox": [ 89, 592, 143, 606 ], "type": "text", "content": "字符串替换", "score": 1.0 } ] } ], "index": 3, "angle": 0, "type": "table_caption" }, { "bbox": [ 87, 605, 595, 751 ], "lines": [ { "bbox": [ 87, 605, 595, 751 ], "spans": [ { "bbox": [ 87, 605, 595, 751 ], "type": "table", "html": "
${var/old/new}用 new 替换${var}中第一次出现的 old
${var//old/new}用 new 替换${var}中所有的 old(全局替换)
${var/#old/new}用 new 替换${var}中开头部分与 old 匹配的部分
${var/%old/new}用 new 替换${var}中结尾部分与 old 匹配的部分
", "image_path": "4514340594c97bd1abcae8d31ce6b1b7ea421e8f5cebc389574a6130a3a5bccd.jpg" } ] } ], "index": 4, "angle": 0, "type": "table_body" } ], "index": 4 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 11 }, { "para_blocks": [ { "bbox": [ 140, 78, 500, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 141, 75, 499, 96 ], "spans": [ { "bbox": [ 141, 77, 163, 94 ], "type": "text", "content": "old", "score": 1.0 }, { "bbox": [ 202, 75, 352, 96 ], "type": "text", "content": "中 可 以 使 用", "score": 1.0 }, { "bbox": [ 390, 76, 499, 95 ], "type": "text", "content": "通 配 符 。", "score": 1.0 } ] } ] }, { "bbox": [ 140, 94, 505, 123 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 148, 94, 506, 109 ], "spans": [ { "bbox": [ 148, 94, 255, 109 ], "type": "text", "content": "（ 2 ） var 可 以 是", "score": 1.0 }, { "bbox": [ 255, 95, 268, 108 ], "type": "inline_equation", "content": "@", "score": 0.72 }, { "bbox": [ 268, 94, 506, 109 ], "type": "text", "content": "或 * ， 表 示 对 每 个 位 置 参 数 进 行 替 换", "score": 1.0 } ] }, { "bbox": [ 141, 110, 167, 124 ], "spans": [ { "bbox": [ 141, 110, 167, 124 ], "type": "text", "content": "eval", "score": 1.0 } ] } ] }, { "bbox": [ 86, 136, 508, 151 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 85, 134, 508, 156 ], "spans": [ { "bbox": [ 85, 136, 113, 152 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 182, 135, 211, 156 ], "type": "text", "content": "arg1", "score": 1.0 }, { "bbox": [ 280, 135, 317, 155 ], "type": "text", "content": "[arg2]", "score": 1.0 }, { "bbox": [ 390, 145, 395, 148 ], "type": "text", "content": "..", "score": 1.0 }, { "bbox": [ 470, 134, 508, 154 ], "type": "text", "content": "[argN]", "score": 1.0 } ] } ] }, { "bbox": [ 88, 153, 506, 167 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 152, 506, 169 ], "spans": [ { "bbox": [ 88, 152, 149, 169 ], "type": "text", "content": "listpage=\"ls", "score": 1.0 }, { "bbox": [ 249, 153, 261, 168 ], "type": "text", "content": "-l", "score": 1.0 }, { "bbox": [ 361, 155, 370, 166 ], "type": "text", "content": "|", "score": 1.0 }, { "bbox": [ 471, 153, 506, 168 ], "type": "text", "content": "more\"", "score": 1.0 } ] } ] }, { "bbox": [ 88, 169, 506, 182 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 86, 167, 508, 186 ], "spans": [ { "bbox": [ 86, 168, 112, 183 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 458, 167, 508, 186 ], "type": "text", "content": "$listpage", "score": 1.0 } ] } ] }, { "bbox": [ 86, 211, 507, 224 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 86, 211, 506, 225 ], "spans": [ { "bbox": [ 86, 211, 112, 225 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 428, 212, 506, 225 ], "type": "text", "content": "newstr=\\$$str2", "score": 1.0 } ] } ] }, { "bbox": [ 88, 227, 506, 240 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 87, 224, 507, 243 ], "spans": [ { "bbox": [ 87, 226, 113, 242 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 265, 224, 295, 242 ], "type": "text", "content": "echo", "score": 1.0 }, { "bbox": [ 448, 225, 507, 243 ], "type": "text", "content": "\\$${x}_URL", "score": 1.0 } ] } ] }, { "bbox": [ 86, 269, 506, 283 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 85, 267, 509, 288 ], "spans": [ { "bbox": [ 85, 267, 509, 288 ], "type": "text", "content": "对 参 数 进 行 两 次 扫 描 和 替 换", "score": 1.0 } ] } ] }, { "bbox": [ 101, 285, 506, 299 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 102, 285, 506, 300 ], "spans": [ { "bbox": [ 102, 285, 506, 300 ], "type": "text", "content": "将 所 有 的 参 数 连 接 成 一 个 表 达 式 ， 并 计 算 或 执 行 该 表 达 式", "score": 1.0 } ] } ] }, { "bbox": [ 129, 301, 506, 314 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 127, 299, 508, 317 ], "spans": [ { "bbox": [ 127, 299, 508, 317 ], "type": "text", "content": "参 数 中 的 任 何 变 量 都 将 被 展 开", "score": 1.0 } ] } ] }, { "bbox": [ 88, 317, 164, 330 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 89, 317, 164, 331 ], "spans": [ { "bbox": [ 89, 317, 164, 331 ], "type": "text", "content": "变量的间接引用", "score": 1.0 } ] } ] }, { "bbox": [ 87, 344, 232, 358 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 344, 232, 358 ], "spans": [ { "bbox": [ 89, 344, 232, 358 ], "type": "text", "content": "通过str2的值来引用str1的值", "score": 1.0 } ] } ] }, { "bbox": [ 86, 371, 508, 386 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 86, 371, 506, 386 ], "spans": [ { "bbox": [ 86, 372, 146, 386 ], "type": "text", "content": "str1=\"Hello", "score": 1.0 }, { "bbox": [ 468, 371, 506, 386 ], "type": "text", "content": "World\"", "score": 1.0 } ] } ] }, { "bbox": [ 88, 388, 506, 400 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 88, 388, 135, 402 ], "spans": [ { "bbox": [ 88, 388, 107, 402 ], "type": "text", "content": "str2", "score": 1.0 }, { "bbox": [ 108, 390, 115, 399 ], "type": "inline_equation", "content": "\\cdot ^ { = }", "score": 0.59 }, { "bbox": [ 116, 388, 135, 402 ], "type": "text", "content": "str1", "score": 1.0 } ] } ] }, { "bbox": [ 88, 404, 506, 416 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 87, 401, 508, 419 ], "spans": [ { "bbox": [ 87, 401, 116, 419 ], "type": "text", "content": "echo", "score": 1.0 }, { "bbox": [ 476, 402, 508, 419 ], "type": "text", "content": "$str2", "score": 1.0 } ] } ] }, { "bbox": [ 88, 419, 506, 431 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 86, 419, 506, 433 ], "spans": [ { "bbox": [ 86, 419, 112, 433 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 427, 419, 506, 433 ], "type": "text", "content": "newstr=\\$$str2", "score": 1.0 } ] } ] }, { "bbox": [ 88, 435, 506, 447 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 433, 506, 449 ], "spans": [ { "bbox": [ 88, 433, 116, 449 ], "type": "text", "content": "echo", "score": 1.0 }, { "bbox": [ 463, 433, 506, 449 ], "type": "text", "content": "$newstr", "score": 1.0 } ] } ] }, { "bbox": [ 88, 451, 506, 462 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 87, 449, 507, 465 ], "spans": [ { "bbox": [ 87, 449, 117, 465 ], "type": "text", "content": "Hello", "score": 1.0 }, { "bbox": [ 473, 449, 507, 465 ], "type": "text", "content": "World", "score": 1.0 } ] } ] }, { "bbox": [ 88, 466, 101, 478 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 88, 465, 103, 481 ], "spans": [ { "bbox": [ 88, 465, 103, 481 ], "type": "text", "content": "或", "score": 1.0 } ] } ] }, { "bbox": [ 88, 481, 506, 493 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 85, 479, 508, 497 ], "spans": [ { "bbox": [ 85, 480, 112, 496 ], "type": "text", "content": "eval", "score": 1.0 }, { "bbox": [ 275, 480, 304, 497 ], "type": "text", "content": "echo", "score": 1.0 }, { "bbox": [ 467, 479, 508, 497 ], "type": "text", "content": "\\$$str2", "score": 1.0 } ] } ] }, { "bbox": [ 88, 497, 506, 509 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 87, 496, 507, 512 ], "spans": [ { "bbox": [ 87, 496, 117, 512 ], "type": "text", "content": "Hello", "score": 1.0 }, { "bbox": [ 473, 496, 507, 512 ], "type": "text", "content": "World", "score": 1.0 } ] } ] }, { "bbox": [ 88, 513, 506, 525 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 88, 511, 508, 529 ], "spans": [ { "bbox": [ 88, 512, 101, 527 ], "type": "text", "content": "＃", "score": 1.0 }, { "bbox": [ 189, 512, 232, 528 ], "type": "text", "content": "bash2.0", "score": 1.0 }, { "bbox": [ 274, 512, 289, 529 ], "type": "text", "content": "以", "score": 1.0 }, { "bbox": [ 327, 511, 344, 529 ], "type": "text", "content": "上", "score": 1.0 }, { "bbox": [ 381, 511, 398, 528 ], "type": "text", "content": "才", "score": 1.0 }, { "bbox": [ 436, 511, 453, 529 ], "type": "text", "content": "支", "score": 1.0 }, { "bbox": [ 490, 511, 508, 529 ], "type": "text", "content": "持", "score": 1.0 } ] } ] }, { "bbox": [ 88, 528, 506, 541 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 87, 526, 167, 544 ], "spans": [ { "bbox": [ 87, 526, 167, 544 ], "type": "text", "content": "newstr=${!str2}", "score": 1.0 } ] } ] }, { "bbox": [ 88, 544, 506, 556 ], "type": "text", "angle": 0, "index": 23, "lines": [ { "bbox": [ 88, 543, 506, 559 ], "spans": [ { "bbox": [ 88, 543, 116, 559 ], "type": "text", "content": "echo", "score": 1.0 }, { "bbox": [ 463, 543, 506, 558 ], "type": "text", "content": "$newstr", "score": 1.0 } ] } ] }, { "bbox": [ 88, 560, 506, 571 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 87, 558, 507, 574 ], "spans": [ { "bbox": [ 87, 558, 117, 574 ], "type": "text", "content": "Hello", "score": 1.0 }, { "bbox": [ 473, 558, 507, 574 ], "type": "text", "content": "World", "score": 1.0 } ] } ] }, { "bbox": [ 88, 576, 101, 587 ], "type": "text", "angle": 0, "index": 25, "lines": [ { "bbox": [ 88, 575, 103, 591 ], "spans": [ { "bbox": [ 88, 575, 103, 591 ], "type": "text", "content": "或", "score": 1.0 } ] } ] }, { "bbox": [ 88, 592, 506, 603 ], "type": "text", "angle": 0, "index": 26, "lines": [ { "bbox": [ 87, 589, 116, 606 ], "spans": [ { "bbox": [ 87, 589, 116, 606 ], "type": "text", "content": "echo", "score": 1.0 } ] } ] }, { "bbox": [ 88, 607, 506, 618 ], "type": "text", "angle": 0, "index": 27, "lines": [ { "bbox": [ 87, 605, 507, 620 ], "spans": [ { "bbox": [ 87, 605, 117, 620 ], "type": "text", "content": "Hello", "score": 1.0 }, { "bbox": [ 473, 605, 507, 620 ], "type": "text", "content": "World", "score": 1.0 } ] } ] }, { "bbox": [ 88, 622, 167, 634 ], "type": "text", "angle": 0, "index": 28, "lines": [ { "bbox": [ 88, 622, 168, 636 ], "spans": [ { "bbox": [ 88, 622, 168, 636 ], "type": "text", "content": "shell变量的分类", "score": 1.0 } ] } ] }, { "bbox": [ 86, 649, 506, 662 ], "type": "text", "angle": 0, "index": 29, "lines": [ { "bbox": [ 86, 647, 507, 667 ], "spans": [ { "bbox": [ 86, 647, 102, 665 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 154, 647, 169, 666 ], "type": "text", "content": "户", "score": 1.0 }, { "bbox": [ 223, 648, 236, 665 ], "type": "text", "content": "自", "score": 1.0 }, { "bbox": [ 288, 647, 306, 666 ], "type": "text", "content": "定", "score": 1.0 }, { "bbox": [ 356, 647, 373, 667 ], "type": "text", "content": "义", "score": 1.0 }, { "bbox": [ 423, 647, 440, 666 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 491, 647, 507, 665 ], "type": "text", "content": "量", "score": 1.0 } ] } ] }, { "bbox": [ 88, 665, 506, 678 ], "type": "text", "angle": 0, "index": 30, "lines": [ { "bbox": [ 85, 660, 509, 685 ], "spans": [ { "bbox": [ 85, 660, 509, 685 ], "type": "text", "content": "由 用 户 自 己 定 义 、 修 改 和 使 用", "score": 1.0 } ] } ] }, { "bbox": [ 88, 681, 506, 693 ], "type": "text", "angle": 0, "index": 31, "lines": [ { "bbox": [ 86, 678, 507, 698 ], "spans": [ { "bbox": [ 86, 679, 116, 696 ], "type": "text", "content": "Shell", "score": 1.0 }, { "bbox": [ 251, 679, 268, 698 ], "type": "text", "content": "环", "score": 1.0 }, { "bbox": [ 331, 678, 348, 698 ], "type": "text", "content": "境", "score": 1.0 }, { "bbox": [ 412, 679, 427, 697 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 492, 679, 507, 696 ], "type": "text", "content": "量", "score": 1.0 } ] } ] }, { "bbox": [ 88, 696, 506, 708 ], "type": "text", "angle": 0, "index": 32, "lines": [ { "bbox": [ 88, 694, 507, 711 ], "spans": [ { "bbox": [ 88, 694, 507, 711 ], "type": "text", "content": "由 系 统 维 护 ， 用 于 设 置 用 户 的 Shell 工 作 环 境", "score": 1.0 } ] } ] }, { "bbox": [ 88, 711, 506, 724 ], "type": "text", "angle": 0, "index": 33, "lines": [ { "bbox": [ 86, 709, 508, 728 ], "spans": [ { "bbox": [ 86, 709, 508, 728 ], "type": "text", "content": "只 有 少 数 的 变 量 用 户 可 以 修 改 其 值", "score": 1.0 } ] } ] }, { "bbox": [ 88, 727, 499, 740 ], "type": "text", "angle": 0, "index": 34, "lines": [ { "bbox": [ 86, 724, 500, 744 ], "spans": [ { "bbox": [ 86, 724, 280, 744 ], "type": "text", "content": "位 置 参 数 变 量", "score": 1.0 }, { "bbox": [ 300, 725, 389, 743 ], "type": "text", "content": "（ Positional", "score": 1.0 }, { "bbox": [ 409, 726, 474, 742 ], "type": "text", "content": "Parameters", "score": 1.0 }, { "bbox": [ 489, 728, 500, 740 ], "type": "text", "content": "）", "score": 1.0 } ] } ] }, { "bbox": [ 86, 743, 506, 756 ], "type": "text", "angle": 0, "index": 35, "lines": [ { "bbox": [ 86, 740, 508, 759 ], "spans": [ { "bbox": [ 86, 740, 508, 759 ], "type": "text", "content": "通 过 命 令 行 给 程 序 传 递 执 行 参 数", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 12 }, { "para_blocks": [ { "type": "table", "bbox": [ 86, 77, 508, 155 ], "blocks": [ { "bbox": [ 86, 77, 508, 155 ], "lines": [ { "bbox": [ 86, 77, 508, 155 ], "spans": [ { "bbox": [ 86, 77, 508, 155 ], "type": "table", "html": "
可 用 shift 命 令 实 现 位 置 参 数 的 迁 移
专 用 参数 数 变 量 (Special Parameters)
Bash 预 定 义 的 特 殊 变 量
用 户 不 能 修 改 其 值
位置参数变量
", "image_path": "6cc149646954f287832c242a8752e57e10098f5e2a687e55cffbe8b10aa6f709.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "type": "table", "bbox": [ 86, 168, 506, 290 ], "blocks": [ { "bbox": [ 86, 168, 506, 290 ], "lines": [ { "bbox": [ 86, 168, 506, 290 ], "spans": [ { "bbox": [ 86, 168, 506, 290 ], "type": "table", "html": "
是 一 组 特 殊 的 内 置 变 量跟 在 脚 本 名 后 面 的 用 空 格 隔 开 的 每 个 字 符 串$1 表 示 第 1 个 参数 值 , ... , $9 表 示 第 9 个 参数 值${10} 表 示 第 10 个 参数 值, $\\{11\\} 表 示第 11 个 参数 值, ... ...位 置 参 数 的 用 途从 shell 命 令 / 脚 本 的 命 令 行 接 受 参数在 调 用 shell 函数 时 为 其 传 递 参数专用参数变量
", "image_path": "c689524610915dc38010999d2525afdb3d19f903eeea905f416c68390890a59f.jpg" } ] } ], "index": 1, "angle": 0, "type": "table_body" } ], "index": 1 }, { "bbox": [ 86, 304, 500, 318 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 86, 304, 500, 318 ], "spans": [ { "bbox": [ 86, 304, 500, 318 ], "type": "text", "content": "$* 将所有位置参量看成一个字符串(以空格间隔)。" } ] } ], "index": 2 }, { "bbox": [ 87, 321, 500, 334 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 86, 318, 499, 337 ], "spans": [ { "bbox": [ 86, 318, 108, 337 ], "type": "text", "content": "$@", "score": 1.0 }, { "bbox": [ 153, 320, 499, 335 ], "type": "text", "content": "将 每 个 位 置 参 量 看 成 单 独 的 字 符 串 （ 以 空 格 间 隔 ） 。", "score": 1.0 } ] } ] }, { "bbox": [ 96, 336, 499, 350 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 94, 334, 502, 352 ], "spans": [ { "bbox": [ 94, 335, 121, 351 ], "type": "text", "content": "“$*”", "score": 1.0 }, { "bbox": [ 147, 334, 413, 352 ], "type": "text", "content": "将 所 有 位 置 参 量 看 成 一 个 字 符 串 （ 以", "score": 1.0 }, { "bbox": [ 414, 337, 437, 349 ], "type": "inline_equation", "content": "\\$ 105", "score": 0.73 }, { "bbox": [ 438, 334, 502, 352 ], "type": "text", "content": "间 隔 ） 。", "score": 1.0 } ] } ] }, { "bbox": [ 96, 352, 499, 365 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 96, 352, 499, 365 ], "spans": [ { "bbox": [ 96, 353, 122, 364 ], "type": "inline_equation", "content": "\" \\$ 0", "score": 0.73 }, { "bbox": [ 123, 352, 477, 365 ], "type": "text", "content": "将 每 个 位 置 参 量 看 成 单 独 的 字 符 串 （ 以 空 格 间 隔 ）", "score": 1.0 }, { "bbox": [ 493, 358, 499, 364 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 368, 499, 380 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 368, 499, 380 ], "spans": [ { "bbox": [ 87, 368, 499, 380 ], "type": "text", "content": "$0 命令行上输入的 Shell 程序名。" } ] } ], "index": 6 }, { "bbox": [ 87, 383, 499, 396 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 86, 381, 502, 399 ], "spans": [ { "bbox": [ 86, 382, 105, 398 ], "type": "text", "content": "$#", "score": 1.0 }, { "bbox": [ 227, 381, 502, 399 ], "type": "text", "content": "表 示 命 令 行 上 参 数 的 个 数 。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 398, 505, 412 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 398, 505, 412 ], "spans": [ { "bbox": [ 87, 398, 505, 412 ], "type": "text", "content": "进 程 状 态 相 关" } ] } ], "index": 8 }, { "bbox": [ 87, 414, 505, 428 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 412, 508, 430 ], "spans": [ { "bbox": [ 88, 415, 101, 427 ], "type": "inline_equation", "content": "\\$ 7", "score": 0.78 }, { "bbox": [ 150, 412, 508, 430 ], "type": "text", "content": "表 示 上 一 条 命 令 执 行 后 的 返 回 值", "score": 1.0 } ] } ] }, { "bbox": [ 87, 429, 505, 443 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 429, 505, 443 ], "spans": [ { "bbox": [ 87, 429, 505, 443 ], "type": "text", "content": "$$ 当前 进程 的 进程号" } ] } ], "index": 10 }, { "bbox": [ 87, 445, 505, 459 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 88, 445, 506, 460 ], "spans": [ { "bbox": [ 88, 446, 99, 459 ], "type": "inline_equation", "content": "\\$ !", "score": 0.72 }, { "bbox": [ 149, 445, 465, 460 ], "type": "text", "content": "显 示 运 行 在 后 台 的 最 后 一 个 作 业 的", "score": 1.0 }, { "bbox": [ 484, 445, 506, 460 ], "type": "text", "content": "PID", "score": 1.0 } ] } ] }, { "bbox": [ 87, 460, 505, 474 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 460, 505, 474 ], "spans": [ { "bbox": [ 87, 460, 505, 474 ], "type": "text", "content": "$_ 在此之前执行的命令或脚本的最后一个参数" } ] } ], "index": 12 }, { "bbox": [ 87, 476, 135, 489 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 86, 476, 136, 491 ], "spans": [ { "bbox": [ 86, 476, 136, 491 ], "type": "text", "content": "shift 命令", "score": 1.0 } ] } ] }, { "bbox": [ 87, 504, 126, 518 ], "type": "title", "angle": 0, "index": 14, "lines": [ { "bbox": [ 87, 503, 128, 520 ], "spans": [ { "bbox": [ 87, 503, 128, 520 ], "type": "text", "content": "Shift[n]", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 531, 505, 669 ], "blocks": [ { "bbox": [ 86, 531, 505, 669 ], "lines": [ { "bbox": [ 86, 531, 505, 669 ], "spans": [ { "bbox": [ 86, 531, 505, 669 ], "type": "table", "html": "
将位置参量列表依次左移n次，缺省为左移一次
一旦位置参量列表被移动，最左端的那个参数就会从列表中删除
经常与循环结构语句一起使用，以便遍历每一个位置参数
$? : 返回上一条语句或脚本执行的状态
0:成功
1-255
exit命命
exit命令用于退出脚本或当前 Shell
exitn
", "image_path": "9ec227275c1c4324dcfded387055819df045662bdc0dc9f04f63b64055fcbcdc.jpg" } ] } ], "index": 15, "angle": 0, "type": "table_body" } ], "index": 15 }, { "bbox": [ 87, 672, 505, 686 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 672, 505, 686 ], "spans": [ { "bbox": [ 87, 672, 505, 686 ], "type": "text", "content": "n 是一 个从 0 到 255 的整数" } ] } ], "index": 16 }, { "bbox": [ 87, 687, 505, 701 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 687, 506, 702 ], "spans": [ { "bbox": [ 88, 689, 98, 700 ], "type": "text", "content": "0", "score": 1.0 }, { "bbox": [ 120, 687, 506, 702 ], "type": "text", "content": "表 示 成 功 退 出 ， 非 零 表 示 遇 到 某 种 失 败", "score": 1.0 } ] } ] }, { "bbox": [ 87, 703, 505, 716 ], "type": "phonetic", "angle": 0, "lines": [ { "bbox": [ 87, 703, 505, 716 ], "spans": [ { "bbox": [ 87, 703, 505, 716 ], "type": "text", "content": "返回 值 被 保存 在 状态 变 量 $? 中" } ] } ], "index": 18 } ], "discarded_blocks": [ { "bbox": [ 87, 747, 96, 758 ], "type": "page_number", "angle": 0, "index": 19, "lines": [ { "bbox": [ 89, 748, 96, 760 ], "spans": [ { "bbox": [ 89, 748, 96, 760 ], "type": "text", "content": "0", "score": 1.0 } ] } ] }, { "bbox": [ 493, 748, 499, 758 ], "type": "page_number", "angle": 0, "index": 20, "lines": [] } ], "page_size": [ 595, 841 ], "page_idx": 13 }, { "para_blocks": [ { "type": "table", "bbox": [ 87, 77, 508, 201 ], "blocks": [ { "bbox": [ 87, 77, 508, 201 ], "lines": [ { "bbox": [ 87, 77, 508, 201 ], "spans": [ { "bbox": [ 87, 77, 508, 201 ], "type": "table", "html": "
执行正确
1:
通用错误
126:
命令或脚本没有执行行权限
127:
命令没找到
read
", "image_path": "7ebc0b08b0ba05e9f626ccd71980b8644bfc7502ea8ae205e10ab0b80413a7be.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "type": "table", "bbox": [ 87, 214, 506, 339 ], "blocks": [ { "bbox": [ 87, 214, 506, 339 ], "lines": [ { "bbox": [ 87, 214, 506, 339 ], "spans": [ { "bbox": [ 87, 214, 506, 339 ], "type": "table", "html": "
从键盘输入内容为变量赋值
read [-p]" 信息"] [var1 var2 ...]
若省略变量名,则将输入的内容存入REPLY变量
结合不同引号为变量赋值
双引号"：允许通过$符号引用其他变量值
单引号'：禁止引用其他变量值,$视为普通字符
反撇号、`、`：将命令执行的结果输出给变量
只读变量
", "image_path": "90a570c5c9bc35440804fda33806bfd223de41b75ba8fd2ed6c2f8f3dc062d71.jpg" } ] } ], "index": 1, "angle": 0, "type": "table_body" } ], "index": 1 }, { "type": "table", "bbox": [ 88, 352, 507, 460 ], "blocks": [ { "bbox": [ 88, 352, 507, 460 ], "lines": [ { "bbox": [ 88, 352, 507, 460 ], "spans": [ { "bbox": [ 88, 352, 507, 460 ], "type": "table", "html": "
readonlyvariable
使用echo
多行内容中不能出现双引号，否则 echo 提前结束
若确实需要使用双引号，需使用转义字符：\\”
使用here file
.END_可以是任意字符串，只要上下一致即可多行内容中不能出现内容为.END_开始的行，否则 cat 提前结束
", "image_path": "8006282caf9dc331a0d1864f8259db7a2a7d5f8ce3dda142f3e35e932d29ca88.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "bbox": [ 86, 495, 182, 514 ], "type": "title", "angle": 0, "index": 3, "lines": [ { "bbox": [ 86, 495, 183, 516 ], "spans": [ { "bbox": [ 86, 495, 183, 516 ], "type": "text", "content": "2.2 变量声明", "score": 1.0 } ] } ] }, { "bbox": [ 86, 578, 313, 592 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 578, 314, 592 ], "spans": [ { "bbox": [ 89, 578, 314, 592 ], "type": "text", "content": "这里简单举例说明在 Shell 中如何创建一个变量：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 606, 318, 620 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 606, 320, 621 ], "spans": [ { "bbox": [ 89, 606, 320, 621 ], "type": "text", "content": "使用 declare 命令创建一个变量名为 tmp 的变量：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 634, 149, 647 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 632, 151, 650 ], "spans": [ { "bbox": [ 88, 632, 151, 650 ], "type": "text", "content": "declare tmp", "score": 1.0 } ] } ] }, { "bbox": [ 86, 661, 506, 690 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 661, 505, 674 ], "spans": [ { "bbox": [ 88, 661, 505, 674 ], "type": "text", "content": "其实也可以不用 declare 预声明一个变量，直接即用即创建，这里只是告诉你 declare 的", "score": 1.0 } ] }, { "bbox": [ 88, 677, 358, 690 ], "spans": [ { "bbox": [ 88, 677, 358, 690 ], "type": "text", "content": "作用，这在创建其它指定类型的变量（如数组）时会用到。", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 14 }, { "para_blocks": [ { "bbox": [ 86, 84, 166, 103 ], "type": "title", "angle": 0, "index": 0, "lines": [ { "bbox": [ 86, 84, 166, 105 ], "spans": [ { "bbox": [ 86, 84, 166, 105 ], "type": "text", "content": "2.3 变量名", "score": 1.0 } ] } ] }, { "bbox": [ 86, 140, 232, 153 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 141, 231, 153 ], "spans": [ { "bbox": [ 89, 141, 231, 153 ], "type": "text", "content": "变量名的命名须遵循如下规则：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 168, 417, 264 ], "type": "list", "angle": 0, "index": 6, "blocks": [ { "bbox": [ 104, 168, 287, 180 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 114, 164, 289, 183 ], "spans": [ { "bbox": [ 114, 164, 289, 183 ], "type": "text", "content": "首个字符必须为字母（a-z，A-Z）。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 195, 313, 208 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 105, 193, 315, 211 ], "spans": [ { "bbox": [ 105, 193, 315, 211 ], "type": "text", "content": " 中间不能有空格，可以使用下划线（_）。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 222, 214, 235 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 117, 222, 215, 236 ], "spans": [ { "bbox": [ 117, 222, 215, 236 ], "type": "text", "content": "不能使用标点符号。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 250, 417, 264 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 104, 248, 420, 266 ], "spans": [ { "bbox": [ 104, 248, 420, 266 ], "type": "text", "content": " 不能使用 bash 里的关键字（可用 help 命令查看保留关键字）。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 285, 182, 303 ], "type": "title", "angle": 0, "index": 7, "lines": [ { "bbox": [ 86, 284, 183, 305 ], "spans": [ { "bbox": [ 86, 284, 183, 305 ], "type": "text", "content": "2.4 变量赋值", "score": 1.0 } ] } ] }, { "bbox": [ 86, 339, 500, 354 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 86, 338, 500, 355 ], "spans": [ { "bbox": [ 86, 338, 104, 355 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 132, 339, 147, 354 ], "type": "text", "content": "量", "score": 1.0 }, { "bbox": [ 177, 338, 193, 355 ], "type": "text", "content": "赋", "score": 1.0 }, { "bbox": [ 221, 338, 238, 354 ], "type": "text", "content": "值", "score": 1.0 }, { "bbox": [ 273, 339, 284, 354 ], "type": "text", "content": "（", "score": 1.0 }, { "bbox": [ 309, 339, 329, 355 ], "type": "text", "content": "定", "score": 1.0 }, { "bbox": [ 356, 339, 373, 355 ], "type": "text", "content": "义", "score": 1.0 }, { "bbox": [ 401, 338, 418, 355 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 447, 339, 461, 354 ], "type": "text", "content": "量", "score": 1.0 }, { "bbox": [ 491, 339, 500, 354 ], "type": "text", "content": "）", "score": 1.0 } ] } ] }, { "bbox": [ 87, 356, 168, 368 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 355, 170, 370 ], "spans": [ { "bbox": [ 88, 355, 170, 370 ], "type": "text", "content": "varName=Value", "score": 1.0 } ] } ] }, { "bbox": [ 87, 371, 123, 384 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 86, 371, 124, 386 ], "spans": [ { "bbox": [ 86, 371, 124, 386 ], "type": "text", "content": "export", "score": 1.0 } ] } ] }, { "bbox": [ 424, 371, 505, 383 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 424, 371, 506, 384 ], "spans": [ { "bbox": [ 424, 371, 506, 384 ], "type": "text", "content": "varName=Value", "score": 1.0 } ] } ] }, { "bbox": [ 87, 386, 292, 399 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 88, 386, 292, 402 ], "spans": [ { "bbox": [ 88, 386, 102, 401 ], "type": "text", "content": "引", "score": 1.0 }, { "bbox": [ 151, 386, 166, 402 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 214, 386, 229, 402 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 277, 386, 292, 401 ], "type": "text", "content": "量", "score": 1.0 } ] } ] }, { "bbox": [ 452, 387, 505, 398 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 451, 386, 506, 401 ], "spans": [ { "bbox": [ 451, 386, 506, 401 ], "type": "text", "content": "$varName", "score": 1.0 } ] } ] }, { "bbox": [ 86, 402, 499, 415 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 86, 400, 502, 418 ], "spans": [ { "bbox": [ 86, 400, 502, 418 ], "type": "text", "content": "一 般 地 ， 所 有 的 Shell 变 量 都 是 字 符 串 。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 417, 499, 431 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 88, 417, 500, 432 ], "spans": [ { "bbox": [ 88, 417, 500, 432 ], "type": "text", "content": "当 变 量 的 值 仅 仅 包 含 数 字 时 才 允 许 进 行 数 值 计 算 。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 433, 504, 463 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 433, 505, 447 ], "spans": [ { "bbox": [ 88, 433, 505, 447 ], "type": "text", "content": "在较新的 bash 中，可是使用 declare 或 typeset 命令声明变量及其属性，但一般不需要", "score": 1.0 } ] }, { "bbox": [ 88, 449, 499, 462 ], "spans": [ { "bbox": [ 88, 449, 499, 462 ], "type": "text", "content": "声明。而且为了使脚本兼容于不同的 shell，在没有必要的情况下尽量不使用变量声明。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 507, 386, 521 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 506, 389, 523 ], "spans": [ { "bbox": [ 88, 506, 389, 523 ], "type": "text", "content": "变量赋值时，变量名不加美元符号（$，PHP 语言中变量需要）。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 535, 338, 549 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 88, 533, 339, 552 ], "spans": [ { "bbox": [ 88, 533, 111, 552 ], "type": "text", "content": "使用", "score": 1.0 }, { "bbox": [ 111, 536, 121, 546 ], "type": "inline_equation", "content": "=", "score": 0.79 }, { "bbox": [ 121, 533, 339, 552 ], "type": "text", "content": "号赋值运算符，将变量 tmp 赋值为 shiyanlou。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 563, 173, 575 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 88, 563, 173, 576 ], "spans": [ { "bbox": [ 88, 563, 173, 576 ], "type": "text", "content": "# 正确的赋值方法", "score": 1.0 } ] } ] }, { "bbox": [ 87, 591, 164, 603 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 87, 589, 166, 607 ], "spans": [ { "bbox": [ 87, 589, 166, 607 ], "type": "text", "content": "tmp=shiyanlou", "score": 1.0 } ] } ] }, { "bbox": [ 87, 618, 173, 630 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 88, 618, 173, 631 ], "spans": [ { "bbox": [ 88, 618, 173, 631 ], "type": "text", "content": "# 错误的赋值方法", "score": 1.0 } ] } ] }, { "bbox": [ 87, 646, 169, 658 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 88, 645, 171, 661 ], "spans": [ { "bbox": [ 88, 645, 110, 661 ], "type": "text", "content": "tmp", "score": 1.0 }, { "bbox": [ 110, 647, 120, 656 ], "type": "inline_equation", "content": "=", "score": 0.71 }, { "bbox": [ 120, 645, 171, 661 ], "type": "text", "content": "shiyanlou", "score": 1.0 } ] } ] }, { "bbox": [ 86, 673, 255, 686 ], "type": "text", "angle": 0, "index": 23, "lines": [ { "bbox": [ 88, 671, 255, 688 ], "spans": [ { "bbox": [ 88, 671, 255, 688 ], "type": "text", "content": "注意:变量名和等号之间不能有空格。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 701, 355, 714 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 89, 702, 356, 714 ], "spans": [ { "bbox": [ 89, 702, 356, 714 ], "type": "text", "content": "除了直接赋值，还可以用语句给变量赋值，如for 循环中：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 728, 172, 740 ], "type": "text", "angle": 0, "index": 25, "lines": [ { "bbox": [ 88, 727, 172, 741 ], "spans": [ { "bbox": [ 88, 727, 172, 741 ], "type": "text", "content": "for file in `ls /etc`", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 15 }, { "para_blocks": [ { "bbox": [ 88, 113, 182, 132 ], "type": "title", "angle": 0, "index": 0, "lines": [ { "bbox": [ 86, 112, 183, 133 ], "spans": [ { "bbox": [ 86, 112, 183, 133 ], "type": "text", "content": "2.5 变量取值", "score": 1.0 } ] } ] }, { "bbox": [ 86, 169, 400, 184 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 169, 399, 183 ], "spans": [ { "bbox": [ 89, 169, 399, 183 ], "type": "text", "content": "变量的名字就是变量保存值的地方。引用变量的值就叫做变量取值。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 195, 505, 226 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 196, 505, 210 ], "spans": [ { "bbox": [ 89, 196, 505, 210 ], "type": "text", "content": "如果 variable 是一个变量的名字，那么 $variable 就是引用这个变量的值，即这变量所包", "score": 1.0 } ] }, { "bbox": [ 88, 211, 138, 226 ], "spans": [ { "bbox": [ 88, 211, 138, 226 ], "type": "text", "content": "含的数据。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 239, 505, 269 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 239, 505, 253 ], "spans": [ { "bbox": [ 88, 239, 192, 253 ], "type": "text", "content": "$variable 事实上只是", "score": 1.0 }, { "bbox": [ 192, 240, 200, 252 ], "type": "inline_equation", "content": "\\$ 1", "score": 0.51 }, { "bbox": [ 200, 239, 505, 253 ], "type": "text", "content": "{variable} 的简写形式。在某些上下文中 $variable 可能会引起错", "score": 1.0 } ] }, { "bbox": [ 88, 255, 258, 269 ], "spans": [ { "bbox": [ 88, 255, 258, 269 ], "type": "text", "content": "误，这时候就需要用 ${variable} 了。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 282, 505, 312 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 282, 505, 296 ], "spans": [ { "bbox": [ 89, 282, 248, 296 ], "type": "text", "content": "读取变量的值，使用 echo 命令和", "score": 1.0 }, { "bbox": [ 248, 282, 257, 295 ], "type": "inline_equation", "content": "\\$ 9", "score": 0.74 }, { "bbox": [ 257, 282, 289, 296 ], "type": "text", "content": "符号（", "score": 1.0 }, { "bbox": [ 289, 282, 298, 295 ], "type": "inline_equation", "content": "\\$ 5", "score": 0.54 }, { "bbox": [ 299, 282, 505, 296 ], "type": "text", "content": "符号用于表示引用一个变量的值，初学者经", "score": 1.0 } ] }, { "bbox": [ 89, 298, 160, 312 ], "spans": [ { "bbox": [ 89, 298, 160, 312 ], "type": "text", "content": "常忘记输入）：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 326, 145, 341 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 87, 322, 145, 342 ], "spans": [ { "bbox": [ 87, 322, 145, 342 ], "type": "text", "content": "echo $tmp", "score": 1.0 } ] } ] }, { "bbox": [ 87, 353, 196, 368 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 352, 196, 369 ], "spans": [ { "bbox": [ 88, 352, 132, 369 ], "type": "text", "content": "myname", "score": 1.0 }, { "bbox": [ 132, 355, 139, 364 ], "type": "inline_equation", "content": "=", "score": 0.57 }, { "bbox": [ 139, 352, 196, 369 ], "type": "text", "content": "\"shiyanlou\"", "score": 1.0 } ] } ] }, { "bbox": [ 88, 380, 167, 395 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 380, 167, 396 ], "spans": [ { "bbox": [ 88, 380, 167, 396 ], "type": "text", "content": "echo $myname", "score": 1.0 } ] } ] }, { "bbox": [ 88, 408, 174, 422 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 407, 176, 424 ], "spans": [ { "bbox": [ 88, 407, 176, 424 ], "type": "text", "content": "echo ${myname}", "score": 1.0 } ] } ] }, { "bbox": [ 88, 436, 201, 449 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 434, 202, 451 ], "spans": [ { "bbox": [ 88, 434, 202, 451 ], "type": "text", "content": "echo ${myname}Good", "score": 1.0 } ] } ] }, { "bbox": [ 88, 464, 193, 476 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 462, 194, 478 ], "spans": [ { "bbox": [ 88, 462, 194, 478 ], "type": "text", "content": "echo $mynameGood", "score": 1.0 } ] } ] }, { "bbox": [ 88, 491, 173, 504 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 87, 491, 174, 506 ], "spans": [ { "bbox": [ 87, 491, 132, 506 ], "type": "text", "content": "myname", "score": 1.0 }, { "bbox": [ 132, 493, 139, 502 ], "type": "inline_equation", "content": "=", "score": 0.59 }, { "bbox": [ 140, 491, 174, 506 ], "type": "text", "content": "\"miao\"", "score": 1.0 } ] } ] }, { "bbox": [ 88, 518, 174, 532 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 88, 517, 176, 534 ], "spans": [ { "bbox": [ 88, 517, 176, 534 ], "type": "text", "content": "echo ${myname}", "score": 1.0 } ] } ] }, { "bbox": [ 86, 574, 504, 602 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 89, 574, 504, 587 ], "spans": [ { "bbox": [ 89, 574, 504, 587 ], "type": "text", "content": "使用readonly 命令可以将变量定义为只读变量，只读变量的值不能被改变。 下面的例子", "score": 1.0 } ] }, { "bbox": [ 89, 589, 231, 602 ], "spans": [ { "bbox": [ 89, 589, 231, 602 ], "type": "text", "content": "尝试更改只读变量，结果报错：", "score": 1.0 } ] } ] }, { "bbox": [ 88, 617, 147, 629 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 88, 617, 148, 629 ], "spans": [ { "bbox": [ 88, 617, 148, 629 ], "type": "text", "content": "#!/bin/bash", "score": 1.0 } ] } ] }, { "bbox": [ 88, 645, 264, 658 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 88, 644, 264, 661 ], "spans": [ { "bbox": [ 88, 644, 264, 661 ], "type": "text", "content": "myUrl=\"http://www.shiyanlou.com\"", "score": 1.0 } ] } ] }, { "bbox": [ 88, 672, 166, 686 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 671, 167, 687 ], "spans": [ { "bbox": [ 88, 671, 167, 687 ], "type": "text", "content": "readonly myUrl", "score": 1.0 } ] } ] }, { "bbox": [ 88, 700, 256, 714 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 698, 257, 714 ], "spans": [ { "bbox": [ 88, 698, 257, 714 ], "type": "text", "content": "myUrl=http://www.shiyanlou.com", "score": 1.0 } ] } ] }, { "bbox": [ 88, 727, 206, 740 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 89, 728, 205, 740 ], "spans": [ { "bbox": [ 89, 728, 205, 740 ], "type": "text", "content": "变量的查询、显示和取消", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 16 }, { "para_blocks": [ { "type": "table", "bbox": [ 86, 77, 508, 186 ], "blocks": [ { "bbox": [ 86, 77, 508, 186 ], "lines": [ { "bbox": [ 86, 77, 508, 186 ], "spans": [ { "bbox": [ 86, 77, 508, 186 ], "type": "table", "html": "
显示当前已经定义的所有变量
所有有环境变量：env
所有变量和函数（包括环境变量）：set
显示某些个变量的值
echo $NAME1[$NAME2]......]
取消变量的声明或赋值
unset<NAME>
", "image_path": "95e0c0efd0ddd138f4bd08fd9135cbe1c711592da80a5509dd543553a485d65f.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "bbox": [ 87, 215, 255, 229 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 215, 255, 230 ], "spans": [ { "bbox": [ 88, 215, 255, 230 ], "type": "text", "content": "1. 子进程（Child Process）的本质", "score": 1.0 } ] } ] }, { "bbox": [ 104, 243, 504, 300 ], "type": "list", "angle": 0, "index": 4, "blocks": [ { "bbox": [ 104, 243, 493, 257 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 105, 243, 494, 258 ], "spans": [ { "bbox": [ 105, 243, 494, 258 ], "type": "text", "content": " 当你在 Shell 中运行 bash -c 'command' 时，会启动一个 全新的子 Shell 进程。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 270, 504, 300 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 114, 270, 506, 285 ], "spans": [ { "bbox": [ 114, 270, 506, 285 ], "type": "text", "content": "子进程会继承父进程的 环境变量（export 导出的变量），但 不会继承父进程的私", "score": 1.0 } ] }, { "bbox": [ 123, 285, 163, 301 ], "spans": [ { "bbox": [ 123, 285, 163, 301 ], "type": "text", "content": "有变量。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 87, 313, 112, 327 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 313, 113, 330 ], "spans": [ { "bbox": [ 88, 313, 113, 330 ], "type": "text", "content": "引用", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 340, 504, 432 ], "blocks": [ { "bbox": [ 86, 340, 504, 432 ], "lines": [ { "bbox": [ 86, 340, 504, 432 ], "spans": [ { "bbox": [ 86, 340, 504, 432 ], "type": "table", "html": "
在bash中，有些字符具有特殊含义，如果需要忽略这些字符的特殊含义，就必须使用引用
引用可以通过下面三种方式实现
使用转义字符:\\
使用单引号:''
使用双引号:“”
", "image_path": "382eeeb7bc44518f29fe28eb4ba7441d8a2de580b94d3bb4f0578a6bd7f5932f.jpg" } ] } ], "index": 6, "angle": 0, "type": "table_body" } ], "index": 6 }, { "bbox": [ 86, 435, 440, 449 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 434, 440, 449 ], "spans": [ { "bbox": [ 88, 434, 440, 449 ], "type": "text", "content": "转义字符的引用方法就是直接在字符前加反斜杠。例：\\$，\\‘，\\“，\\\\，\\ ，\\!", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 461, 505, 523 ], "blocks": [ { "bbox": [ 86, 461, 505, 523 ], "lines": [ { "bbox": [ 86, 461, 505, 523 ], "spans": [ { "bbox": [ 86, 461, 505, 523 ], "type": "table", "html": "
强引用
单引号对是 强 引 用
单引号对中的字符都将作为普通字符,但不允许出现另外的单引号。
弱引用
", "image_path": "5d1a7e6ca3e33eaa372a2593a5e7578d40354388a8cc066eee75fc8ff9f984da.jpg" } ] } ], "index": 8, "angle": 0, "type": "table_body" } ], "index": 8 }, { "bbox": [ 87, 525, 174, 538 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 89, 525, 174, 539 ], "spans": [ { "bbox": [ 89, 525, 174, 539 ], "type": "text", "content": "双引号对是弱引用", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 539, 505, 616 ], "blocks": [ { "bbox": [ 86, 539, 505, 616 ], "lines": [ { "bbox": [ 86, 539, 505, 616 ], "spans": [ { "bbox": [ 86, 539, 505, 616 ], "type": "table", "html": "
双引号对中的部分字符仍保留特殊含义
$（ 美元 符 号）-变量 扩展
（ 反 引 号）-命 令 替 换
（ 反 斜 线）-禁止 单个 字符 扩展
！（ 叹 号）-历史 命 令 替 换
", "image_path": "4cb13fa48e934209dac52184942f843c48f9c346d6a45f716d4fe7035af94365.jpg" } ] } ], "index": 10, "angle": 0, "type": "table_body" } ], "index": 10 }, { "bbox": [ 86, 652, 181, 671 ], "type": "title", "angle": 0, "index": 11, "lines": [ { "bbox": [ 86, 651, 184, 673 ], "spans": [ { "bbox": [ 86, 651, 184, 673 ], "type": "text", "content": "4.1 环境变量", "score": 1.0 } ] } ] }, { "bbox": [ 86, 708, 505, 753 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 89, 708, 505, 721 ], "spans": [ { "bbox": [ 89, 708, 505, 721 ], "type": "text", "content": "简单理解了变量的概念，就很容易理解环境变量了。环境变量的作用域比自定义变量的要", "score": 1.0 } ] }, { "bbox": [ 89, 724, 505, 736 ], "spans": [ { "bbox": [ 89, 724, 505, 736 ], "type": "text", "content": "大，如Shell 的环境变量作用于自身和它的子进程。在所有的 UNIX 和类UNIX 系统中，每", "score": 1.0 } ] }, { "bbox": [ 89, 740, 505, 752 ], "spans": [ { "bbox": [ 89, 740, 505, 752 ], "type": "text", "content": "个进程都有其各自的环境变量设置，且默认情况下，当一个进程被创建时，除了创建过程", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 17 }, { "para_blocks": [ { "bbox": [ 86, 79, 505, 109 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 505, 92 ], "spans": [ { "bbox": [ 89, 79, 505, 92 ], "type": "text", "content": "中明确指定的话，它将继承其父进程的绝大部分环境设置。Shell 程序也作为一个进程运行", "score": 1.0 } ] }, { "bbox": [ 89, 94, 499, 108 ], "spans": [ { "bbox": [ 89, 94, 499, 108 ], "type": "text", "content": "在操作系统之上，而我们在 Shell 中运行的大部分命令都将以 Shell 的子进程的方式运行。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 121, 264, 135 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 121, 263, 135 ], "spans": [ { "bbox": [ 88, 121, 263, 135 ], "type": "text", "content": "通常我们会涉及到的变量类型有三种：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 149, 504, 233 ], "type": "list", "angle": 0, "index": 5, "blocks": [ { "bbox": [ 104, 149, 504, 178 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 123, 148, 505, 163 ], "spans": [ { "bbox": [ 123, 148, 505, 163 ], "type": "text", "content": "当前 Shell 进程私有用户自定义变量，如上面我们创建的 tmp 变量，只在当前", "score": 1.0 } ] }, { "bbox": [ 124, 165, 189, 178 ], "spans": [ { "bbox": [ 124, 165, 189, 178 ], "type": "text", "content": "Shell 中有效。", "score": 1.0 } ] } ] }, { "bbox": [ 105, 193, 230, 206 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 105, 192, 232, 206 ], "spans": [ { "bbox": [ 105, 192, 232, 206 ], "type": "text", "content": " Shell 本身内建的变量。", "score": 1.0 } ] } ] }, { "bbox": [ 105, 221, 267, 233 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 104, 221, 267, 233 ], "spans": [ { "bbox": [ 104, 221, 267, 233 ], "type": "text", "content": " 从自定义变量导出的环境变量。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 248, 506, 276 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 89, 248, 505, 262 ], "spans": [ { "bbox": [ 89, 248, 505, 262 ], "type": "text", "content": "也有三个与上述三种环境变量相关的命令：set，env，export。这三个命令很相似，都是", "score": 1.0 } ] }, { "bbox": [ 89, 264, 400, 276 ], "spans": [ { "bbox": [ 89, 264, 400, 276 ], "type": "text", "content": "用于打印环境变量信息，区别在于涉及的变量范围不同。详见下表：", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 87, 277, 454, 475 ], "blocks": [ { "bbox": [ 87, 277, 454, 475 ], "lines": [ { "bbox": [ 87, 277, 454, 475 ], "spans": [ { "bbox": [ 87, 277, 454, 475 ], "type": "table", "html": "
命令说明
set显示当前 Shell 所有变量，包括其内建环境变量（与 Shell 外观等相关），用户自定义变量及导出的环境变量。
env显示与当前用户相关的环境变量，还可以让命令在指定环境中运行。
export显示从 Shell 中导出成环境变量的变量，也能通过它将自定义变量导出为环境变量。
", "image_path": "f0efc7dd784b88be9736ab59105317c3b6b447849dfa4fa723f9ded6d21da12a.jpg" } ] } ], "index": 7, "angle": 0, "type": "table_body" } ], "index": 7 }, { "bbox": [ 86, 487, 246, 501 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 486, 246, 503 ], "spans": [ { "bbox": [ 88, 486, 246, 503 ], "type": "text", "content": "vimdiff env.txt export.txt set.txt", "score": 1.0 } ] } ] }, { "bbox": [ 86, 543, 505, 571 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 543, 505, 557 ], "spans": [ { "bbox": [ 88, 543, 505, 557 ], "type": "text", "content": "使用vimdiff 工具比较导出的几个文件的内容，退出 vimdiff 需要按下 Esc 后输入 :q 即可", "score": 1.0 } ] }, { "bbox": [ 86, 557, 118, 574 ], "spans": [ { "bbox": [ 86, 557, 118, 574 ], "type": "text", "content": "退出。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 586, 506, 647 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 89, 587, 505, 598 ], "spans": [ { "bbox": [ 89, 587, 505, 598 ], "type": "text", "content": "关于哪些变量是环境变量，可以简单地理解成在当前进程的子进程有效则为环境变量，否", "score": 1.0 } ] }, { "bbox": [ 89, 602, 505, 614 ], "spans": [ { "bbox": [ 89, 602, 505, 614 ], "type": "text", "content": "则不是（有些人也将所有变量统称为环境变量，只是以全局环境变量和局部环境变量进行", "score": 1.0 } ] }, { "bbox": [ 88, 618, 506, 632 ], "spans": [ { "bbox": [ 88, 618, 506, 632 ], "type": "text", "content": "区分，我们只要理解它们的实质区别即可）。我们这里用 export 命令来体会一下，先在", "score": 1.0 } ] }, { "bbox": [ 88, 633, 505, 647 ], "spans": [ { "bbox": [ 88, 633, 505, 647 ], "type": "text", "content": "Shell 中设置一个变量 temp=shiyanlou，然后再新创建一个子 Shell 查看 temp 变量的值：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 688, 133, 701 ], "type": "title", "angle": 0, "index": 11, "lines": [ { "bbox": [ 88, 688, 133, 703 ], "spans": [ { "bbox": [ 88, 688, 133, 703 ], "type": "text", "content": "环境变量", "score": 1.0 } ] } ] }, { "bbox": [ 86, 743, 500, 756 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 88, 743, 499, 756 ], "spans": [ { "bbox": [ 88, 743, 499, 756 ], "type": "text", "content": "环 境 变 量 定 义 Shell 的 运 行 环 境 ， 保 证 Shell 命 令 的 正 确 执 行 。", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 18 }, { "para_blocks": [ { "bbox": [ 86, 79, 499, 109 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 501, 92 ], "spans": [ { "bbox": [ 89, 79, 501, 92 ], "type": "text", "content": "Shell 用环境变量来 确 定 查找路 径 、 注册目 录 、终端类型 、终端名 称 、 用 户 名 等 。", "score": 1.0 } ] }, { "bbox": [ 89, 95, 498, 106 ], "spans": [ { "bbox": [ 89, 95, 498, 106 ], "type": "text", "content": "所有环境变量都是全局变量（即可以传递给 Shell 的子进程），并可以由用户重新设置。", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 86, 122, 594, 587 ], "blocks": [ { "bbox": [ 86, 122, 594, 587 ], "lines": [ { "bbox": [ 86, 122, 594, 587 ], "spans": [ { "bbox": [ 86, 122, 594, 587 ], "type": "table", "html": "
变量名含义
HOME用户主目录
LOGNAME登录名
USER用户名，与登录名相同
PWD当前目录/工作目录名
MAIL用户的邮箱路径名
HOSTNAME计算机的主机名
INPUTRC默认的键盘映像
SHELL用户所使用的 shell 的路径名
LANG默认语言
HISTSIZEhistory 所能记住的命令的最多个数
PATHshell 查找用户输入命令的路径(目录列表)
PS1、PS2shell 一级、二级命令提示符
", "image_path": "8c70ec3f3467dd8dc326a26c22122471c617cb64c4965b4669e28ec8965a08c9.jpg" } ] } ], "index": 1, "angle": 0, "type": "table_body" } ], "index": 1 }, { "bbox": [ 86, 628, 399, 641 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 628, 399, 643 ], "spans": [ { "bbox": [ 89, 628, 399, 643 ], "type": "text", "content": "注意：为了与普通变量区分，通常我们习惯将环境变量名设为大写。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 655, 151, 667 ], "type": "title", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 655, 151, 669 ], "spans": [ { "bbox": [ 88, 655, 151, 669 ], "type": "text", "content": "4.2 变量时效", "score": 1.0 } ] } ] }, { "bbox": [ 86, 682, 504, 711 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 682, 504, 697 ], "spans": [ { "bbox": [ 89, 682, 504, 697 ], "type": "text", "content": "当关机后，或者关闭当前的 shell 之后，环境变量就失效了。怎样才能让环境变量永久生", "score": 1.0 } ] }, { "bbox": [ 88, 698, 119, 713 ], "spans": [ { "bbox": [ 88, 698, 119, 713 ], "type": "text", "content": "效呢？", "score": 1.0 } ] } ] }, { "bbox": [ 86, 726, 324, 739 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 726, 324, 740 ], "spans": [ { "bbox": [ 88, 726, 324, 740 ], "type": "text", "content": "按变量的生存周期来划分，Linux 变量可分为两类：", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 19 }, { "para_blocks": [ { "bbox": [ 105, 79, 426, 119 ], "type": "list", "angle": 0, "index": 2, "blocks": [ { "bbox": [ 105, 79, 330, 91 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 107, 79, 331, 93 ], "spans": [ { "bbox": [ 107, 79, 331, 93 ], "type": "text", "content": "1. 永久的：需要修改配置文件，变量永久生效；", "score": 1.0 } ] } ] }, { "bbox": [ 105, 106, 426, 119 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 105, 106, 427, 121 ], "spans": [ { "bbox": [ 105, 106, 427, 121 ], "type": "text", "content": "2. 临时的：使用 export 命令行声明即可，变量在关闭 shell 时失效。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 134, 504, 163 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 134, 505, 148 ], "spans": [ { "bbox": [ 88, 134, 505, 148 ], "type": "text", "content": "这里介绍两个重要文件 /etc/bashrc（有的 Linux 没有这个文件） 和 /etc/profile ，它们分", "score": 1.0 } ] }, { "bbox": [ 88, 150, 502, 163 ], "spans": [ { "bbox": [ 88, 150, 502, 163 ], "type": "text", "content": "别存放的是 shell 变量和环境变量。还有要注意区别的是每个用户目录下的一个隐藏文件：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 177, 505, 237 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 177, 505, 191 ], "spans": [ { "bbox": [ 88, 177, 505, 191 ], "type": "text", "content": "这个 .profile 只对当前用户永久生效。因为它保存在当前用户的 Home 目录下，当切换用", "score": 1.0 } ] }, { "bbox": [ 88, 191, 505, 207 ], "spans": [ { "bbox": [ 88, 191, 505, 207 ], "type": "text", "content": "户时，工作目录可能一并被切换到对应的目录中，这个文件就无法生效。而写在 /etc/pro", "score": 1.0 } ] }, { "bbox": [ 88, 209, 505, 222 ], "spans": [ { "bbox": [ 88, 209, 505, 222 ], "type": "text", "content": "file 里面的是对所有用户永久生效，所以如果想要添加一个永久生效的环境变量，只需要", "score": 1.0 } ] }, { "bbox": [ 88, 225, 320, 238 ], "spans": [ { "bbox": [ 88, 225, 320, 238 ], "type": "text", "content": "打开 /etc/profile，在最后加上要添加的环境变量。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 258, 193, 276 ], "type": "title", "angle": 0, "index": 5, "lines": [ { "bbox": [ 86, 256, 195, 278 ], "spans": [ { "bbox": [ 86, 256, 195, 278 ], "type": "text", "content": "4.3 PATH 变量", "score": 1.0 } ] } ] }, { "bbox": [ 86, 313, 504, 373 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 89, 313, 504, 326 ], "spans": [ { "bbox": [ 89, 313, 504, 326 ], "type": "text", "content": "你可能很早之前就有疑问，我们在 Shell 中输入一个命令，Shell 是怎么知道去哪找到这个", "score": 1.0 } ] }, { "bbox": [ 89, 329, 506, 342 ], "spans": [ { "bbox": [ 89, 329, 506, 342 ], "type": "text", "content": "命令然后执行的呢？这是通过环境变量 PATH 来进行搜索的，熟悉 Windows 的用户可能", "score": 1.0 } ] }, { "bbox": [ 88, 345, 505, 358 ], "spans": [ { "bbox": [ 88, 345, 505, 358 ], "type": "text", "content": "知道 Windows 中的也是有这么一个 PATH 环境变量。这个 PATH 里面就保存了 Shell 中执", "score": 1.0 } ] }, { "bbox": [ 88, 360, 189, 373 ], "spans": [ { "bbox": [ 88, 360, 189, 373 ], "type": "text", "content": "行的命令的搜索路径。", "score": 1.0 } ] } ] }, { "bbox": [ 105, 388, 198, 401 ], "type": "title", "angle": 0, "index": 7, "lines": [ { "bbox": [ 107, 386, 198, 402 ], "spans": [ { "bbox": [ 107, 386, 198, 402 ], "type": "text", "content": "1. 查看 PATH 内容", "score": 1.0 } ] } ] }, { "bbox": [ 86, 415, 220, 428 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 89, 415, 220, 428 ], "spans": [ { "bbox": [ 89, 415, 220, 428 ], "type": "text", "content": "查看PATH 环境变量的内容：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 443, 149, 454 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 443, 149, 456 ], "spans": [ { "bbox": [ 88, 443, 149, 456 ], "type": "text", "content": "echo $PATH", "score": 1.0 } ] } ] }, { "bbox": [ 86, 498, 231, 511 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 89, 499, 232, 513 ], "spans": [ { "bbox": [ 89, 499, 232, 513 ], "type": "text", "content": "默认情况下你会看到如下输出：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 526, 480, 555 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 87, 523, 482, 540 ], "spans": [ { "bbox": [ 87, 523, 482, 540 ], "type": "text", "content": "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/", "score": 1.0 } ] }, { "bbox": [ 86, 543, 124, 555 ], "spans": [ { "bbox": [ 86, 543, 124, 555 ], "type": "text", "content": "games", "score": 1.0 } ] } ] }, { "bbox": [ 86, 597, 504, 656 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 89, 597, 503, 609 ], "spans": [ { "bbox": [ 89, 597, 503, 609 ], "type": "text", "content": "如果你还记得 Linux 目录结构那一节的内容，你就应该知道上面这些目录下放的是哪一类", "score": 1.0 } ] }, { "bbox": [ 88, 612, 505, 625 ], "spans": [ { "bbox": [ 88, 612, 505, 625 ], "type": "text", "content": "文件了。通常这一类目录下放的都是可执行文件，当我们在 Shell 中执行一个命令时，系", "score": 1.0 } ] }, { "bbox": [ 89, 629, 505, 640 ], "spans": [ { "bbox": [ 89, 629, 505, 640 ], "type": "text", "content": "统就会按照 PATH 中设定的路径按照顺序依次到目录中去查找，如果存在同名的命令，则", "score": 1.0 } ] }, { "bbox": [ 88, 644, 179, 656 ], "spans": [ { "bbox": [ 88, 644, 179, 656 ], "type": "text", "content": "执行先找到的那个。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 671, 504, 715 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 89, 671, 504, 684 ], "spans": [ { "bbox": [ 89, 671, 504, 684 ], "type": "text", "content": "回到上一级目录，也就是 shiyanlou 家目录，当再想运行那两个程序时，会发现提示命令", "score": 1.0 } ] }, { "bbox": [ 89, 687, 505, 699 ], "spans": [ { "bbox": [ 89, 687, 505, 699 ], "type": "text", "content": "找不到，除非加上命令的完整路径，但那样很不方便，如何做到像使用系统命令一样执行", "score": 1.0 } ] }, { "bbox": [ 89, 703, 471, 715 ], "spans": [ { "bbox": [ 89, 703, 471, 715 ], "type": "text", "content": "自己创建的脚本文件或者程序呢？那就要将命令所在路径添加到PATH 环境变量了。", "score": 1.0 } ] } ] }, { "bbox": [ 105, 729, 208, 742 ], "type": "title", "angle": 0, "index": 14, "lines": [ { "bbox": [ 105, 729, 209, 744 ], "spans": [ { "bbox": [ 105, 729, 209, 744 ], "type": "text", "content": "3. 自定义 PATH 变量", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 20 }, { "para_blocks": [ { "bbox": [ 86, 79, 506, 109 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 505, 92 ], "spans": [ { "bbox": [ 89, 79, 505, 92 ], "type": "text", "content": "现在，我们添加自定义路径到“ PATH ”环境变量。在前面我们应该注意到 PATH 里面的路", "score": 1.0 } ] }, { "bbox": [ 89, 95, 365, 107 ], "spans": [ { "bbox": [ 89, 95, 365, 107 ], "type": "text", "content": "径是以: 作为分割符的，所以我们可以这样添加自定义路径：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 121, 274, 136 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 121, 276, 138 ], "spans": [ { "bbox": [ 88, 121, 276, 138 ], "type": "text", "content": "PATH=$PATH:/home/shiyanlou/mybin", "score": 1.0 } ] } ] }, { "bbox": [ 86, 149, 510, 211 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 151, 509, 162 ], "spans": [ { "bbox": [ 89, 151, 509, 162 ], "type": "text", "content": "你可能会意识到这样还并没有很好的解决问题，因为我给 PATH 环境变量追加了一个路径，", "score": 1.0 } ] }, { "bbox": [ 89, 166, 505, 178 ], "spans": [ { "bbox": [ 89, 166, 505, 178 ], "type": "text", "content": "它也只是在当前 Shell 有效，我一旦退出终端，再打开就会发现又失效了。有没有方法让", "score": 1.0 } ] }, { "bbox": [ 88, 180, 506, 194 ], "spans": [ { "bbox": [ 88, 180, 506, 194 ], "type": "text", "content": "添加的环境变量全局有效？或者每次启动 Shell 时自动执行上面添加自定义路径到 PATH", "score": 1.0 } ] }, { "bbox": [ 89, 196, 357, 209 ], "spans": [ { "bbox": [ 89, 196, 357, 209 ], "type": "text", "content": "的命令？下面我们就来说说后一种方式——让它自动执行。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 224, 508, 300 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 89, 224, 505, 237 ], "spans": [ { "bbox": [ 89, 224, 505, 237 ], "type": "text", "content": "在每个用户的 home 目录中有一个 Shell 每次启动时会默认执行一个配置脚本，以初始化", "score": 1.0 } ] }, { "bbox": [ 88, 239, 505, 252 ], "spans": [ { "bbox": [ 88, 239, 505, 252 ], "type": "text", "content": "环境，包括添加一些用户自定义环境变量等等。实验楼的环境使用的 Shell 是 zsh，它的配", "score": 1.0 } ] }, { "bbox": [ 89, 256, 503, 269 ], "spans": [ { "bbox": [ 89, 256, 503, 269 ], "type": "text", "content": "置文件是 .zshrc，相应的如果使用的 Shell 是 Bash，则配置文件为 .bashrc。它们在 etc", "score": 1.0 } ] }, { "bbox": [ 90, 271, 506, 284 ], "spans": [ { "bbox": [ 90, 271, 506, 284 ], "type": "text", "content": "下还都有一个或多个全局的配置文件，不过我们一般只修改用户目录下的配置文件。Shell", "score": 1.0 } ] }, { "bbox": [ 89, 287, 435, 300 ], "spans": [ { "bbox": [ 89, 287, 435, 300 ], "type": "text", "content": "的种类有很多，可以使用cat /etc/shells 命令查看当前系统已安装的 Shell。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 314, 348, 327 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 315, 349, 327 ], "spans": [ { "bbox": [ 89, 315, 349, 327 ], "type": "text", "content": "我们可以简单地使用下面命令直接添加内容到.zshrc 中：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 341, 357, 354 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 87, 338, 357, 358 ], "spans": [ { "bbox": [ 87, 338, 357, 358 ], "type": "text", "content": "echo \"PATH=$PATH:/home/shiyanlou/mybin\" >> .zshrc", "score": 1.0 } ] } ] }, { "bbox": [ 86, 396, 507, 442 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 89, 396, 505, 410 ], "spans": [ { "bbox": [ 89, 396, 143, 410 ], "type": "text", "content": "上述命令中", "score": 1.0 }, { "bbox": [ 143, 397, 159, 408 ], "type": "inline_equation", "content": "> >", "score": 0.85 }, { "bbox": [ 160, 396, 483, 410 ], "type": "text", "content": "表示将标准输出以追加的方式重定向到一个文件中，注意前面用到的", "score": 1.0 }, { "bbox": [ 483, 397, 493, 408 ], "type": "inline_equation", "content": ">", "score": 0.77 }, { "bbox": [ 493, 396, 505, 410 ], "type": "text", "content": "是", "score": 1.0 } ] }, { "bbox": [ 89, 412, 505, 425 ], "spans": [ { "bbox": [ 89, 412, 505, 425 ], "type": "text", "content": "以覆盖的方式重定向到一个文件中，使用的时候一定要注意分辨。在指定文件不存在的情", "score": 1.0 } ] }, { "bbox": [ 89, 428, 200, 441 ], "spans": [ { "bbox": [ 89, 428, 200, 441 ], "type": "text", "content": "况下都会创建新的文件。", "score": 1.0 } ] } ] }, { "bbox": [ 105, 455, 198, 469 ], "type": "title", "angle": 0, "index": 7, "lines": [ { "bbox": [ 105, 454, 199, 470 ], "spans": [ { "bbox": [ 105, 454, 199, 470 ], "type": "text", "content": "4. 修改 PATH 变量", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 497, 455, 747 ], "blocks": [ { "bbox": [ 87, 483, 248, 496 ], "lines": [ { "bbox": [ 89, 483, 248, 497 ], "spans": [ { "bbox": [ 89, 483, 248, 497 ], "type": "text", "content": "PATH 变量的修改有以下几种方式：", "score": 1.0 } ] } ], "index": 8, "angle": 0, "type": "table_caption" }, { "bbox": [ 88, 497, 455, 747 ], "lines": [ { "bbox": [ 88, 497, 455, 747 ], "spans": [ { "bbox": [ 88, 497, 455, 747 ], "type": "table", "html": "
变量设置方式说明
${变量名#匹配字串}从头向后开始匹配，删除符合匹配字串的最短数据
${变量名##匹配字串}从头向后开始匹配，删除符合匹配字串的最长数据
${变量名%匹配字串}从尾向前开始匹配，删除符合匹配字串的最短数据
${变量名%%匹配字串}从尾向前开始匹配，删除符合匹配字串的最长数据
${变量名/旧的字串/新的字串}将符合旧字串的第一个字串替换为新的字串
${变量名//旧的字串/新的字串}将符合旧字串的全部字串替换为新的字串
", "image_path": "80b2d5c1c43c40f8f14bddcdb09334a88b6612aadb8c535afbaa004d5e1d8246.jpg" } ] } ], "index": 9, "angle": 0, "type": "table_body" } ], "index": 9 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 21 }, { "para_blocks": [ { "type": "table", "bbox": [ 88, 76, 454, 222 ], "blocks": [ { "bbox": [ 88, 76, 454, 222 ], "lines": [], "index": 0, "angle": 0, "type": "table_body", "lines_deleted": true } ], "index": 0 }, { "bbox": [ 86, 234, 172, 248 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 235, 171, 248 ], "spans": [ { "bbox": [ 89, 235, 171, 248 ], "type": "text", "content": "4.4 环境变量删除", "score": 1.0 } ] } ] }, { "bbox": [ 87, 262, 274, 275 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 262, 276, 276 ], "spans": [ { "bbox": [ 89, 262, 276, 276 ], "type": "text", "content": "可以使用unset 命令删除一个环境变量：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 290, 158, 303 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 87, 290, 160, 305 ], "spans": [ { "bbox": [ 87, 290, 160, 305 ], "type": "text", "content": "unset mypath", "score": 1.0 } ] } ] }, { "bbox": [ 86, 317, 192, 330 ], "type": "title", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 317, 193, 332 ], "spans": [ { "bbox": [ 88, 317, 193, 332 ], "type": "text", "content": "4.5 环境变量立即生效", "score": 1.0 } ] } ] }, { "bbox": [ 86, 344, 504, 389 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 345, 505, 358 ], "spans": [ { "bbox": [ 89, 345, 505, 358 ], "type": "text", "content": "前面我们在 Shell 中修改了一个配置脚本文件之后（比如 zsh 的配置文件 home 目录下", "score": 1.0 } ] }, { "bbox": [ 88, 360, 505, 374 ], "spans": [ { "bbox": [ 88, 360, 505, 374 ], "type": "text", "content": "的.zshrc），每次都要退出终端重新打开甚至重启主机之后其才能生效，很是麻烦，我们", "score": 1.0 } ] }, { "bbox": [ 89, 376, 290, 389 ], "spans": [ { "bbox": [ 89, 376, 290, 389 ], "type": "text", "content": "可以使用source 命令来让其立即生效，如：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 404, 188, 416 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 402, 189, 419 ], "spans": [ { "bbox": [ 88, 402, 189, 419 ], "type": "text", "content": "cd /home/shiyanlou", "score": 1.0 } ] } ] }, { "bbox": [ 87, 432, 155, 443 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 431, 155, 444 ], "spans": [ { "bbox": [ 88, 431, 155, 444 ], "type": "text", "content": "source .zshrc", "score": 1.0 } ] } ] }, { "bbox": [ 86, 486, 426, 499 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 486, 429, 501 ], "spans": [ { "bbox": [ 88, 486, 429, 501 ], "type": "text", "content": "source 命令还有一个别名就是 .，上面的命令如果替换成 . 的方式就该是：", "score": 1.0 } ] } ] }, { "bbox": [ 88, 514, 131, 525 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 513, 133, 528 ], "spans": [ { "bbox": [ 88, 513, 133, 528 ], "type": "text", "content": ". ./.zshrc", "score": 1.0 } ] } ] }, { "bbox": [ 86, 541, 359, 554 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 89, 542, 359, 556 ], "spans": [ { "bbox": [ 89, 542, 359, 556 ], "type": "text", "content": "在使用.的时候，需要注意与表示当前路径的那个点区分开。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 569, 502, 597 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 570, 502, 582 ], "spans": [ { "bbox": [ 89, 570, 502, 582 ], "type": "text", "content": "注意第一个点后面有一个空格，而且后面的文件必须指定完整的绝对或相对路径名", "score": 1.0 } ] }, { "bbox": [ 88, 584, 173, 599 ], "spans": [ { "bbox": [ 88, 584, 173, 599 ], "type": "text", "content": "source 则不需要。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 613, 111, 624 ], "type": "title", "angle": 0, "index": 12, "lines": [ { "bbox": [ 88, 611, 113, 629 ], "spans": [ { "bbox": [ 88, 611, 113, 629 ], "type": "text", "content": "总结", "score": 1.0 } ] } ] }, { "bbox": [ 104, 640, 329, 680 ], "type": "list", "angle": 0, "index": 15, "blocks": [ { "bbox": [ 104, 640, 312, 652 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 106, 640, 312, 654 ], "spans": [ { "bbox": [ 106, 640, 312, 654 ], "type": "text", "content": " 加./：显式执行当前目录下的脚本/程序。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 667, 329, 680 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 105, 667, 330, 682 ], "spans": [ { "bbox": [ 105, 667, 330, 682 ], "type": "text", "content": " 不加 ./：要求命令位于 PATH 包含的目录中。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 695, 397, 708 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 89, 695, 396, 709 ], "spans": [ { "bbox": [ 89, 695, 308, 709 ], "type": "text", "content": "位置变量用于接收从命令行传递到脚本的参数：", "score": 1.0 }, { "bbox": [ 308, 695, 323, 708 ], "type": "inline_equation", "content": "\\$ 0", "score": 0.76 }, { "bbox": [ 323, 695, 330, 709 ], "type": "text", "content": "，", "score": 1.0 }, { "bbox": [ 330, 695, 345, 708 ], "type": "inline_equation", "content": "\\$ 1", "score": 0.71 }, { "bbox": [ 345, 695, 353, 709 ], "type": "text", "content": "，", "score": 1.0 }, { "bbox": [ 353, 695, 368, 708 ], "type": "inline_equation", "content": "\\$ 2", "score": 0.76 }, { "bbox": [ 368, 695, 376, 709 ], "type": "text", "content": "，", "score": 1.0 }, { "bbox": [ 376, 695, 396, 708 ], "type": "inline_equation", "content": "\\$ 3\\ldots", "score": 0.62 } ] } ] }, { "bbox": [ 86, 723, 498, 751 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 723, 500, 736 ], "spans": [ { "bbox": [ 88, 723, 103, 735 ], "type": "inline_equation", "content": "\\$ 0", "score": 0.85 }, { "bbox": [ 103, 724, 232, 736 ], "type": "text", "content": "就是脚本文件自身的名字，", "score": 1.0 }, { "bbox": [ 232, 723, 246, 735 ], "type": "inline_equation", "content": "\\$ 1", "score": 0.84 }, { "bbox": [ 246, 724, 322, 736 ], "type": "text", "content": "是第一个参数，", "score": 1.0 }, { "bbox": [ 323, 723, 337, 735 ], "type": "inline_equation", "content": "\\$ 2", "score": 0.86 }, { "bbox": [ 337, 724, 412, 736 ], "type": "text", "content": "是第二个参数，", "score": 1.0 }, { "bbox": [ 412, 723, 427, 735 ], "type": "inline_equation", "content": "\\$ 3", "score": 0.83 }, { "bbox": [ 428, 724, 500, 736 ], "type": "text", "content": "是第三个参数，", "score": 1.0 } ] }, { "bbox": [ 88, 737, 500, 753 ], "spans": [ { "bbox": [ 88, 737, 166, 753 ], "type": "text", "content": "然后是第四个。", "score": 1.0 }, { "bbox": [ 166, 739, 182, 751 ], "type": "inline_equation", "content": "\\$ 9", "score": 0.84 }, { "bbox": [ 182, 737, 427, 753 ], "type": "text", "content": "之后的位置参数就必须用大括号括起来了，比如，", "score": 1.0 }, { "bbox": [ 427, 739, 456, 751 ], "type": "inline_equation", "content": "\\$ \\{10\\}", "score": 0.61 }, { "bbox": [ 456, 737, 500, 753 ], "type": "text", "content": "，${11}，", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 22 }, { "para_blocks": [ { "bbox": [ 88, 79, 120, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 87, 78, 122, 96 ], "spans": [ { "bbox": [ 87, 78, 122, 96 ], "type": "text", "content": "${12}。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 106, 154, 120 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 106, 154, 121 ], "spans": [ { "bbox": [ 89, 106, 154, 121 ], "type": "text", "content": "位置参数实例", "score": 1.0 } ] } ] }, { "bbox": [ 86, 134, 420, 147 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 134, 420, 148 ], "spans": [ { "bbox": [ 89, 134, 420, 148 ], "type": "text", "content": "在运行脚本的时候，有时候是需要参数的，这里我们学习如何获取参数。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 161, 504, 343 ], "type": "list", "angle": 0, "index": 9, "blocks": [ { "bbox": [ 104, 161, 260, 173 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 105, 162, 260, 174 ], "spans": [ { "bbox": [ 105, 162, 260, 174 ], "type": "text", "content": " $# ： 传递到脚本的参数个数", "score": 1.0 } ] } ] }, { "bbox": [ 104, 189, 504, 217 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 110, 189, 505, 202 ], "spans": [ { "bbox": [ 110, 189, 505, 202 ], "type": "text", "content": " $* ： 以一个单字符串显示所有向脚本传递的参数。与位置变量不同,此选项参数可", "score": 1.0 } ] }, { "bbox": [ 124, 204, 170, 218 ], "spans": [ { "bbox": [ 124, 204, 170, 218 ], "type": "text", "content": "超过 9 个", "score": 1.0 } ] } ] }, { "bbox": [ 104, 232, 274, 244 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 105, 232, 275, 246 ], "spans": [ { "bbox": [ 105, 232, 275, 246 ], "type": "text", "content": " $$ ： 脚本运行的当前进程 ID 号", "score": 1.0 } ] } ] }, { "bbox": [ 104, 260, 324, 272 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 105, 260, 325, 275 ], "spans": [ { "bbox": [ 105, 260, 325, 275 ], "type": "text", "content": " $! ： 后台运行的最后一个进程的进程 ID 号", "score": 1.0 } ] } ] }, { "bbox": [ 104, 287, 418, 300 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 105, 287, 419, 301 ], "spans": [ { "bbox": [ 105, 287, 167, 301 ], "type": "text", "content": " $@ ： 与", "score": 1.0 }, { "bbox": [ 167, 287, 182, 300 ], "type": "inline_equation", "content": "\\$ ^ { \\star }", "score": 0.73 }, { "bbox": [ 183, 287, 419, 301 ], "type": "text", "content": "相同,但是使用时加引号，并在引号中返回每个参数", "score": 1.0 } ] } ] }, { "bbox": [ 104, 315, 504, 343 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 107, 315, 506, 328 ], "spans": [ { "bbox": [ 107, 315, 123, 328 ], "type": "text", "content": "", "score": 1.0 }, { "bbox": [ 124, 315, 138, 327 ], "type": "inline_equation", "content": "\\$ 7", "score": 0.73 }, { "bbox": [ 138, 315, 506, 328 ], "type": "text", "content": "： 显示最后命令的退出状态。 0 表示没有错误，其他任何值（如 1）表明有错", "score": 1.0 } ] }, { "bbox": [ 123, 329, 143, 346 ], "spans": [ { "bbox": [ 123, 329, 143, 346 ], "type": "text", "content": "误。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 105, 358, 171, 370 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 107, 358, 172, 372 ], "spans": [ { "bbox": [ 107, 358, 172, 372 ], "type": "text", "content": "用户工作环境", "score": 1.0 } ] } ] }, { "bbox": [ 104, 386, 504, 414 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 107, 386, 504, 399 ], "spans": [ { "bbox": [ 107, 386, 504, 399 ], "type": "text", "content": "用户登录系统时，Shell为用户自动定义唯一的工作环境并对该环境进行维护直至用户", "score": 1.0 } ] }, { "bbox": [ 105, 400, 499, 417 ], "spans": [ { "bbox": [ 105, 400, 121, 417 ], "type": "text", "content": "注", "score": 1.0 }, { "bbox": [ 298, 400, 314, 416 ], "type": "text", "content": "销", "score": 1.0 }, { "bbox": [ 492, 407, 499, 416 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 417, 503, 444 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 106, 416, 504, 431 ], "spans": [ { "bbox": [ 106, 416, 504, 431 ], "type": "text", "content": "该环境将定义如身份、工作场所和正在运行的进程等特性。这些特性由指定的环境变", "score": 1.0 } ] }, { "bbox": [ 106, 431, 428, 447 ], "spans": [ { "bbox": [ 106, 431, 120, 446 ], "type": "text", "content": "量", "score": 1.0 }, { "bbox": [ 185, 432, 199, 446 ], "type": "text", "content": "值", "score": 1.0 }, { "bbox": [ 263, 431, 279, 447 ], "type": "text", "content": "定", "score": 1.0 }, { "bbox": [ 342, 431, 357, 447 ], "type": "text", "content": "义", "score": 1.0 }, { "bbox": [ 421, 438, 428, 446 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 448, 504, 491 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 105, 448, 499, 461 ], "spans": [ { "bbox": [ 105, 448, 499, 461 ], "type": "text", "content": "用 户 工 作 环 境 有 登 录 环 境 和 非 登 录 环 境 之 分 。", "score": 1.0 } ] }, { "bbox": [ 107, 463, 499, 477 ], "spans": [ { "bbox": [ 107, 463, 499, 477 ], "type": "text", "content": "登录环境是指用户登录系统时的工作环境，此时的 Shell对登录用户而言是主Shell。", "score": 1.0 } ] }, { "bbox": [ 107, 479, 493, 493 ], "spans": [ { "bbox": [ 107, 479, 493, 493 ], "type": "text", "content": "非 登 录 环 境 是 指 用 户 再 调 用 子 Shell 时 所 使 用 的 用 户 环 境 。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 494, 504, 538 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 103, 491, 508, 511 ], "spans": [ { "bbox": [ 103, 491, 123, 511 ], "type": "text", "content": "对", "score": 1.0 }, { "bbox": [ 152, 492, 170, 510 ], "type": "text", "content": "所", "score": 1.0 }, { "bbox": [ 201, 492, 218, 511 ], "type": "text", "content": "有", "score": 1.0 }, { "bbox": [ 249, 493, 265, 510 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 296, 493, 313, 510 ], "type": "text", "content": "户", "score": 1.0 }, { "bbox": [ 346, 492, 363, 510 ], "type": "text", "content": "进", "score": 1.0 }, { "bbox": [ 394, 492, 411, 510 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 443, 491, 459, 510 ], "type": "text", "content": "设", "score": 1.0 }, { "bbox": [ 491, 493, 508, 510 ], "type": "text", "content": "置", "score": 1.0 } ] }, { "bbox": [ 104, 507, 166, 526 ], "spans": [ { "bbox": [ 104, 507, 166, 526 ], "type": "text", "content": "/etc/profile", "score": 1.0 } ] }, { "bbox": [ 104, 523, 167, 542 ], "spans": [ { "bbox": [ 104, 523, 167, 542 ], "type": "text", "content": "/etc/bashrc", "score": 1.0 } ] } ] }, { "bbox": [ 104, 556, 504, 570 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 105, 555, 506, 573 ], "spans": [ { "bbox": [ 105, 556, 121, 573 ], "type": "text", "content": "只", "score": 1.0 }, { "bbox": [ 147, 556, 164, 573 ], "type": "text", "content": "对", "score": 1.0 }, { "bbox": [ 192, 556, 205, 572 ], "type": "text", "content": "当", "score": 1.0 }, { "bbox": [ 234, 556, 249, 572 ], "type": "text", "content": "前", "score": 1.0 }, { "bbox": [ 276, 556, 292, 572 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 318, 556, 336, 572 ], "type": "text", "content": "户", "score": 1.0 }, { "bbox": [ 362, 556, 379, 572 ], "type": "text", "content": "进", "score": 1.0 }, { "bbox": [ 405, 556, 421, 572 ], "type": "text", "content": "行", "score": 1.0 }, { "bbox": [ 449, 556, 465, 572 ], "type": "text", "content": "设", "score": 1.0 }, { "bbox": [ 491, 555, 506, 572 ], "type": "text", "content": "置", "score": 1.0 } ] } ] }, { "bbox": [ 104, 573, 181, 585 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 107, 572, 183, 587 ], "spans": [ { "bbox": [ 107, 572, 183, 587 ], "type": "text", "content": "~/.bash_profile", "score": 1.0 } ] } ] }, { "bbox": [ 104, 589, 154, 600 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 106, 587, 157, 602 ], "spans": [ { "bbox": [ 106, 587, 157, 602 ], "type": "text", "content": "~/.bashrc", "score": 1.0 } ] } ] }, { "bbox": [ 104, 603, 504, 632 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 105, 602, 506, 618 ], "spans": [ { "bbox": [ 105, 602, 506, 618 ], "type": "text", "content": "通 常 ， 个 人 bash 环 境 设 置 都 定 义 在 ~/.bashrc 文 件 里", "score": 1.0 } ] }, { "bbox": [ 107, 619, 279, 633 ], "spans": [ { "bbox": [ 107, 619, 279, 633 ], "type": "text", "content": "登录shell和非登录shell的启动过程", "score": 1.0 } ] } ] }, { "bbox": [ 104, 647, 504, 660 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 104, 645, 508, 665 ], "spans": [ { "bbox": [ 104, 645, 138, 665 ], "type": "text", "content": "Login", "score": 1.0 }, { "bbox": [ 478, 645, 508, 662 ], "type": "text", "content": "shell", "score": 1.0 } ] } ] }, { "bbox": [ 104, 663, 504, 675 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 105, 661, 506, 677 ], "spans": [ { "bbox": [ 105, 661, 164, 677 ], "type": "text", "content": "/etc/profile", "score": 1.0 }, { "bbox": [ 285, 662, 295, 677 ], "type": "text", "content": "", "score": 1.0 }, { "bbox": [ 414, 661, 506, 677 ], "type": "text", "content": "/etc/profile.d/*.sh", "score": 1.0 } ] } ] }, { "bbox": [ 105, 693, 212, 706 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 106, 693, 213, 708 ], "spans": [ { "bbox": [ 106, 693, 213, 708 ], "type": "text", "content": "$HOME/.bash_profile", "score": 1.0 } ] } ] }, { "bbox": [ 105, 725, 185, 736 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 105, 725, 186, 739 ], "spans": [ { "bbox": [ 105, 725, 186, 739 ], "type": "text", "content": "$HOME/.bashrc", "score": 1.0 } ] } ] }, { "bbox": [ 312, 725, 320, 735 ], "type": "text", "angle": 0, "index": 23, "lines": [ { "bbox": [ 313, 726, 321, 738 ], "spans": [ { "bbox": [ 313, 726, 321, 738 ], "type": "text", "content": "", "score": 1.0 } ] } ] }, { "bbox": [ 447, 725, 505, 736 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 447, 724, 507, 739 ], "spans": [ { "bbox": [ 447, 724, 507, 739 ], "type": "text", "content": "/etc/bashrc", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 23 }, { "para_blocks": [ { "bbox": [ 104, 153, 509, 432 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 107, 153, 509, 165 ], "spans": [ { "bbox": [ 107, 153, 509, 165 ], "type": "text", "content": "通常用户在 bash 下输入命令时不必把命令输全， shell 就能判断出你所要输入的命令。", "score": 1.0 } ] }, { "bbox": [ 107, 169, 505, 180 ], "spans": [ { "bbox": [ 107, 169, 505, 180 ], "type": "text", "content": "该功能的核心思想是：bash 根据用户已输入的信息来查找以这些信息开头的命令，从", "score": 1.0 } ] }, { "bbox": [ 107, 185, 505, 197 ], "spans": [ { "bbox": [ 107, 185, 505, 197 ], "type": "text", "content": "而试图完成当前命令的输入工作。用来执行这项功能的键是 Tab 键，按下一次 Tab 键", "score": 1.0 } ] }, { "bbox": [ 107, 200, 506, 213 ], "spans": [ { "bbox": [ 107, 200, 506, 213 ], "type": "text", "content": "后，bash 就试图完成整个命令的输入，如果不成功，可以再按一次 Tab 键，这时", "score": 1.0 } ] }, { "bbox": [ 107, 215, 500, 228 ], "spans": [ { "bbox": [ 107, 215, 500, 228 ], "type": "text", "content": "bash 将 列 出 所 有 能 够 与 当 前 输 入 字 符 相 匹 配 的 命 令 列 表 。", "score": 1.0 } ] }, { "bbox": [ 107, 231, 509, 244 ], "spans": [ { "bbox": [ 107, 231, 509, 244 ], "type": "text", "content": "通常用户在 bash 下输入命令时不必把命令输全， shell 就能判断出你所要输入的命令。", "score": 1.0 } ] }, { "bbox": [ 106, 245, 506, 260 ], "spans": [ { "bbox": [ 106, 245, 506, 260 ], "type": "text", "content": "该功能的核心思想是：bash 根据用户已输入的信息来查找以这些信息开头的命令，从", "score": 1.0 } ] }, { "bbox": [ 107, 262, 505, 275 ], "spans": [ { "bbox": [ 107, 262, 505, 275 ], "type": "text", "content": "而试图完成当前命令的输入工作。用来执行这项功能的键是 Tab 键，按下一次 Tab 键", "score": 1.0 } ] }, { "bbox": [ 107, 278, 506, 291 ], "spans": [ { "bbox": [ 107, 278, 506, 291 ], "type": "text", "content": "后，bash 就试图完成整个命令的输入，如果不成功，可以再按一次 Tab 键，这时", "score": 1.0 } ] }, { "bbox": [ 106, 293, 502, 306 ], "spans": [ { "bbox": [ 106, 293, 502, 306 ], "type": "text", "content": "bash 将 列 出 所 有 能 够 与 当 前 输 入 字 符 相 匹 配 的 命 令 列 表 。", "score": 1.0 } ] }, { "bbox": [ 105, 308, 507, 323 ], "spans": [ { "bbox": [ 105, 309, 120, 322 ], "type": "text", "content": "键", "score": 1.0 }, { "bbox": [ 201, 308, 218, 322 ], "type": "text", "content": "盘", "score": 1.0 }, { "bbox": [ 298, 308, 314, 323 ], "type": "text", "content": "快", "score": 1.0 }, { "bbox": [ 394, 308, 411, 323 ], "type": "text", "content": "捷", "score": 1.0 }, { "bbox": [ 491, 308, 507, 323 ], "type": "text", "content": "键", "score": 1.0 } ] }, { "bbox": [ 105, 323, 506, 339 ], "spans": [ { "bbox": [ 105, 323, 506, 339 ], "type": "text", "content": "最 简 单 的 方 法 是 用 上 下 方 向 键 、 和 键 来 查 看 历 史 命 令", "score": 1.0 } ] }, { "bbox": [ 106, 340, 505, 353 ], "spans": [ { "bbox": [ 106, 340, 505, 353 ], "type": "text", "content": "如果需要的话，可以使用键盘上的编辑功能键对显示在命令行上的命令进行编辑", "score": 1.0 } ] }, { "bbox": [ 105, 354, 506, 370 ], "spans": [ { "bbox": [ 105, 354, 121, 370 ], "type": "text", "content": "感", "score": 1.0 }, { "bbox": [ 182, 355, 199, 370 ], "type": "text", "content": "叹", "score": 1.0 }, { "bbox": [ 260, 354, 275, 370 ], "type": "text", "content": "号", "score": 1.0 }, { "bbox": [ 336, 355, 354, 370 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 413, 355, 430, 370 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 491, 356, 506, 370 ], "type": "text", "content": "法", "score": 1.0 } ] }, { "bbox": [ 105, 370, 508, 386 ], "spans": [ { "bbox": [ 105, 370, 120, 386 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 159, 372, 171, 385 ], "type": "text", "content": "!!", "score": 1.0 }, { "bbox": [ 208, 370, 508, 386 ], "type": "text", "content": "执 行 最 近 执 行 过 的 命 令", "score": 1.0 } ] }, { "bbox": [ 105, 386, 506, 401 ], "spans": [ { "bbox": [ 105, 386, 120, 401 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 130, 386, 274, 401 ], "type": "text", "content": "! < 命 令 事 件 号", "score": 1.0 }, { "bbox": [ 274, 388, 285, 398 ], "type": "inline_equation", "content": ">", "score": 0.6 }, { "bbox": [ 285, 386, 506, 401 ], "type": "text", "content": "执 行 已 经 运 行 过 的 命 令", "score": 1.0 } ] }, { "bbox": [ 106, 402, 505, 416 ], "spans": [ { "bbox": [ 106, 402, 270, 416 ], "type": "text", "content": "用 ! <已经使用过的命令前面的部分", "score": 1.0 }, { "bbox": [ 270, 403, 279, 414 ], "type": "inline_equation", "content": ">", "score": 0.61 }, { "bbox": [ 279, 402, 505, 416 ], "type": "text", "content": "执行已经运行过的以该字符串开头的最近的命令", "score": 1.0 } ] }, { "bbox": [ 105, 417, 151, 433 ], "spans": [ { "bbox": [ 105, 417, 151, 433 ], "type": "text", "content": "命令别名", "score": 1.0 } ] } ] }, { "type": "code", "bbox": [ 104, 444, 506, 631 ], "blocks": [ { "bbox": [ 104, 444, 506, 631 ], "lines": [ { "bbox": [ 104, 444, 506, 631 ], "spans": [ { "bbox": [ 104, 444, 506, 631 ], "type": "text", "content": "允许用户按照自己喜欢的方式对命令进行自定义格式 \nalias [alias_name='original_command']说明 \nalias_name 是用户给命令取的别名。original_command是原来的命令和参数。若命令中包含空格或其他的特殊字符串必须使用引号。在定义别名时，等号两边不允许有空格。不带任何参数的alias命令显示当前已定义的所有别名。可以使用unalias alias_name命令取消某个别名的定义。如果用户需要别名的定义在每次登录时均有效，应该将其写入用户自家目录下的.bashrc 文件 中" } ] } ], "index": 7, "angle": 0, "type": "code_body" } ], "index": 7, "sub_type": "code", "guess_lang": "txt" }, { "type": "code", "bbox": [ 104, 647, 508, 709 ], "blocks": [ { "bbox": [ 104, 647, 508, 709 ], "lines": [ { "bbox": [ 104, 647, 508, 709 ], "spans": [ { "bbox": [ 104, 647, 508, 709 ], "type": "text", "content": "定义 别 名 举 例 \nalias Ih='ls -lh' \nalias grep='grep --color=auto' \nalias gitcam='git commit -a -m'" } ] } ], "index": 8, "angle": 0, "type": "code_body" } ], "index": 8, "sub_type": "code", "guess_lang": "shell" }, { "bbox": [ 105, 711, 506, 756 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 105, 710, 508, 724 ], "spans": [ { "bbox": [ 105, 710, 121, 724 ], "type": "text", "content": "注", "score": 1.0 }, { "bbox": [ 492, 710, 508, 724 ], "type": "text", "content": "意", "score": 1.0 } ] }, { "bbox": [ 106, 726, 506, 740 ], "spans": [ { "bbox": [ 106, 726, 506, 740 ], "type": "text", "content": "若系统中有一个命令，同时又定义了一个与之同名的别名（例如，系统中有 grep命令，", "score": 1.0 } ] }, { "bbox": [ 105, 742, 500, 756 ], "spans": [ { "bbox": [ 105, 742, 500, 756 ], "type": "text", "content": "且又 定义了 grep 的 别 名 ） ，则别 名 将优先 于 系 统 中原有 的 命 令 的 执 行 。", "score": 1.0 } ] } ] } ], "discarded_blocks": [ { "bbox": [ 105, 95, 161, 107 ], "type": "header", "angle": 0, "index": 0, "lines": [ { "bbox": [ 105, 93, 161, 111 ], "spans": [ { "bbox": [ 105, 93, 161, 111 ], "type": "text", "content": "Non-Login", "score": 1.0 } ] } ] }, { "bbox": [ 105, 110, 186, 121 ], "type": "header", "angle": 0, "index": 1, "lines": [ { "bbox": [ 105, 110, 186, 124 ], "spans": [ { "bbox": [ 105, 110, 186, 124 ], "type": "text", "content": "$HOME/.bashrc", "score": 1.0 } ] } ] }, { "bbox": [ 105, 126, 151, 138 ], "type": "header", "angle": 0, "index": 2, "lines": [ { "bbox": [ 105, 124, 152, 141 ], "spans": [ { "bbox": [ 105, 124, 152, 141 ], "type": "text", "content": "命令补全", "score": 1.0 } ] } ] }, { "bbox": [ 480, 95, 506, 106 ], "type": "header", "angle": 0, "index": 3, "lines": [ { "bbox": [ 479, 93, 508, 109 ], "spans": [ { "bbox": [ 479, 93, 508, 109 ], "type": "text", "content": "shell", "score": 1.0 } ] } ] }, { "bbox": [ 312, 111, 321, 121 ], "type": "header", "angle": 0, "index": 4, "lines": [ { "bbox": [ 313, 111, 321, 123 ], "spans": [ { "bbox": [ 313, 111, 321, 123 ], "type": "text", "content": "", "score": 1.0 } ] } ] }, { "bbox": [ 448, 111, 506, 122 ], "type": "header", "angle": 0, "index": 5, "lines": [ { "bbox": [ 447, 109, 506, 124 ], "spans": [ { "bbox": [ 447, 109, 506, 124 ], "type": "text", "content": "/etc/bashrc", "score": 1.0 } ] } ] } ], "page_size": [ 595, 841 ], "page_idx": 24 }, { "para_blocks": [ { "bbox": [ 105, 79, 506, 110 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 105, 78, 506, 93 ], "spans": [ { "bbox": [ 105, 78, 506, 93 ], "type": "text", "content": "要想临时使用系统中的命令而非别名，应该在命令前添加“\\”字符，例如，$ \\grep 命", "score": 1.0 } ] }, { "bbox": [ 106, 94, 462, 109 ], "spans": [ { "bbox": [ 106, 94, 462, 109 ], "type": "text", "content": "令将运行系统中原来的 grep 命令而不是 grep 别名，它不在输出中显示颜色。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 128, 123, 147 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 85, 126, 124, 149 ], "spans": [ { "bbox": [ 85, 126, 124, 149 ], "type": "text", "content": "运算", "score": 1.0 } ] } ] }, { "bbox": [ 86, 199, 505, 290 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 88, 198, 508, 215 ], "spans": [ { "bbox": [ 88, 199, 117, 213 ], "type": "text", "content": "Bash", "score": 1.0 }, { "bbox": [ 157, 198, 508, 215 ], "type": "text", "content": "变 量 没 有 严 格 的 类 型 定 义", "score": 1.0 } ] }, { "bbox": [ 86, 213, 508, 230 ], "spans": [ { "bbox": [ 86, 213, 173, 230 ], "type": "text", "content": "本 质 上", "score": 1.0 }, { "bbox": [ 213, 215, 245, 228 ], "type": "text", "content": "Bash", "score": 1.0 }, { "bbox": [ 281, 213, 508, 230 ], "type": "text", "content": "变 量 都 是 字 符 串", "score": 1.0 } ] }, { "bbox": [ 88, 230, 505, 244 ], "spans": [ { "bbox": [ 88, 230, 505, 244 ], "type": "text", "content": "若一个字面常量或变量的值是纯数字的，不包含字母或其他字符， Bash可以将其视为长", "score": 1.0 } ] }, { "bbox": [ 88, 245, 505, 260 ], "spans": [ { "bbox": [ 88, 245, 505, 260 ], "type": "text", "content": "整 型 值 ， 并 可 做 算 数 运 算 和 比 较 运 算 。", "score": 1.0 } ] }, { "bbox": [ 86, 260, 508, 277 ], "spans": [ { "bbox": [ 86, 261, 116, 275 ], "type": "text", "content": "Bash", "score": 1.0 }, { "bbox": [ 150, 260, 508, 277 ], "type": "text", "content": "也 允 许 显 式 地 声 明 整 型 变 量", "score": 1.0 } ] }, { "bbox": [ 86, 275, 506, 293 ], "spans": [ { "bbox": [ 86, 275, 129, 293 ], "type": "text", "content": "declare", "score": 1.0 }, { "bbox": [ 192, 278, 206, 291 ], "type": "text", "content": "-i", "score": 1.0 }, { "bbox": [ 336, 277, 351, 291 ], "type": "text", "content": "变", "score": 1.0 }, { "bbox": [ 415, 277, 428, 291 ], "type": "text", "content": "量", "score": 1.0 }, { "bbox": [ 492, 277, 506, 291 ], "type": "text", "content": "名", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 103, 290, 421, 438 ], "blocks": [ { "bbox": [ 103, 290, 421, 438 ], "lines": [ { "bbox": [ 103, 290, 421, 438 ], "spans": [ { "bbox": [ 103, 290, 421, 438 ], "type": "table", "html": "
+、-、*、/ (四则运算)
**、% (幂运算和模运算,取余数)
<<、>> (按位左移和按位右移)
&、^、| (按位与、按位异或和按位或)
=、+=、-=、*=、/=、%=><<=、>==、&=、^=、|= (赋值运算)
<、>、<=、>=、==、!= (比较操作符)
&&、|| (逻辑与和逻辑或)
", "image_path": "081c888b50dca276f3f54733ce43d6383c374f344a628b63bdb0a795ca40c019.jpg" } ] } ], "index": 3, "angle": 0, "type": "table_body" } ], "index": 3 }, { "bbox": [ 106, 453, 348, 470 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 104, 451, 350, 471 ], "spans": [ { "bbox": [ 104, 451, 350, 471 ], "type": "text", "content": "注：按位运算是以二进制形式进行的。", "score": 0.998 } ] } ] }, { "bbox": [ 86, 507, 510, 553 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 508, 509, 520 ], "spans": [ { "bbox": [ 89, 508, 509, 520 ], "type": "text", "content": "Bash本身没有计算功能，需要借助其他命令完成表达式的运算，包括算术运算和逻辑运算。", "score": 1.0 } ] }, { "bbox": [ 89, 523, 511, 536 ], "spans": [ { "bbox": [ 89, 523, 511, 536 ], "type": "text", "content": "在表达式中使用了各种运算符，具体于使用的命令有关，参看相关命令的 man帮助手册。", "score": 1.0 } ] }, { "bbox": [ 89, 539, 487, 554 ], "spans": [ { "bbox": [ 89, 539, 487, 554 ], "type": "text", "content": "expr 命令可以进行一些算术运算，包括加、减、乘、除等。也可以进行一些逻辑运算。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 566, 415, 661 ], "type": "list", "angle": 0, "index": 10, "blocks": [ { "bbox": [ 104, 566, 415, 579 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 122, 566, 414, 580 ], "spans": [ { "bbox": [ 122, 566, 414, 580 ], "type": "text", "content": "计算结果赋值给变量时，要注意使用反撇号（与~ 在同一个键）", "score": 1.0 } ] } ] }, { "bbox": [ 104, 594, 392, 607 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 123, 594, 392, 608 ], "spans": [ { "bbox": [ 123, 594, 273, 608 ], "type": "text", "content": "表达式和运算符之间要有空格，", "score": 1.0 }, { "bbox": [ 273, 594, 311, 607 ], "type": "inline_equation", "content": "\\$ 0+\\$ 6", "score": 0.91 }, { "bbox": [ 312, 594, 335, 608 ], "type": "text", "content": "写成", "score": 1.0 }, { "bbox": [ 336, 594, 368, 607 ], "type": "inline_equation", "content": "\\$ 0+\\$ 6", "score": 0.88 }, { "bbox": [ 368, 594, 392, 608 ], "type": "text", "content": "不行", "score": 1.0 } ] } ] }, { "bbox": [ 104, 621, 356, 634 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 122, 622, 355, 635 ], "spans": [ { "bbox": [ 122, 622, 355, 635 ], "type": "text", "content": "乘号（*）前边必须加反斜杠（)才能实现乘法运算", "score": 1.0 } ] } ] }, { "bbox": [ 105, 649, 211, 661 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 124, 650, 211, 662 ], "spans": [ { "bbox": [ 124, 650, 211, 662 ], "type": "text", "content": "除法是取整的除法", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 677, 504, 705 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 677, 504, 689 ], "spans": [ { "bbox": [ 89, 677, 504, 689 ], "type": "text", "content": "Echo中单引号的原则是不管里面的内容是什么都原样输出，不能识别通配符、变量、命令", "score": 1.0 } ] }, { "bbox": [ 88, 689, 108, 709 ], "spans": [ { "bbox": [ 88, 689, 108, 709 ], "type": "text", "content": "等。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 719, 505, 749 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 89, 720, 505, 733 ], "spans": [ { "bbox": [ 89, 720, 505, 733 ], "type": "text", "content": "双引号就比单引号人性化一点，可以识别变量和特殊转义符，进行一步翻译再输出，同时", "score": 1.0 } ] }, { "bbox": [ 89, 735, 505, 748 ], "spans": [ { "bbox": [ 89, 735, 339, 748 ], "type": "text", "content": "我这里再强调一下在shell脚本中使用双引号必须结合", "score": 1.0 }, { "bbox": [ 339, 736, 347, 748 ], "type": "inline_equation", "content": "\\$ 5", "score": 0.73 }, { "bbox": [ 348, 735, 505, 748 ], "type": "text", "content": "、/和`这三个来申明变量、引入特", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 25 }, { "para_blocks": [ { "bbox": [ 86, 79, 336, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 89, 79, 336, 94 ], "spans": [ { "bbox": [ 89, 79, 336, 94 ], "type": "text", "content": "色符号和加如命令，这样才可以直接被编译器识别的。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 106, 138, 120 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 106, 139, 120 ], "spans": [ { "bbox": [ 88, 106, 139, 120 ], "type": "text", "content": "逻辑运算：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 134, 505, 163 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 95, 133, 505, 148 ], "spans": [ { "bbox": [ 95, 133, 505, 148 ], "type": "text", "content": "（但这里要注意逻辑运算的话，&和|与一般的逻辑运算||和&&不同吧！不要将这两个搞", "score": 1.0 } ] }, { "bbox": [ 86, 148, 107, 165 ], "spans": [ { "bbox": [ 86, 148, 107, 165 ], "type": "text", "content": "混）", "score": 1.0 } ] } ] }, { "bbox": [ 86, 177, 510, 191 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 175, 511, 192 ], "spans": [ { "bbox": [ 88, 175, 511, 192 ], "type": "text", "content": "在 expr 命令中，| 不是逻辑或，而是一个 模式匹配（Alternation）运算符，其行为如下：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 205, 153, 218 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 107, 205, 154, 218 ], "spans": [ { "bbox": [ 107, 210, 112, 214 ], "type": "text", "content": ".", "score": 0.804 }, { "bbox": [ 123, 205, 154, 218 ], "type": "text", "content": "规则：", "score": 1.0 } ] } ] }, { "bbox": [ 141, 232, 324, 273 ], "type": "list", "angle": 0, "index": 7, "blocks": [ { "bbox": [ 141, 232, 324, 246 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 141, 231, 326, 248 ], "spans": [ { "bbox": [ 141, 231, 257, 248 ], "type": "text", "content": "o 若 ARG1 非空且非零", "score": 1.0 }, { "bbox": [ 272, 231, 326, 248 ], "type": "text", "content": "返回 ARG1", "score": 1.0 } ] } ] }, { "bbox": [ 141, 260, 251, 273 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 141, 259, 251, 275 ], "spans": [ { "bbox": [ 141, 259, 183, 275 ], "type": "text", "content": "o 否则", "score": 1.0 }, { "bbox": [ 197, 259, 251, 275 ], "type": "text", "content": "返回 ARG2", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 104, 287, 414, 301 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 122, 285, 415, 302 ], "spans": [ { "bbox": [ 122, 285, 415, 302 ], "type": "text", "content": "返回值：直接返回 ARG1 或 ARG2 的原始值，不是布尔值 1/0。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 315, 189, 329 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 87, 314, 188, 330 ], "spans": [ { "bbox": [ 87, 314, 188, 330 ], "type": "text", "content": ". expr 中的 & 运算符", "score": 1.0 } ] } ] }, { "bbox": [ 86, 343, 414, 356 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 86, 341, 417, 358 ], "spans": [ { "bbox": [ 86, 341, 417, 358 ], "type": "text", "content": "在 expr 中，& 是 “匹配”运算符（Match Operator），其行为如下：", "score": 1.0 } ] } ] }, { "bbox": [ 104, 370, 152, 383 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 107, 370, 153, 384 ], "spans": [ { "bbox": [ 107, 375, 112, 380 ], "type": "text", "content": ".", "score": 0.89 }, { "bbox": [ 123, 370, 153, 384 ], "type": "text", "content": "规则：", "score": 1.0 } ] } ] }, { "bbox": [ 141, 397, 380, 438 ], "type": "list", "angle": 0, "index": 14, "blocks": [ { "bbox": [ 141, 397, 380, 411 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 141, 396, 381, 412 ], "spans": [ { "bbox": [ 141, 396, 314, 412 ], "type": "text", "content": "o 若 ARG1 和 ARG2 都 非空且非零", "score": 1.0 }, { "bbox": [ 329, 396, 381, 412 ], "type": "text", "content": "返回 ARG1", "score": 1.0 } ] } ] }, { "bbox": [ 141, 425, 228, 438 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 141, 424, 229, 440 ], "spans": [ { "bbox": [ 141, 424, 183, 440 ], "type": "text", "content": "o 否则", "score": 1.0 }, { "bbox": [ 197, 424, 229, 440 ], "type": "text", "content": "返回 0", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 104, 453, 304, 466 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 122, 453, 304, 467 ], "spans": [ { "bbox": [ 122, 453, 304, 467 ], "type": "text", "content": "返回值：ARG1 或 0，不是布尔值 1/0。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 481, 277, 493 ], "type": "title", "angle": 0, "index": 16, "lines": [ { "bbox": [ 89, 481, 277, 495 ], "spans": [ { "bbox": [ 89, 481, 277, 495 ], "type": "text", "content": "另外的大小比较为真时返回 1 否则返回 0", "score": 1.0 } ] } ] }, { "bbox": [ 86, 508, 154, 521 ], "type": "title", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 508, 154, 523 ], "spans": [ { "bbox": [ 88, 508, 154, 523 ], "type": "text", "content": "Zsh 中的问题", "score": 1.0 } ] } ] }, { "bbox": [ 86, 535, 510, 596 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 88, 535, 506, 550 ], "spans": [ { "bbox": [ 88, 535, 506, 550 ], "type": "text", "content": "在 Zsh 中，当您运行 ret=`\\expr length \"hello\"`，反引号将会被解析成一个命令并尝试执", "score": 1.0 } ] }, { "bbox": [ 88, 550, 509, 565 ], "spans": [ { "bbox": [ 88, 550, 509, 565 ], "type": "text", "content": "行 expr length \"hello\"。然而，Zsh 报告了 command not found: 5 的错误。这表明，", "score": 1.0 } ] }, { "bbox": [ 88, 567, 506, 581 ], "spans": [ { "bbox": [ 88, 567, 506, 581 ], "type": "text", "content": "Zsh 在尝试解析输出结果时没有正确处理返回值。因为 expr length \"hello\"` 输出的是一个", "score": 1.0 } ] }, { "bbox": [ 88, 582, 353, 597 ], "spans": [ { "bbox": [ 88, 582, 353, 597 ], "type": "text", "content": "数字（5），Zsh 错误地将这个数字当作一个命令来执行。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 610, 160, 623 ], "type": "title", "angle": 0, "index": 19, "lines": [ { "bbox": [ 88, 608, 162, 625 ], "spans": [ { "bbox": [ 88, 608, 162, 625 ], "type": "text", "content": "Bash 中的行为", "score": 1.0 } ] } ] }, { "bbox": [ 86, 637, 505, 666 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 89, 639, 505, 650 ], "spans": [ { "bbox": [ 89, 639, 505, 650 ], "type": "text", "content": "Bash 在处理这个命令时表现得更宽容。Bash 会将反引号中的命令输出正确地捕获，并将", "score": 1.0 } ] }, { "bbox": [ 89, 654, 364, 666 ], "spans": [ { "bbox": [ 89, 654, 364, 666 ], "type": "text", "content": "结果（即5）赋值给ret 变量，而不会尝试将其解释为命令。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 681, 215, 694 ], "type": "title", "angle": 0, "index": 21, "lines": [ { "bbox": [ 88, 681, 215, 694 ], "spans": [ { "bbox": [ 88, 682, 143, 694 ], "type": "text", "content": "2. 反引号与", "score": 1.0 }, { "bbox": [ 143, 681, 160, 694 ], "type": "inline_equation", "content": "\\$ 0", "score": 0.63 }, { "bbox": [ 160, 682, 215, 694 ], "type": "text", "content": "语法的替代", "score": 1.0 } ] } ] }, { "bbox": [ 86, 708, 506, 753 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 89, 709, 504, 720 ], "spans": [ { "bbox": [ 89, 709, 504, 720 ], "type": "text", "content": "虽然反引号 ` 在大多数情况下能正常工作，但它并不总是最清晰和最可靠的选择。尤其是", "score": 1.0 } ] }, { "bbox": [ 89, 724, 506, 736 ], "spans": [ { "bbox": [ 89, 724, 506, 736 ], "type": "text", "content": "当命令返回数值或字符串时，反引号可能会带来意料之外的结果。现代 Shell（包括 Zsh", "score": 1.0 } ] }, { "bbox": [ 88, 740, 505, 752 ], "spans": [ { "bbox": [ 88, 740, 505, 752 ], "type": "text", "content": "和 Bash）更推荐使用 $() 代替反引号，因为它更容易嵌套和理解，并且更少出现解析错", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 26 }, { "para_blocks": [ { "bbox": [ 88, 79, 115, 91 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 86, 78, 118, 94 ], "spans": [ { "bbox": [ 86, 78, 118, 94 ], "type": "text", "content": "误。）", "score": 1.0 } ] } ] }, { "bbox": [ 88, 106, 202, 120 ], "type": "title", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 106, 202, 121 ], "spans": [ { "bbox": [ 89, 106, 202, 121 ], "type": "text", "content": "1. 为什么建议加双引号？", "score": 1.0 } ] } ] }, { "bbox": [ 86, 134, 285, 148 ], "type": "title", "angle": 0, "index": 2, "lines": [ { "bbox": [ 88, 134, 285, 148 ], "spans": [ { "bbox": [ 88, 134, 285, 148 ], "type": "text", "content": "(1) 防止变量值中的空格或特殊字符被解析", "score": 1.0 } ] } ] }, { "bbox": [ 104, 161, 504, 190 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 123, 160, 506, 175 ], "spans": [ { "bbox": [ 123, 160, 506, 175 ], "type": "text", "content": "如果 $PATH 中包含空格或特殊字符（如 *、?、$），不加引号时 Shell 会对其进", "score": 1.0 } ] }, { "bbox": [ 124, 178, 195, 190 ], "spans": [ { "bbox": [ 124, 178, 195, 190 ], "type": "text", "content": "行分词或扩展：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 205, 180, 218 ], "type": "title", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 205, 180, 218 ], "spans": [ { "bbox": [ 88, 205, 180, 218 ], "type": "text", "content": "(2) 避免通配符扩展", "score": 1.0 } ] } ] }, { "bbox": [ 104, 232, 448, 246 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 105, 232, 450, 246 ], "spans": [ { "bbox": [ 105, 232, 450, 246 ], "type": "text", "content": " 如果$PATH 包含* 或? 等通配符，不加引号时Shell 会尝试文件匹配：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 259, 190, 274 ], "type": "title", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 260, 190, 274 ], "spans": [ { "bbox": [ 88, 260, 190, 274 ], "type": "text", "content": "(3) 确保变量引用完整", "score": 1.0 } ] } ] }, { "bbox": [ 105, 287, 340, 301 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 123, 288, 342, 301 ], "spans": [ { "bbox": [ 123, 288, 342, 301 ], "type": "text", "content": "双引号能明确变量边界，避免与后续字符混淆：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 315, 436, 327 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 88, 316, 436, 328 ], "spans": [ { "bbox": [ 88, 316, 436, 328 ], "type": "text", "content": "# 不加引号时，若变量名后紧跟字母或下划线，会被误认为变量名的一部分", "score": 1.0 } ] } ] }, { "bbox": [ 86, 343, 233, 355 ], "type": "title", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 343, 234, 358 ], "spans": [ { "bbox": [ 88, 343, 234, 358 ], "type": "text", "content": "2. 什么情况下可以省略双引号？", "score": 1.0 } ] } ] }, { "bbox": [ 104, 370, 498, 398 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 124, 370, 499, 383 ], "spans": [ { "bbox": [ 124, 370, 499, 383 ], "type": "text", "content": "当变量值绝对不包含空格、通配符或特殊字符时（如纯字母数字和 : 的PATH），", "score": 1.0 } ] }, { "bbox": [ 125, 386, 195, 399 ], "spans": [ { "bbox": [ 125, 386, 195, 399 ], "type": "text", "content": "可以不加引号：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 413, 293, 426 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 88, 412, 294, 428 ], "spans": [ { "bbox": [ 88, 412, 209, 428 ], "type": "text", "content": "echo PATH=/usr/bin:/bin", "score": 1.0 }, { "bbox": [ 210, 415, 224, 425 ], "type": "inline_equation", "content": "> >", "score": 0.56 }, { "bbox": [ 225, 412, 294, 428 ], "type": "text", "content": ".zshrc # 安全", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 454, 454, 568 ], "blocks": [ { "bbox": [ 88, 454, 454, 568 ], "lines": [ { "bbox": [ 88, 454, 454, 568 ], "spans": [ { "bbox": [ 88, 454, 454, 568 ], "type": "table", "html": "
命令执行结果$?取值逻辑表达式值
成功01（真）
失败10（假）
", "image_path": "ea3b3937c9cdb5ff0fc91f1ce2bb8f29d12e736ddb11b854124dd1797f5f796b.jpg" } ] } ], "index": 12, "angle": 0, "type": "table_body" } ], "index": 12 }, { "bbox": [ 86, 581, 498, 610 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 88, 581, 500, 595 ], "spans": [ { "bbox": [ 88, 581, 500, 595 ], "type": "text", "content": "expr命令除了进行算术和逻辑运算之外（不是我想到&&与||，另外也并没有提到取非、", "score": 1.0 } ] }, { "bbox": [ 89, 597, 305, 610 ], "spans": [ { "bbox": [ 89, 597, 305, 610 ], "type": "text", "content": "异或、按位运算），还可以进行字符串的操作。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 652, 133, 664 ], "type": "title", "angle": 0, "index": 14, "lines": [ { "bbox": [ 88, 650, 135, 667 ], "spans": [ { "bbox": [ 88, 650, 135, 667 ], "type": "text", "content": "Test 命令", "score": 1.0 } ] } ] }, { "bbox": [ 86, 679, 498, 708 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 89, 680, 500, 693 ], "spans": [ { "bbox": [ 89, 680, 500, 693 ], "type": "text", "content": "Bash对于逻辑表达式的求值需要借助 test命令完成。。test命令中逻辑运算符有两套，", "score": 1.0 } ] }, { "bbox": [ 89, 696, 483, 708 ], "spans": [ { "bbox": [ 89, 696, 483, 708 ], "type": "text", "content": "分为数值型和字符型，另外还有对于文件进行判断的运算符，和表达式复合的运算符。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 723, 132, 735 ], "type": "title", "angle": 0, "index": 16, "lines": [ { "bbox": [ 88, 723, 134, 739 ], "spans": [ { "bbox": [ 88, 723, 134, 739 ], "type": "text", "content": "主要区别", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 27 }, { "para_blocks": [ { "type": "table", "bbox": [ 83, 96, 512, 441 ], "blocks": [ { "bbox": [ 83, 96, 512, 441 ], "lines": [ { "bbox": [ 83, 96, 512, 441 ], "spans": [ { "bbox": [ 83, 96, 512, 441 ], "type": "table", "html": "
特性test 10 -It 20 (或 [ 10 -It 20 ])expr 10 \\\\< 20
用途Shell 条件测试通用表达式计算
是 Shell 内置吗?☐是(高效)☐外部命令(较慢)
比较类型数值比较字符串比较(但数字仍可正确比较)
返回值(输出)返 回 0 (true) 或 1 (false)输出 1 (true) 或 0 (false),但 $?仍然是 0/1
符号-It (必须用 - 开头的运算符)< (必须转义为 \\< )
适用场景if 条件判断需要计算表达式并获取结果
", "image_path": "0c9d27fab33e67a0d4f144eefaf763bf5e9089acfc45c5be43defa6c2737f37a.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "bbox": [ 86, 454, 258, 467 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 454, 260, 469 ], "spans": [ { "bbox": [ 88, 454, 160, 469 ], "type": "text", "content": "test -n $f echo", "score": 1.0 }, { "bbox": [ 161, 455, 174, 467 ], "type": "inline_equation", "content": "\\$ 7", "score": 0.63 }, { "bbox": [ 174, 454, 260, 469 ], "type": "text", "content": "test -z $f echo $?", "score": 1.0 } ] } ] }, { "bbox": [ 86, 481, 175, 495 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 88, 481, 177, 496 ], "spans": [ { "bbox": [ 88, 481, 177, 496 ], "type": "text", "content": "结果都为0！奇怪。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 509, 504, 555 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 89, 511, 504, 522 ], "spans": [ { "bbox": [ 89, 511, 504, 522 ], "type": "text", "content": "bc是一个独立的bc是一个较为完整的工具，为Bash提供了更强的计算能力，提供了完备", "score": 1.0 } ] }, { "bbox": [ 89, 525, 503, 538 ], "spans": [ { "bbox": [ 89, 525, 503, 538 ], "type": "text", "content": "的类似C的编程语法的计算器，可以在交互式界面、文本或管道的方式方便的进行一些运", "score": 1.0 } ] }, { "bbox": [ 89, 541, 430, 554 ], "spans": [ { "bbox": [ 89, 541, 430, 554 ], "type": "text", "content": "算。支持多进制转换，任意精度调整，打印控制，函数支持，逻辑控制等。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 567, 505, 581 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 86, 565, 508, 585 ], "spans": [ { "bbox": [ 86, 567, 103, 585 ], "type": "text", "content": "算", "score": 1.0 }, { "bbox": [ 167, 566, 184, 585 ], "type": "text", "content": "术", "score": 1.0 }, { "bbox": [ 248, 567, 265, 585 ], "type": "text", "content": "运", "score": 1.0 }, { "bbox": [ 329, 567, 346, 585 ], "type": "text", "content": "算", "score": 1.0 }, { "bbox": [ 409, 565, 427, 585 ], "type": "text", "content": "扩", "score": 1.0 }, { "bbox": [ 491, 567, 508, 584 ], "type": "text", "content": "展", "score": 1.0 } ] } ] }, { "bbox": [ 88, 584, 157, 597 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 582, 158, 600 ], "spans": [ { "bbox": [ 88, 582, 158, 600 ], "type": "text", "content": "$[expression]", "score": 1.0 } ] } ] }, { "bbox": [ 88, 599, 162, 613 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 597, 164, 616 ], "spans": [ { "bbox": [ 88, 597, 164, 616 ], "type": "text", "content": "$((expression))", "score": 1.0 } ] } ] }, { "bbox": [ 86, 614, 498, 628 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 615, 500, 629 ], "spans": [ { "bbox": [ 88, 615, 141, 629 ], "type": "text", "content": "用 $[···] ，", "score": 1.0 }, { "bbox": [ 142, 615, 171, 629 ], "type": "inline_equation", "content": "\\$ (( \\cdots ) )", "score": 0.6 }, { "bbox": [ 172, 615, 427, 629 ], "type": "text", "content": "进 行整数 运 算时，括 号内变 量前 的美元符号", "score": 1.0 }, { "bbox": [ 427, 615, 438, 628 ], "type": "inline_equation", "content": "\\$ 1", "score": 0.68 }, { "bbox": [ 439, 615, 500, 629 ], "type": "text", "content": "可 以省 略。", "score": 1.0 } ] } ] }, { "bbox": [ 88, 630, 504, 645 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 86, 626, 506, 650 ], "spans": [ { "bbox": [ 86, 629, 128, 646 ], "type": "text", "content": "注 意", "score": 1.0 }, { "bbox": [ 150, 626, 370, 650 ], "type": "text", "content": "${···} ， $(···) ， $[···] ， $((···))", "score": 1.0 }, { "bbox": [ 390, 629, 506, 645 ], "type": "text", "content": "的 不 同 作 用", "score": 1.0 } ] } ] }, { "bbox": [ 87, 680, 154, 698 ], "type": "title", "angle": 0, "index": 9, "lines": [ { "bbox": [ 86, 679, 156, 702 ], "spans": [ { "bbox": [ 86, 679, 156, 702 ], "type": "text", "content": "双小括号", "score": 1.0 } ] } ] }, { "bbox": [ 86, 735, 450, 749 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 88, 736, 451, 751 ], "spans": [ { "bbox": [ 88, 736, 451, 751 ], "type": "text", "content": "双小括号中可以使用类似 C 语言的表达式，((exp))的格式更符合一般使用习惯。", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 28 }, { "para_blocks": [ { "bbox": [ 104, 79, 507, 238 ], "type": "list", "angle": 0, "index": 4, "blocks": [ { "bbox": [ 104, 79, 341, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 123, 79, 341, 92 ], "spans": [ { "bbox": [ 123, 79, 341, 92 ], "type": "text", "content": "这种扩展计算是整数型的计算，不支持浮点型。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 106, 507, 152 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 121, 106, 506, 120 ], "spans": [ { "bbox": [ 121, 106, 506, 120 ], "type": "text", "content": "如果表达式的结果为0，那么返回的退出状态码为1，或者是\"假\"，而一个非零值", "score": 1.0 } ] }, { "bbox": [ 124, 120, 506, 137 ], "spans": [ { "bbox": [ 124, 120, 506, 137 ], "type": "text", "content": "的表达式所返回的退出状态码将为 0，或者是\"true\"。若是逻辑判断，表达式 exp", "score": 1.0 } ] }, { "bbox": [ 124, 137, 224, 152 ], "spans": [ { "bbox": [ 124, 137, 224, 152 ], "type": "text", "content": "为真则为 1,假则为 0。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 164, 507, 195 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 116, 165, 505, 179 ], "spans": [ { "bbox": [ 116, 165, 505, 179 ], "type": "text", "content": "只要括号中的运算符、表达式符合 C 语言运算规则，都可用在$((exp))中，甚至是", "score": 1.0 } ] }, { "bbox": [ 124, 179, 179, 195 ], "spans": [ { "bbox": [ 124, 179, 179, 195 ], "type": "text", "content": "三目运算符", "score": 1.0 } ] } ] }, { "bbox": [ 104, 208, 507, 238 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 116, 208, 505, 221 ], "spans": [ { "bbox": [ 116, 208, 505, 221 ], "type": "text", "content": "作不同进位(如二进制、八进制、十六进制)运算时，输出结果全都自动转化成了十", "score": 1.0 } ] }, { "bbox": [ 123, 222, 154, 238 ], "spans": [ { "bbox": [ 123, 222, 154, 238 ], "type": "text", "content": "进制。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "type": "code", "bbox": [ 86, 251, 166, 264 ], "blocks": [ { "bbox": [ 86, 251, 166, 264 ], "lines": [ { "bbox": [ 86, 251, 166, 264 ], "spans": [ { "bbox": [ 86, 251, 166, 264 ], "type": "text", "content": "echo $((16#5f))" } ] } ], "index": 5, "angle": 0, "type": "code_body" } ], "index": 5, "sub_type": "code", "guess_lang": "lisp" }, { "bbox": [ 86, 279, 201, 292 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 279, 200, 292 ], "spans": [ { "bbox": [ 88, 279, 200, 292 ], "type": "text", "content": "95 #16 进制转 10 进制", "score": 1.0 } ] } ] }, { "bbox": [ 104, 333, 399, 375 ], "type": "list", "angle": 0, "index": 9, "blocks": [ { "bbox": [ 104, 333, 399, 348 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 105, 333, 400, 349 ], "spans": [ { "bbox": [ 105, 333, 400, 349 ], "type": "text", "content": " 用于算术运算比较，双括号中的变量可以不使用$符号前缀。", "score": 1.0 } ] } ] }, { "bbox": [ 104, 361, 285, 375 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 123, 362, 284, 375 ], "spans": [ { "bbox": [ 123, 362, 284, 375 ], "type": "text", "content": "括号内支持多个表达式用逗号分开", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 88, 396, 139, 414 ], "type": "title", "angle": 0, "index": 10, "lines": [ { "bbox": [ 87, 395, 140, 417 ], "spans": [ { "bbox": [ 87, 395, 140, 417 ], "type": "text", "content": "中括号", "score": 1.0 } ] } ] }, { "bbox": [ 86, 451, 221, 465 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 89, 451, 221, 465 ], "spans": [ { "bbox": [ 89, 451, 221, 465 ], "type": "text", "content": "中括号也可以进行整数运算。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 479, 135, 493 ], "type": "interline_equation", "angle": 0, "lines": [ { "bbox": [ 86, 479, 135, 493 ], "spans": [ { "bbox": [ 86, 479, 135, 493 ], "type": "interline_equation", "content": "\\mathsf {b} = \\mathbb {S} [ 1 + 3 ]", "image_path": "00545b6eda08158b5481e5fd78cfa3936b954556192de5926552b28ecd87a225.jpg" } ] } ], "index": 12 }, { "bbox": [ 87, 507, 130, 518 ], "type": "interline_equation", "angle": 0, "lines": [ { "bbox": [ 87, 507, 130, 518 ], "spans": [ { "bbox": [ 87, 507, 130, 518 ], "type": "interline_equation", "content": "e c h o \\mathbb {S} ^ {\\mathrm {b}}", "image_path": "ee77252ac94d680fb1356fb6e4b6fad53d0b4060bf0c114a03e79dfd88f3155b.jpg" } ] } ], "index": 13 }, { "bbox": [ 87, 534, 96, 545 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 88, 534, 98, 548 ], "spans": [ { "bbox": [ 88, 534, 98, 548 ], "type": "text", "content": "4", "score": 1.0 } ] } ] }, { "bbox": [ 87, 562, 107, 573 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 87, 561, 108, 576 ], "spans": [ { "bbox": [ 87, 561, 108, 576 ], "type": "text", "content": "Let", "score": 1.0 } ] } ] }, { "bbox": [ 86, 588, 508, 602 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 87, 587, 508, 607 ], "spans": [ { "bbox": [ 87, 588, 105, 605 ], "type": "text", "content": "let", "score": 1.0 }, { "bbox": [ 157, 587, 213, 605 ], "type": "text", "content": "内 置", "score": 1.0 }, { "bbox": [ 226, 588, 246, 603 ], "type": "text", "content": "命", "score": 1.0 }, { "bbox": [ 268, 588, 283, 603 ], "type": "text", "content": "令", "score": 1.0 }, { "bbox": [ 302, 587, 508, 607 ], "type": "text", "content": "用 于 算 术 运 算", "score": 1.0 } ] } ] }, { "bbox": [ 86, 604, 502, 618 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 87, 602, 500, 619 ], "spans": [ { "bbox": [ 87, 602, 500, 619 ], "type": "text", "content": "赋 值 符 号 和 运 算 符 两 边 不 能 留 空 格 ！", "score": 1.0 } ] } ] }, { "bbox": [ 101, 619, 506, 634 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 103, 619, 507, 634 ], "spans": [ { "bbox": [ 103, 619, 507, 634 ], "type": "text", "content": "如 果 将 字 符 串 赋 值 给 一 个 整 型 变 量 时 ， 则 变 量 的 值 为 0", "score": 1.0 } ] } ] }, { "bbox": [ 86, 635, 506, 649 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 105, 635, 508, 650 ], "spans": [ { "bbox": [ 105, 635, 508, 650 ], "type": "text", "content": "如 果 变 量 的 值 是 字 符 串 ， 则 进 行 算 术 运 算 时 设 为 0", "score": 1.0 } ] } ] }, { "bbox": [ 86, 651, 505, 664 ], "type": "text", "angle": 0, "index": 20, "lines": [ { "bbox": [ 86, 650, 506, 666 ], "spans": [ { "bbox": [ 86, 650, 105, 666 ], "type": "text", "content": "let", "score": 1.0 }, { "bbox": [ 217, 650, 262, 666 ], "type": "text", "content": "num2=4", "score": 1.0 }, { "bbox": [ 375, 654, 383, 663 ], "type": "text", "content": "+", "score": 1.0 }, { "bbox": [ 497, 652, 506, 665 ], "type": "text", "content": "1", "score": 1.0 } ] } ] }, { "bbox": [ 86, 666, 506, 681 ], "type": "text", "angle": 0, "index": 21, "lines": [ { "bbox": [ 88, 666, 506, 682 ], "spans": [ { "bbox": [ 88, 666, 506, 682 ], "type": "text", "content": "let \"num2=4 + 1\" # 用 引 号 忽 略 空 格 的 特 殊 含 义", "score": 1.0 } ] } ] }, { "bbox": [ 86, 682, 287, 696 ], "type": "text", "angle": 0, "index": 22, "lines": [ { "bbox": [ 89, 683, 286, 697 ], "spans": [ { "bbox": [ 89, 683, 286, 697 ], "type": "text", "content": "用 let 命令进行算术运算时，最好加双引号", "score": 1.0 } ] } ] }, { "bbox": [ 87, 711, 113, 723 ], "type": "text", "angle": 0, "index": 23, "lines": [ { "bbox": [ 86, 710, 115, 728 ], "spans": [ { "bbox": [ 86, 710, 115, 728 ], "type": "text", "content": "expr", "score": 1.0 } ] } ] }, { "bbox": [ 86, 737, 506, 751 ], "type": "text", "angle": 0, "index": 24, "lines": [ { "bbox": [ 86, 736, 506, 754 ], "spans": [ { "bbox": [ 86, 736, 103, 753 ], "type": "text", "content": "通", "score": 1.0 }, { "bbox": [ 132, 737, 146, 752 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 177, 736, 193, 752 ], "type": "text", "content": "的", "score": 1.0 }, { "bbox": [ 222, 737, 238, 752 ], "type": "text", "content": "表", "score": 1.0 }, { "bbox": [ 265, 737, 284, 753 ], "type": "text", "content": "达", "score": 1.0 }, { "bbox": [ 308, 736, 330, 754 ], "type": "text", "content": "式", "score": 1.0 }, { "bbox": [ 354, 737, 373, 753 ], "type": "text", "content": "计", "score": 1.0 }, { "bbox": [ 400, 737, 418, 753 ], "type": "text", "content": "算", "score": 1.0 }, { "bbox": [ 446, 737, 461, 752 ], "type": "text", "content": "命", "score": 1.0 }, { "bbox": [ 492, 737, 506, 751 ], "type": "text", "content": "令", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 29 }, { "para_blocks": [ { "bbox": [ 86, 78, 502, 108 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 88, 77, 500, 93 ], "spans": [ { "bbox": [ 88, 77, 500, 93 ], "type": "text", "content": "表 达 式 中 参 数 与 操 作 符 必 须 以 空 格 分 开 。", "score": 1.0 } ] }, { "bbox": [ 88, 94, 500, 109 ], "spans": [ { "bbox": [ 88, 94, 500, 109 ], "type": "text", "content": "表 达 式 中 的 运 算 可 以 是 算 术 运 算 ， 比 较 运 算 ， 字 符 串 运 算 和 逻 辑 运 算 。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 110, 505, 139 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 87, 109, 506, 124 ], "spans": [ { "bbox": [ 87, 109, 506, 124 ], "type": "text", "content": "expr \\( 2 + 5 \\) \\* 2 – 3 # 括 号 必 须 被 转 义", "score": 1.0 } ] }, { "bbox": [ 87, 124, 506, 140 ], "spans": [ { "bbox": [ 87, 125, 179, 139 ], "type": "text", "content": "expr 5 \\* 3", "score": 1.0 }, { "bbox": [ 285, 126, 298, 138 ], "type": "text", "content": "#", "score": 1.0 }, { "bbox": [ 315, 124, 506, 140 ], "type": "text", "content": "乘 法 符 号 必 须 被 转 义", "score": 1.0 } ] } ] }, { "bbox": [ 87, 141, 506, 170 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 87, 139, 506, 157 ], "spans": [ { "bbox": [ 87, 139, 116, 155 ], "type": "text", "content": "bash", "score": 1.0 }, { "bbox": [ 192, 140, 208, 156 ], "type": "text", "content": "只", "score": 1.0 }, { "bbox": [ 242, 141, 259, 157 ], "type": "text", "content": "支", "score": 1.0 }, { "bbox": [ 292, 140, 309, 156 ], "type": "text", "content": "持", "score": 1.0 }, { "bbox": [ 341, 141, 359, 155 ], "type": "text", "content": "整", "score": 1.0 }, { "bbox": [ 391, 141, 408, 155 ], "type": "text", "content": "数", "score": 1.0 }, { "bbox": [ 440, 141, 458, 155 ], "type": "text", "content": "运", "score": 1.0 }, { "bbox": [ 491, 141, 506, 155 ], "type": "text", "content": "算", "score": 1.0 } ] }, { "bbox": [ 88, 155, 506, 171 ], "spans": [ { "bbox": [ 88, 155, 267, 171 ], "type": "text", "content": "可 以 通 过 使 用 bc 或", "score": 1.0 }, { "bbox": [ 267, 156, 506, 171 ], "type": "text", "content": "awk 工 具 来 处 理 浮 点 数 运 算", "score": 1.0 } ] } ] }, { "bbox": [ 87, 172, 506, 201 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 170, 508, 186 ], "spans": [ { "bbox": [ 88, 173, 107, 184 ], "type": "inline_equation", "content": "\\mathsf { m } \\boldsymbol { = }", "score": 0.5 }, { "bbox": [ 107, 170, 131, 185 ], "type": "text", "content": "`awk", "score": 1.0 }, { "bbox": [ 256, 172, 373, 186 ], "type": "text", "content": "'BEGIN{x=2.45;y=3.123;", "score": 1.0 }, { "bbox": [ 497, 172, 508, 185 ], "type": "text", "content": "\\", "score": 1.0 } ] }, { "bbox": [ 277, 185, 508, 204 ], "spans": [ { "bbox": [ 277, 186, 312, 202 ], "type": "text", "content": "printf", "score": 1.0 }, { "bbox": [ 370, 185, 418, 203 ], "type": "text", "content": "\"%.3f\\n\",", "score": 1.0 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c字符型g/G浮点数（自动）
d十进制整数o八进制
e/E浮点数（科学计数法）s字符串
f浮点数（小数形式）x/X十六进制
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\\a警铃\\t水平制表符
\\b退后一格\\v垂直制表符
\\n换行\\反斜杠
\\f换页\\"双引号
\\r回车\\\\"百分号
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选项含义
-r将变量设为只读 (readonly)
-x将变量输出到子 shell 中 (export 为全局变量)
-i将变量设为整型 (integer)
-a将变量设置为一个数组 (array)
-f列出函数的名字和定义 (function)
-F只列出函数名
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"type": "text", "angle": 0, "index": 26, "lines": [ { "bbox": [ 88, 734, 134, 750 ], "spans": [ { "bbox": [ 88, 734, 134, 750 ], "type": "text", "content": "文件测试", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 31 }, { "para_blocks": [ { "type": "table", "bbox": [ 85, 74, 595, 715 ], "blocks": [ { "bbox": [ 85, 74, 595, 715 ], "lines": [ { "bbox": [ 85, 74, 595, 715 ], "spans": [ { "bbox": [ 85, 74, 595, 715 ], "type": "table", "html": "
[-f fname]fname存在且是普通文件时，返回真（即返回
[-L fname]fname存在且是链接文件时，返回真
[-d fname]fname存在且是一个目录时，返回真
[-e fname]fname（文件或目录）存在时，返回真
[-s fname]fname存在且大小大于0时，返回真
[-r fname]fname（文件或目录）存在且可读时，返回真
[-w fname]fname（文件或目录）存在且可写时，返回真
[-x fname]fname（文件或目录）存在且可执行时，返回
", "image_path": "307700d5c4bd9210b3ac1dfad7969c6506b415cea8a5131210c9b1eee67fc245.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" }, { "bbox": [ 88, 729, 143, 741 ], "lines": [ { "bbox": [ 89, 729, 143, 742 ], "spans": [ { "bbox": [ 89, 729, 143, 742 ], "type": "text", "content": "字符串测试", "score": 1.0 } ] } ], "index": 1, "angle": 0, "type": "table_footnote" } ], "index": 0 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 32 }, { "para_blocks": [ { "type": "table", "bbox": [ 85, 73, 594, 311 ], "blocks": [ { "bbox": [ 85, 73, 594, 311 ], "lines": [ { "bbox": [ 85, 73, 594, 311 ], "spans": [ { "bbox": [ 85, 73, 594, 311 ], "type": "table", "html": "
[-z string]如果字符串string长度为0，返回真
[-n string]如果字符串string长度不为0，返回真
[ str1 = str2]两字符串相等（也可使用==）返回真
[ str1 != str2]两字符串不等返回真
[[str1 == str2]]两字符串相同返回真
[[str1 != str2]]两字符串不相同返回真
[[str1~= str2]]str2是str1的子串返回真
[[str1 > str2]]str1大于str2返回真
[[str1 < str2]]str1小于str2返回真
", "image_path": "71c13866d42625288054f7d1afb6beff6f6da16f137b5fbbed104dcfc3b8513b.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 }, { "type": "table", "bbox": [ 86, 354, 594, 648 ], "blocks": [ { "bbox": [ 87, 324, 506, 353 ], "lines": [ { "bbox": [ 88, 323, 506, 339 ], "spans": [ { "bbox": [ 88, 323, 506, 339 ], "type": "text", "content": "字 符 串 按 从 左 到 右 对 应 字 符 的 ASCII 码 进 行 比 较", "score": 1.0 } ] }, { "bbox": [ 88, 339, 134, 354 ], "spans": [ { "bbox": [ 88, 339, 134, 354 ], "type": "text", "content": "整数测试", "score": 1.0 } ] } ], "index": 1, "angle": 0, "type": "table_caption" }, { "bbox": [ 86, 354, 594, 648 ], "lines": [ { "bbox": [ 86, 354, 594, 648 ], "spans": [ { "bbox": [ 86, 354, 594, 648 ], "type": "table", "html": "
[int1 -eq int2]int1 等于 int2 返回真
[int1 -ne int2]int1 不等于 int2 返回真
[int1 -gt int2]int1 大于 int2 返回真
[int1 -ge int2]int1 大于或等于 int2 返回真
[int1 -lt int2]int1 小于 int2 返回真
[int1 -le int2]int1 小于或等于 int2 返回真
[[int1 -eq int2]]int1 等于 int2 返回真
[[int1 -ne int2]]int1 不等于 int2 返回真
[[int1 -gt int2]]int1 大于 int2 返回真
[[int1 -ge int2]]int1 大于或等于 int2 返回真
[[int1 -lt int2]]int1 小于 int2 返回真
[[int1 -le int2]]int1 小于或等于 int2 返回真
", "image_path": "efef892f57431a44c56f72fc6926d78534b0af3acb6cd2fefcb2cbc378158e51.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "type": "table", "bbox": [ 86, 692, 593, 752 ], "blocks": [ { "bbox": [ 86, 663, 500, 678 ], "lines": [ { "bbox": [ 87, 661, 500, 682 ], "spans": [ { "bbox": [ 87, 662, 104, 679 ], "type": "text", "content": "操", "score": 1.0 }, { "bbox": [ 125, 662, 148, 679 ], "type": "text", "content": "作", "score": 1.0 }, { "bbox": [ 167, 662, 185, 679 ], "type": "text", "content": "符", "score": 1.0 }, { "bbox": [ 206, 661, 346, 682 ], "type": "text", "content": "两 边 必 须", "score": 1.0 }, { "bbox": [ 371, 663, 385, 678 ], "type": "text", "content": "留", "score": 1.0 }, { "bbox": [ 410, 663, 428, 679 ], "type": "text", "content": "空", "score": 1.0 }, { "bbox": [ 449, 662, 467, 679 ], "type": "text", "content": "格", "score": 1.0 }, { "bbox": [ 493, 666, 500, 677 ], "type": "text", "content": "！", "score": 1.0 } ] } ], "index": 3, "angle": 0, "type": "table_caption" }, { "bbox": [ 86, 692, 593, 752 ], "lines": [ { "bbox": [ 86, 692, 593, 752 ], "spans": [ { "bbox": [ 86, 692, 593, 752 ], "type": "table", "html": "
((int1 == int2))int1 等于 int2 返回真
((int1 != int2))int1 不等于 int2 返回真
((int1 > int2))int1 大于 int2 返回真
((int1 >= int2))int1 大于或等于 int2 返回真
((int1 < int2))int1 小于 int2 返回真
((int1 <= int2))int1 小于或等于 int2 返回真
", "image_path": "586d11fbd376e0677ba596d3e01193dec42d6d8d634dd0cdfecbe27d806d3662.jpg" } ] } ], "index": 4, "angle": 0, "type": "table_body" } ], "index": 4 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 33 }, { "para_blocks": [ { "type": "table", "bbox": [ 86, 76, 594, 190 ], "blocks": [ { "bbox": [ 86, 76, 594, 190 ], "lines": [], "index": 0, "angle": 0, "type": "table_body", "lines_deleted": true } ], "index": 0 }, { "bbox": [ 86, 191, 500, 205 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 85, 188, 504, 209 ], "spans": [ { "bbox": [ 85, 188, 504, 209 ], "type": "text", "content": "操 作 符 两 边 的 空 格 可 省 略 ！", "score": 1.0 } ] } ] }, { "bbox": [ 86, 222, 186, 235 ], "type": "title", "angle": 0, "index": 2, "lines": [ { "bbox": [ 89, 222, 185, 236 ], "spans": [ { "bbox": [ 89, 222, 185, 236 ], "type": "text", "content": "方括号前后要留空格", "score": 1.0 } ] } ] }, { "bbox": [ 86, 238, 500, 251 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 88, 236, 501, 255 ], "spans": [ { "bbox": [ 88, 239, 99, 254 ], "type": "text", "content": "[]", "score": 1.0 }, { "bbox": [ 127, 237, 146, 255 ], "type": "text", "content": "内", "score": 1.0 }, { "bbox": [ 173, 238, 191, 253 ], "type": "text", "content": "不", "score": 1.0 }, { "bbox": [ 219, 237, 236, 253 ], "type": "text", "content": "能", "score": 1.0 }, { "bbox": [ 264, 237, 281, 253 ], "type": "text", "content": "使", "score": 1.0 }, { "bbox": [ 309, 237, 326, 253 ], "type": "text", "content": "用", "score": 1.0 }, { "bbox": [ 355, 237, 371, 253 ], "type": "text", "content": "通", "score": 1.0 }, { "bbox": [ 401, 238, 417, 253 ], "type": "text", "content": "配", "score": 1.0 }, { "bbox": [ 445, 236, 462, 254 ], "type": "text", "content": "符", "score": 1.0 }, { "bbox": [ 492, 239, 501, 251 ], "type": "text", "content": "！", "score": 1.0 } ] } ] }, { "bbox": [ 86, 253, 304, 266 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 88, 253, 305, 268 ], "spans": [ { "bbox": [ 88, 253, 305, 268 ], "type": "text", "content": "在 [[]] 中可以使用 shell 的通配符进行条件匹配", "score": 1.0 } ] } ] }, { "bbox": [ 86, 269, 186, 282 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 89, 269, 185, 283 ], "spans": [ { "bbox": [ 89, 269, 185, 283 ], "type": "text", "content": "通配符与正则表达式", "score": 1.0 } ] } ] }, { "bbox": [ 105, 285, 158, 297 ], "type": "title", "angle": 0, "index": 6, "lines": [ { "bbox": [ 123, 285, 159, 300 ], "spans": [ { "bbox": [ 123, 285, 159, 300 ], "type": "text", "content": "通配符", "score": 1.0 } ] } ] }, { "bbox": [ 141, 301, 359, 345 ], "type": "list", "angle": 0, "index": 10, "blocks": [ { "bbox": [ 141, 301, 297, 313 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 141, 299, 299, 316 ], "spans": [ { "bbox": [ 141, 299, 299, 316 ], "type": "text", "content": "o 由 Shell 解析（如 bash, zsh）", "score": 1.0 } ] } ] }, { "bbox": [ 141, 316, 309, 328 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 141, 316, 309, 330 ], "spans": [ { "bbox": [ 141, 316, 309, 330 ], "type": "text", "content": "o 直接匹配文件名，无需外部工具", "score": 1.0 } ] } ] }, { "bbox": [ 141, 332, 359, 345 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 141, 332, 360, 347 ], "spans": [ { "bbox": [ 141, 332, 360, 347 ], "type": "text", "content": "o 例如 rm *.tmp 是 Shell 自身展开文件列表", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 105, 347, 179, 359 ], "type": "title", "angle": 0, "index": 11, "lines": [ { "bbox": [ 123, 348, 180, 363 ], "spans": [ { "bbox": [ 123, 348, 180, 363 ], "type": "text", "content": "正则表达式", "score": 1.0 } ] } ] }, { "bbox": [ 141, 363, 359, 391 ], "type": "list", "angle": 0, "index": 14, "blocks": [ { "bbox": [ 141, 363, 359, 376 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 141, 362, 360, 379 ], "spans": [ { "bbox": [ 141, 362, 360, 379 ], "type": "text", "content": "o 由文本处理工具解析（grep, sed, awk 等）", "score": 1.0 } ] } ] }, { "bbox": [ 141, 379, 320, 391 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 141, 379, 320, 391 ], "spans": [ { "bbox": [ 141, 379, 320, 391 ], "type": "text", "content": "o 匹配文本内容，支持更复杂的模式", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "type": "table", "bbox": [ 86, 407, 594, 729 ], "blocks": [ { "bbox": [ 87, 394, 132, 407 ], "lines": [ { "bbox": [ 88, 394, 134, 408 ], "spans": [ { "bbox": [ 88, 394, 134, 408 ], "type": "text", "content": "逻辑测试", "score": 1.0 } ] } ], "index": 15, "angle": 0, "type": "table_caption" }, { "bbox": [ 86, 407, 594, 729 ], "lines": [ { "bbox": [ 86, 407, 594, 729 ], "spans": [ { "bbox": [ 86, 407, 594, 729 ], "type": "table", "html": "
[ expr1 -a expr2 ]逻辑与，都为真时，结果为真
[ expr1 -o expr2 ]逻辑或，有一个为真时，结果为真
[! expr ]逻辑非
[ [ pattern1 && pattern2 ]]逻辑与
[ [ pattern1 | | pattern2 ]]逻辑或
[! ! pattern ]]逻辑非
(( expr1 && expr2 ))逻辑与
(( expr1 | | expr2 ))逻辑或
([! expr ))逻辑非
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"content": "能", "score": 1.0 }, { "bbox": [ 266, 78, 283, 94 ], "type": "text", "content": "随", "score": 1.0 }, { "bbox": [ 311, 78, 329, 94 ], "type": "text", "content": "便", "score": 1.0 }, { "bbox": [ 356, 78, 373, 94 ], "type": "text", "content": "添", "score": 1.0 }, { "bbox": [ 401, 78, 418, 94 ], "type": "text", "content": "加", "score": 1.0 }, { "bbox": [ 446, 78, 462, 94 ], "type": "text", "content": "括", "score": 1.0 }, { "bbox": [ 492, 78, 506, 94 ], "type": "text", "content": "号", "score": 1.0 } ] } ] }, { "bbox": [ 86, 110, 506, 122 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 85, 105, 509, 128 ], "spans": [ { "bbox": [ 85, 105, 509, 128 ], "type": "text", "content": "(( $x == 1 )) && [[ $name = To? ]]; echo $?", "score": 1.0 } ] } ] }, { "bbox": [ 86, 125, 500, 138 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 88, 125, 499, 141 ], "spans": [ { "bbox": [ 88, 125, 499, 141 ], "type": "text", "content": "此 处 的 && 并 非 逻 辑 运 算 符 ， 而 是 命 令 聚 合 （ Command Group ）", "score": 1.0 } ] } ] }, { "bbox": [ 86, 174, 170, 193 ], "type": "title", "angle": 0, "index": 3, "lines": [ { "bbox": [ 86, 174, 171, 195 ], "spans": [ { "bbox": [ 86, 174, 171, 195 ], "type": "text", "content": "if 分支结构", "score": 1.0 } ] } ] }, { "bbox": [ 86, 230, 506, 259 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 89, 231, 506, 244 ], "spans": [ { "bbox": [ 89, 231, 506, 244 ], "type": "text", "content": "一般是对逻辑表达式进行判断。根据逻辑表达式的真、假，分走不同的分支。这个表达式", "score": 1.0 } ] }, { "bbox": [ 89, 247, 179, 260 ], "spans": [ { "bbox": [ 89, 247, 179, 260 ], "type": "text", "content": "也称为条件表达式。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 274, 151, 286 ], "type": "title", "angle": 0, "index": 5, "lines": [ { "bbox": [ 88, 274, 151, 288 ], "spans": [ { "bbox": [ 88, 274, 151, 288 ], "type": "text", "content": "1.1 语法格式", "score": 1.0 } ] } ] }, { "bbox": [ 86, 301, 285, 316 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 88, 300, 285, 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"bbox": [ 98, 703, 158, 717 ], "spans": [ { "bbox": [ 98, 703, 158, 717 ], "type": "text", "content": "command2", "score": 1.0 } ] } ] }, { "bbox": [ 98, 735, 110, 743 ], "type": "text", "angle": 0, "index": 21, "lines": [] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 35 }, { "para_blocks": [ { "type": "code", "bbox": [ 88, 79, 160, 174 ], "blocks": [ { "bbox": [ 88, 79, 160, 174 ], "lines": [ { "bbox": [ 88, 79, 160, 174 ], "spans": [ { "bbox": [ 88, 79, 160, 174 ], "type": "text", "content": "commandN else command fi" } ] } ], "index": 0, "angle": 0, "type": "code_body" } ], "index": 0, "sub_type": "code", "guess_lang": "txt" }, { "type": "code", "bbox": [ 88, 243, 160, 476 ], "blocks": [ { "bbox": [ 87, 216, 184, 229 ], "lines": [ { "bbox": [ 88, 216, 185, 232 ], "spans": [ { "bbox": [ 88, 216, 185, 232 ], "type": "text", "content": "格式三：if-elif-else", "score": 1.0 } ] } ], "index": 1, "angle": 0, "type": "code_caption" }, { "bbox": [ 88, 243, 160, 476 ], "lines": [ { "bbox": [ 88, 243, 160, 476 ], "spans": [ { "bbox": [ 88, 243, 160, 476 ], "type": "text", "content": "if cond_cmd \nthen command1 \nelif con_cmd2 \nthen command2 \nelse commandN \nfi" } ] } ], "index": 2, "angle": 0, "type": "code_body" } ], "index": 2, "sub_type": "code", "guess_lang": "txt" }, { "bbox": [ 86, 492, 505, 537 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 89, 493, 505, 504 ], "spans": [ { "bbox": [ 89, 493, 505, 504 ], "type": "text", "content": "if 其实是判断其后面的命令是否执行成功为分支条件的，因此 if 之后不一定必须是test 命", "score": 1.0 } ] }, { "bbox": [ 89, 508, 505, 522 ], "spans": [ { "bbox": [ 89, 508, 505, 522 ], "type": "text", "content": "令，可以是任何其他的命令，只是这些命令一般不需要其输出，因为只需要知道执行成功", "score": 1.0 } ] }, { "bbox": [ 89, 524, 364, 537 ], "spans": [ { "bbox": [ 89, 524, 364, 537 ], "type": "text", "content": "与否，输出并不重要，一般就通过重定向到/dev/null 解决。", "score": 1.0 } ] } ] }, { "type": "code", "bbox": [ 86, 550, 508, 706 ], "blocks": [ { "bbox": [ 86, 550, 508, 706 ], "lines": [ { "bbox": [ 86, 550, 508, 706 ], "spans": [ { "bbox": [ 86, 550, 508, 706 ], "type": "text", "content": "if expr1 # 如果 expr1 为真（返回值为0) then # 那么 commands1 # 执行语句块 commands1 elif expr2 # 若 expr1 不真，而 expr2 为真 then # 那么 commands2 # 执行语句块 commands2 ... ... # 可以有多个 elif 语句 else # else 最多只能有一个 commands4 fi # if 语句必须以单词 fi 终止" } ] } ], "index": 4, "angle": 0, "type": "code_body" } ], "index": 4, "sub_type": "code", "guess_lang": "txt" } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 36 }, { "para_blocks": [ { "bbox": [ 99, 77, 411, 242 ], "type": "list", "angle": 0, "index": 6, "blocks": [ { "bbox": [ 99, 77, 312, 90 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 101, 76, 312, 91 ], "spans": [ { "bbox": [ 101, 76, 114, 91 ], "type": "inline_equation", "content": "\\spadesuit", "score": 0.71 }, { "bbox": [ 105, 81, 111, 86 ], "type": "text", "content": "", "score": 0.0 }, { "bbox": [ 114, 76, 312, 91 ], "type": "text", "content": "elif可以有任意多个（o个或多个)", "score": 0.942 } ] } ] }, { "bbox": [ 100, 96, 314, 111 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 101, 95, 314, 111 ], "spans": [ { "bbox": [ 101, 96, 114, 111 ], "type": "inline_equation", "content": "\\bullet", "score": 0.79 }, { "bbox": [ 101, 100, 115, 108 ], "type": "text", "content": "", "score": 0.0 }, { "bbox": [ 114, 95, 314, 111 ], "type": "text", "content": "else最多只能有一个 (o个或1个)", "score": 0.958 } ] } ] }, { "bbox": [ 100, 116, 268, 131 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 101, 116, 266, 131 ], "spans": [ { "bbox": [ 101, 116, 114, 131 ], "type": "inline_equation", "content": "\\bullet", "score": 0.83 }, { "bbox": [ 115, 116, 266, 131 ], "type": "text", "content": "if 语句必须以fi表示结束", "score": 0.96 } ] } ] }, { "bbox": [ 99, 139, 411, 169 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 115, 138, 413, 156 ], "spans": [ { "bbox": [ 115, 138, 413, 156 ], "type": "text", "content": "exprx通常为条件测试表达式；也可以是多个命令，以", "score": 0.989 } ] }, { "bbox": [ 100, 154, 290, 170 ], "spans": [ { "bbox": [ 100, 154, 290, 170 ], "type": "text", "content": "最后一个命令的退出状态为条件值。", "score": 0.999 } ] } ] }, { "bbox": [ 99, 176, 411, 221 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 101, 176, 412, 190 ], "spans": [ { "bbox": [ 101, 177, 114, 190 ], "type": "inline_equation", "content": "\\cdot", "score": 0.68 }, { "bbox": [ 116, 176, 412, 190 ], "type": "text", "content": "commands为可执行语句块，如果为空，需使用shell", "score": 0.987 } ] }, { "bbox": [ 99, 188, 412, 207 ], "spans": [ { "bbox": [ 99, 188, 412, 207 ], "type": "text", "content": "提供的空命令“：”，即冒号。该命令不做任何事情，只", "score": 0.996 } ] }, { "bbox": [ 101, 206, 211, 222 ], "spans": [ { "bbox": [ 101, 206, 211, 222 ], "type": "text", "content": "返回一个退出状态0", "score": 0.989 } ] } ] }, { "bbox": [ 100, 227, 233, 242 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 101, 227, 232, 242 ], "spans": [ { "bbox": [ 101, 227, 114, 242 ], "type": "inline_equation", "content": "\\bullet", "score": 0.72 }, { "bbox": [ 115, 227, 232, 242 ], "type": "text", "content": "if语句可以嵌套使用", "score": 0.998 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 333, 444, 346 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 88, 333, 445, 347 ], "spans": [ { "bbox": [ 88, 333, 445, 347 ], "type": "text", "content": "case 结构适合取值确定的多种情况的判断，但是也支持带通配符的模糊判断。", "score": 1.0 } ] } ] }, { "bbox": [ 87, 367, 193, 386 ], "type": "title", "angle": 0, "index": 8, "lines": [ { "bbox": [ 85, 365, 196, 387 ], "spans": [ { "bbox": [ 85, 365, 196, 387 ], "type": "text", "content": "case语法格式", "score": 1.0 } ] } ] }, { "bbox": [ 86, 423, 498, 451 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 88, 422, 499, 436 ], "spans": [ { "bbox": [ 88, 422, 499, 436 ], "type": "text", "content": "Shell case 语句为多选择语句。可以用 case 语句匹配一个值与一个模式，如果匹配成功，", "score": 1.0 } ] }, { "bbox": [ 88, 438, 277, 452 ], "spans": [ { "bbox": [ 88, 438, 277, 452 ], "type": "text", "content": "执行相匹配的命令。case 语句格式如下：", "score": 1.0 } ] } ] }, { "bbox": [ 87, 466, 137, 478 ], "type": "text", "angle": 0, "index": 10, "lines": [ { "bbox": [ 87, 464, 139, 481 ], "spans": [ { "bbox": [ 87, 464, 139, 481 ], "type": "text", "content": "case 值 in", "score": 1.0 } ] } ] }, { "bbox": [ 87, 493, 123, 506 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 87, 491, 126, 510 ], "spans": [ { "bbox": [ 87, 491, 126, 510 ], "type": "text", "content": "模式 1)", "score": 1.0 } ] } ] }, { "bbox": [ 98, 521, 156, 533 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 99, 523, 157, 534 ], "spans": [ { "bbox": [ 99, 523, 157, 534 ], "type": "text", "content": "command1", "score": 1.0 } ] } ] }, { "bbox": [ 98, 549, 157, 560 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 98, 549, 158, 562 ], "spans": [ { "bbox": [ 98, 549, 158, 562 ], "type": "text", "content": "command2", "score": 1.0 } ] } ] }, { "bbox": [ 98, 581, 110, 588 ], "type": "text", "angle": 0, "index": 14, "lines": [] }, { "bbox": [ 98, 603, 158, 615 ], "type": "text", "angle": 0, "index": 15, "lines": [ { "bbox": [ 99, 604, 160, 617 ], "spans": [ { "bbox": [ 99, 604, 160, 617 ], "type": "text", "content": "commandN", "score": 1.0 } ] } ] }, { "bbox": [ 98, 634, 107, 643 ], "type": "text", "angle": 0, "index": 16, "lines": [ { "bbox": [ 101, 634, 105, 638 ], "spans": [ { "bbox": [ 101, 634, 105, 638 ], "type": "text", "content": "", "score": 0.0 } ] }, { "bbox": [ 100, 639, 107, 645 ], "spans": [ { "bbox": [ 100, 639, 107, 645 ], "type": "text", "content": "", "score": 0.0 } ] } ] }, { "bbox": [ 87, 659, 123, 671 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 88, 658, 124, 674 ], "spans": [ { "bbox": [ 88, 658, 124, 674 ], "type": "text", "content": "模式 2）", "score": 1.0 } ] } ] }, { "bbox": [ 98, 687, 156, 698 ], "type": "text", "angle": 0, "index": 18, "lines": [ { "bbox": [ 99, 687, 157, 699 ], "spans": [ { "bbox": [ 99, 687, 157, 699 ], "type": "text", "content": "command1", "score": 1.0 } ] } ] }, { "bbox": [ 98, 714, 157, 726 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 98, 714, 158, 727 ], "spans": [ { "bbox": [ 98, 714, 158, 727 ], "type": "text", "content": "command2", "score": 1.0 } ] } ] }, { "bbox": [ 98, 746, 110, 754 ], "type": "text", "angle": 0, "index": 20, "lines": [] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 37 }, { "para_blocks": [ { "bbox": [ 99, 79, 158, 89 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 99, 79, 160, 91 ], "spans": [ { "bbox": [ 99, 79, 160, 91 ], "type": "text", "content": "commandN", "score": 1.0 } ] } ] }, { "bbox": [ 88, 135, 113, 144 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 88, 136, 114, 148 ], "spans": [ { "bbox": [ 88, 136, 114, 148 ], "type": "text", "content": "esac", "score": 1.0 } ] } ] }, { "bbox": [ 104, 189, 504, 411 ], "type": "list", "angle": 0, "index": 10, "blocks": [ { "bbox": [ 104, 189, 345, 201 ], "type": "text", "angle": 0, "index": 2, "lines": [ { "bbox": [ 108, 189, 347, 204 ], "spans": [ { "bbox": [ 108, 189, 347, 204 ], "type": "text", "content": " case 之后是取值，所以变量名之前不要忘记了$", "score": 1.0 } ] } ] }, { "bbox": [ 105, 216, 232, 229 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 123, 217, 232, 230 ], "spans": [ { "bbox": [ 123, 217, 232, 230 ], "type": "text", "content": "取值后面必须为单词in", "score": 1.0 } ] } ] }, { "bbox": [ 105, 244, 271, 257 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 107, 244, 271, 258 ], "spans": [ { "bbox": [ 107, 244, 271, 258 ], "type": "text", "content": " 每一模式必须以右小括号) 结束", "score": 1.0 } ] } ] }, { "bbox": [ 105, 272, 231, 284 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 124, 272, 232, 285 ], "spans": [ { "bbox": [ 124, 272, 232, 285 ], "type": "text", "content": "取值可以为变量或常数", "score": 1.0 } ] } ] }, { "bbox": [ 104, 299, 504, 327 ], "type": "text", "angle": 0, "index": 6, "lines": [ { "bbox": [ 124, 299, 506, 313 ], "spans": [ { "bbox": [ 124, 299, 506, 313 ], "type": "text", "content": "匹配发现取值符合某一模式后，其间所有命令开始执行直至双分 ;; 号结束，表示", "score": 1.0 } ] }, { "bbox": [ 123, 313, 157, 329 ], "spans": [ { "bbox": [ 123, 313, 157, 329 ], "type": "text", "content": "break", "score": 1.0 } ] } ] }, { "bbox": [ 105, 342, 336, 355 ], "type": "text", "angle": 0, "index": 7, "lines": [ { "bbox": [ 123, 343, 336, 356 ], "spans": [ { "bbox": [ 123, 343, 336, 356 ], "type": "text", "content": "执行完匹配模式相应命令后不再继续其他模式", "score": 1.0 } ] } ] }, { "bbox": [ 104, 370, 409, 383 ], "type": "text", "angle": 0, "index": 8, "lines": [ { "bbox": [ 104, 370, 410, 384 ], "spans": [ { "bbox": [ 104, 370, 410, 384 ], "type": "text", "content": " 如果无一匹配模式，使用星号* 捕获该值，再执行后面的命令", "score": 1.0 } ] } ] }, { "bbox": [ 105, 397, 356, 411 ], "type": "text", "angle": 0, "index": 9, "lines": [ { "bbox": [ 123, 396, 357, 412 ], "spans": [ { "bbox": [ 123, 396, 357, 412 ], "type": "text", "content": "需要一个 esac（就是 case 反过来）作为结束标记", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 121, 444, 411, 572 ], "type": "list", "angle": 0, "index": 15, "blocks": [ { "bbox": [ 122, 444, 405, 470 ], "type": "text", "angle": 0, "index": 11, "lines": [ { "bbox": [ 124, 444, 406, 458 ], "spans": [ { "bbox": [ 124, 445, 136, 457 ], "type": "inline_equation", "content": "\\cdot", "score": 0.76 }, { "bbox": [ 136, 444, 406, 458 ], "type": "text", "content": "表达式expr按顺序匹配每个模式，一旦有一个模式匹配", "score": 0.998 } ] }, { "bbox": [ 123, 456, 384, 473 ], "spans": [ { "bbox": [ 123, 456, 384, 473 ], "type": "text", "content": "成功，则执行该模式后面的所有命令，然后退出case。", "score": 1.0 } ] } ] }, { "bbox": [ 121, 480, 411, 506 ], "type": "text", "angle": 0, "index": 12, "lines": [ { "bbox": [ 124, 478, 414, 494 ], "spans": [ { "bbox": [ 124, 480, 136, 492 ], "type": "inline_equation", "content": "\\bullet", "score": 0.69 }, { "bbox": [ 136, 478, 414, 494 ], "type": "text", "content": "如果expr 没有找到匹配的模式，则执行缺省值“*）”后", "score": 0.986 } ] }, { "bbox": [ 124, 491, 405, 509 ], "spans": [ { "bbox": [ 124, 491, 304, 508 ], "type": "text", "content": "面的命令块(类似于if 中的else);", "score": 0.941 }, { "bbox": [ 309, 491, 405, 509 ], "type": "text", "content": "\"*)”可以不出现。", "score": 0.863 } ] } ] }, { "bbox": [ 122, 520, 398, 533 ], "type": "text", "angle": 0, "index": 13, "lines": [ { "bbox": [ 124, 520, 398, 534 ], "spans": [ { "bbox": [ 124, 521, 136, 533 ], "type": "inline_equation", "content": "\\bullet", "score": 0.71 }, { "bbox": [ 136, 520, 391, 534 ], "type": "text", "content": "所给的匹配模式pattern中可以含有通配符和“」”", "score": 0.99 }, { "bbox": [ 394, 528, 398, 532 ], "type": "text", "content": "", "score": 0.0 } ] } ] }, { "bbox": [ 121, 546, 405, 572 ], "type": "text", "angle": 0, "index": 14, "lines": [ { "bbox": [ 124, 545, 406, 560 ], "spans": [ { "bbox": [ 124, 548, 136, 559 ], "type": "inline_equation", "content": "\\bullet", "score": 0.67 }, { "bbox": [ 136, 545, 406, 560 ], "type": "text", "content": "每个命令块的最后必须有一个双分号，可以独占一行，或", "score": 1.0 } ] }, { "bbox": [ 124, 559, 248, 573 ], "spans": [ { "bbox": [ 124, 559, 248, 573 ], "type": "text", "content": "放在最后一个命令的后面。", "score": 1.0 } ] } ] } ], "sub_type": "text" }, { "bbox": [ 86, 615, 236, 634 ], "type": "title", "angle": 0, "index": 16, "lines": [ { "bbox": [ 87, 614, 239, 635 ], "spans": [ { "bbox": [ 87, 614, 239, 635 ], "type": "text", "content": "for 循环一般格式为：", "score": 1.0 } ] } ] }, { "bbox": [ 86, 671, 241, 682 ], "type": "text", "angle": 0, "index": 17, "lines": [ { "bbox": [ 89, 671, 241, 684 ], "spans": [ { "bbox": [ 89, 671, 241, 684 ], "type": "text", "content": "for var in item1 item2 ... itemN", "score": 1.0 } ] } ] }, { "bbox": [ 88, 699, 102, 709 ], "type": "text", "angle": 0, "index": 18, "lines": [] }, { "bbox": [ 98, 727, 155, 737 ], "type": "text", "angle": 0, "index": 19, "lines": [ { "bbox": [ 98, 727, 157, 739 ], "spans": [ { "bbox": [ 98, 727, 157, 739 ], "type": 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500, 576 ], "spans": [ { "bbox": [ 88, 561, 500, 576 ], "type": "text", "content": "Linux 的 大 部 分 命 令 都 具 有 标 准 的 输 入 / 输 出 设 备 端 口 。", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 591, 594, 718 ], "blocks": [ { "bbox": [ 88, 591, 594, 718 ], "lines": [ { "bbox": [ 88, 591, 594, 718 ], "spans": [ { "bbox": [ 88, 591, 594, 718 ], "type": "table", "html": "
名称文件描述符含义设备说明
STDIN0标准输入键盘命令在执行时所要的输入通过它来取得
STDOUT1标准输出显示器命令执行后的输出结果从该端口送出
STDERR2标准错误显示器命令执行时的错误信息通过该端口送出
", "image_path": "b7661213680e3ff117ddcc2c70c46427fd4ac9ca78bb4ddd9c953bfaac41201e.jpg" } ] } ], "index": 29, "angle": 0, "type": "table_body" } ], "index": 29 }, { "bbox": [ 86, 721, 506, 751 ], "type": "text", "angle": 0, "index": 30, "lines": [ { "bbox": [ 89, 721, 505, 735 ], "spans": [ { "bbox": [ 89, 721, 505, 735 ], "type": "text", "content": "所谓重定向，就是不使用系统的标准输入端口、标准输出端口或标准错误端口，而进行重", "score": 1.0 } ] }, { "bbox": [ 89, 738, 504, 749 ], "spans": [ { "bbox": [ 89, 738, 504, 749 ], "type": "text", "content": "新的指定，所以重定向分为输出重定向、输入重定向和错误重定向。通常情况下重定向到", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 47 }, { "para_blocks": [ { "bbox": [ 86, 79, 500, 92 ], "type": "text", "angle": 0, "index": 0, "lines": [ { "bbox": [ 188, 76, 499, 96 ], "spans": [ { "bbox": [ 188, 76, 205, 96 ], "type": "text", "content": "个", "score": 1.0 }, { "bbox": [ 288, 77, 306, 96 ], "type": "text", "content": "文", "score": 1.0 }, { "bbox": [ 390, 77, 406, 95 ], "type": "text", "content": "件", "score": 1.0 }, { "bbox": [ 493, 85, 499, 92 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "bbox": [ 86, 94, 505, 123 ], "type": "text", "angle": 0, "index": 1, "lines": [ { "bbox": [ 89, 95, 505, 108 ], "spans": [ { "bbox": [ 89, 95, 505, 108 ], "type": "text", "content": "在Shell中，要实现重定向主要依靠重定向符实现，即 Shell是检查命令行中有无重定向符", "score": 1.0 } ] }, { "bbox": [ 86, 108, 499, 125 ], "spans": [ { "bbox": [ 86, 108, 474, 125 ], "type": "text", "content": "来 决 定 是 否 需 要 实 施 重 定 向", "score": 1.0 }, { "bbox": [ 491, 116, 499, 123 ], "type": "text", "content": "。", "score": 1.0 } ] } ] }, { "type": "table", "bbox": [ 88, 139, 595, 727 ], "blocks": [ { "bbox": [ 88, 139, 595, 727 ], "lines": [ { "bbox": [ 88, 139, 595, 727 ], "spans": [ { "bbox": [ 88, 139, 595, 727 ], "type": "table", "html": "
重定向符说明
<输入重定向
<<!输入重定向的特例,即HERE文件,通常用于Shell脚本中。其中“!”可以仅只要其没在……中出现过即可。
!
>覆盖式的输出重定向
>>追加式的输出重定向
2>覆盖式的错误输出重定向
2>>追加式的错误输出重定向
&>同时实现输出重定向和错误重定向(覆盖式)
空 设 备 (/dev/null)
空 设 备 是 个 黑 洞,发 往 它 的 任 何 内 容 都 将 不 复 存 在
经常 用于 屏 蔽 命 令 的 输 出 或 错 误 输出,尤其用于 Shell 脚 本 中
空 设 备 使 用 举 例
屏蔽 命 令 的 输 出 和 错 误 输 出 /dev/null
$ myprogram &>/dev/null
$ myprogram >/dev/null 2>&1
清 空 文 件 内 容
$ cp /dev/null myfile
$ > myfile
命令替换
使用 命 令 的 输 出 ,常 用 于
在 文 本 中 嵌 入 命 令 的 执 行 结 果
命令 参 数 是 另 一 个 命 令 执 行 的 结 果
使 用 方 法
$(command) 或 `command`
cmd1 $(cmd2) 或 cmd1 `cmd2`
使 用 举 例
$ echo The present time is `date`
$ rpm -qi $(rpm -qf $(which date)) # 嵌 套
命令组合
", "image_path": "ae8a233e1f7347f880789d75f607096032d0d4e3b8e13b814b8ce88f9fa05796.jpg" } ] } ], "index": 2, "angle": 0, "type": "table_body" } ], "index": 2 }, { "bbox": [ 94, 734, 150, 748 ], "type": "text", "angle": 0, "index": 3, "lines": [ { "bbox": [ 93, 732, 152, 750 ], "spans": [ { "bbox": [ 93, 732, 152, 750 ], "type": "text", "content": "命令行形式", "score": 1.0 } ] } ] }, { "bbox": [ 299, 734, 323, 747 ], "type": "text", "angle": 0, "index": 4, "lines": [ { "bbox": [ 297, 731, 326, 749 ], "spans": [ { "bbox": [ 297, 731, 326, 749 ], "type": "text", "content": "说明", "score": 1.0 } ] } ] }, { "bbox": [ 527, 734, 550, 747 ], "type": "text", "angle": 0, "index": 5, "lines": [ { "bbox": [ 525, 731, 552, 749 ], "spans": [ { "bbox": [ 525, 731, 552, 749 ], "type": "text", "content": "举例", "score": 1.0 } ] } ] } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 48 }, { "para_blocks": [ { "type": "table", "bbox": [ 88, 76, 595, 239 ], "blocks": [ { "bbox": [ 88, 76, 595, 239 ], "lines": [ { "bbox": [ 88, 76, 595, 239 ], "spans": [ { "bbox": [ 88, 76, 595, 239 ], "type": "table", "html": "
CMD1; CMD2顺序执行若干命令pwd;date;ls
CMD1 && CMD2当CMD1运行成功时才运行CMD2gzip mylargef
CMD1 || CMD2当CMD1运行失败时才运行CMD2write osmonc\nmy.log
(CMDLIST)在子Shell中执行命令序列(date; who | v)
{CMDLIST}在当前Shell中执行命令序列{cd /home/jjh}
", "image_path": "1b2f5d09e741800ebdacbd78c268f11db67f138c98b9c31c6dd02f44ada08cbf.jpg" } ] } ], "index": 0, "angle": 0, "type": "table_body" } ], "index": 0 } ], "discarded_blocks": [], "page_size": [ 595, 841 ], "page_idx": 49 } ], "_backend": "hybrid", "_ocr_enable": false, "_vlm_ocr_enable": false, "_version_name": "2.7.6" }