關於 linux shell if ，我們在網路上蒐集到這些相關的討論、資訊與評價

#11. linux 下shell中if的“-e，-d，-f”是什么意思

e filename 如果filename存在，则为真-d filename 如果filename为目录，则为真-f filename 如果filename为常规文件，则为真-L filename 如果filename ...

#12. shell中的if语句- 开始认识- 博客园

1、基本语法: 2、扩展语法： 3、语法说明： bash shell会按顺序执行if语句，如果command执行后且它的返回状态是0，则会执行符合该条件执行的语句， ...

#13. Shell if else语句（详解版） - C语言中文网

#!/bin/bash · read a · read b · if (( $a == $b )) · then · echo "a和b相等" ...

#14. Shell Script : if 條件式 - 兩隻小虎,一隻豬- 痞客邦

在shell script 中if 條件式的基本語法如下if [ CONDITION ] then ...... else ...... fi if test CO.

#15. One Line if-else Condition in Linux Shell Scripting - Baeldung

As the ubiquitous Linux shell, Bash has its own features and scripting syntax, which upgrade those of the regular sh shell.

#16. 第十二章、學習Shell Scripts - 鳥哥的Linux 私房菜

12.4.1 利用if .... then： 單層簡單條件, 多重複雜條件, 檢驗$1內容, ... 因為shell script 用的是外部的指令與bash shell 的一些預設工具，所以，他常常會去呼叫外部 ...

#17. If..else..fi - Linux Bash Shell Scripting Tutorial Wiki - nixCraft

if..else..fi allows to make choice based on the success or failure of a command. For example, find out if file exists (true condition) or not (false ...

#18. Unix / Linux Shell - The if...elif...fi statement - Tutorialspoint

This code is just a series of if statements, where each if is part of the else clause of the previous statement. Here statement(s) are executed based on the ...

#19. Conditions in bash scripting (if statements) - A Cloud Guru

The basic rules of bash conditions · You can invert a condition by putting an “!” in front of it. Example: if [ ! -f regularfile ]; then · You can ...

#20. Shell if...elif...fi 語句 - 極客書

if...elif...fi語句是提前一個級彆的控製語句，形式出幾個條件，允許Shell 作出正確的決定。 Syntax: if [ expression 1 ] then Statement ( s ) to be executed if ...

#21. Bash: If, Else If, Else Examples - Linux Hint

When using IF conditions in Bash, you can optionally introduce ELIF conditions that will provide different actions depending on which of a group of conditions ...

#22. Bash if elif else Statement: A Comprehensive Tutorial

Bash scripts help automate tasks on your machine. The if elif else statement in bash scripts allows creating conditional cases and responses to ...

#23. Bash If Statement – Linux Shell If-Else Syntax Example

Bash If Statement – Linux Shell If-Else Syntax Example ; if [ condition ] · statement ; #! /bin/sh a=5 b=30 · $a -lt $b ] then echo "a is less than b" ...

#24. 第二十一章Shell Script - twbsd.org

說明：上面這一個程式是檢查/etc/motd 這個檔案是否可以讀，如果可以則印出該檔案，否則印出檔案不可讀。 範例二： $ ee test.sh. #!/bin/sh if [ $1 -gt 5 ] then echo " ...

#25. LINUX SHELL多条件（与、或）if判断怎么写？ - 51CTO博客

LINUX SHELL 多条件（与、或）if判断怎么写？，经过测试，如下写法正确：if[[$a==$b||$c==$d]];thenechoOKfi.

#26. Linux Shell教程（一） / if else语句与test结合使用

Shell 是用户使用Unix/Linux的桥梁，用户的大部分工作都是通过shell完成的。它虽然不是Unix/Linux系统内核的一部分， ... if ... else 语句也经常与test 命令结合使用。

#27. If Statements - Bash Scripting Tutorial

If statements (and, closely related, case statements) allow us to make decisions in our Bash scripts. They allow us to decide whether or not to run a piece of ...

#28. shell中条件判断if中-z到-d的意思 - 腾讯云

linux 学习第六十四篇：Shell脚本中的逻辑判断，文件目录属性判断， if特殊用法，case判断. Shell脚本中的逻辑判断格式1：if 条件; then 语句; fi 格式2： ...

#29. Shell if - GitBook

Shell if. #Brief if,else,fi语句的语法。 if [ expression ] ... 也成一行则需要用;. if test -f "$FILE"; then echo "true"; fi. #Command ...

#30. Conditional Statements | Shell Script - GeeksforGeeks

Conditional Statements | Shell Script ... This block will process if specified condition is true. ... If specified condition is not true in if part ...

#31. Bash if..else Statement | Linuxize

This tutorial will walk you through the basics of the Bash if Statement and show you how to use it in your shell scripts.

#32. How to use IF ELSE statements in Shell Scripts - Serverlab

IF ELIF Bash Statement. Multiple IF tests can be used within a single IF statement block. To do this with BASH or Shell Script the elif operator ...

#33. Bash If语句 - 易百教程

在此示例中，通过比较两个字符串的值，简单演示了 if 语句的用法。 脚本文件：if-example2.sh #!/bin/bash # if condition is true if [ "yiibai" == "yiibai" ]; then ...

#34. 7.1. Introduction to if

At times you need to specify different courses of action to be taken in a shell script, depending on the success or failure of a command. The if construction ...

#35. 请问如何将if then fi 写成一行shell ? - 掘金

if [ "$?" -ne "0" ]; then echo "FAIL"; exit 1; else echo "SUCC"; fi ... Linux上的命令非常多，为了掌握它，很多同学耗尽了自己的脑细胞，憔悴了 ...

#36. Bash Script 語法解析. 各種單雙括弧、特殊符號語法 - Medium

“Bash Script 語法解析” is published by Vince in vswe. ... 建議把; do 或; then 和for, while, if 放在同一行! 遞增1~10 ... test.sh a b c#!/bin/bashecho $0 # .

#37. Linux shell條件判斷if中的-a到-z的意思【推薦】 - IT閱讀

這篇文章主要介紹了Linux shell條件判斷if中的-a到-z的意思,非常不錯，具有一定的參考借鑑價值，需要的朋友可以參考下.

#38. Linux shell中if [ $? -eq 0 ] 语句作用:判断命令是否执行成功

shell 脚本中$?是指上一次命令执行的成功或者失败的状态。如果成功就是0，失败为1.。语句if[$?eq0]是判断if语句的上一个命令执行如果成功就执行if中的 ...

#39. [shell] if else以及大于、小于、等于逻辑表达式[转]

本文也即《Learning the bash Shell》3rd Edition的第五章Flow Control之读书笔记，但我们将不限于此。flow control是任何编程语言中很常用的部分，也包括了bash。

#40. Unix / Linux Shell if...fi 语句- 蝴蝶教程

简述if...fi 语句是基本的控制语句，它允许Shell 有条件地做出决定和执行语句。 句法if [ expression ] then Statement(s) to be executed if expression is true fi ...

#41. linux(shell):if [[ ! ${file} =~ ^[0-9]+ ]] 求大神指教? - 慕课网

linux (shell):if [[ ! ${file} =~ ^[0-9]+ ]] 求大神指教? 首先我要声明一下，我在虚拟机里照 ...

#42. Linux篇：shell脚本中if的“-e，-d，-f” - 简书

Linux 篇：shell脚本中if的“-e，-d，-f” · 01 前言 · 02 文件表达式 · 03 整数变量表达式.

#43. The if-else condition in shell script - Educative.io

If -else is a very important coding concept. Just like other programming languages, shell script uses if-else statements to solve problems. If a condition is ...

#44. Shell Scripting - If & If/else - YouTube

HackerSploit here back again with another video, in this series we will be looking at how to create shell scripts.A shell script is a ...

#45. 一个语法一个Demo系列：Shell if else 基本用法

这个Demo 演示了shell 中if else 条件判断的用法。 if 条件判断一般格式为： if ... #!/bin/bash a=10 b=20 c=30 if [ $a -ne $b ];then echo "a is not equal to b" ...

#46. The Unix Shell's Humble If - Thoughtbot

To recap, we've seen that if in the Unix shell is both simple and complex. It does nothing but execute a command and branch based on exit status ...

#47. Using && in an IF statement in bash - DiskInternals

That is to say, if you're writing a bash script where two or more tests will have to return "True", then you have to use &&. Using && in an IF ...

#48. If, Else & If-Else Statements in Bash - Study.com

If Statement. When you write a shell script, you often need to make decisions and perform different sets of instructions for different decisions.

#49. 条件判断- Bash 脚本教程 - 网道- 互联网开发文档

否则，它们会被shell 解释为重定向操作符。 下面是一个示例。 #!/bin/bash ANSWER=maybe if [ -z "$ANSWER" ]; then echo "There is no answer." >&2 exit 1 fi if ...

#50. Shell 腳本的if-else/case 用法- 每日頭條

if -then 語句 if command then commands fi. if-then 的語法和我們熟悉的其他高級程式語言有些差別，以C++為例，if 後面一般是條件判斷表達式，通過 ...

#51. linux shell if判断字符串包含 - 我心飞扬

判断字符串包含 if [[ "${line}" =~ "substr" ]]; then echo "包含哦" fi. 这里好像得用 [[ ]] 才行, [ ] 可能会报错. 标签： linux shell.

#52. Bash IF - Syntax and Examples - Tutorial Kart

In the following example, we will compare numbers using if statement. Bash Shell Script #!/bin/bash # if condition (greater than) is true if [ 8 -gt 7 ]; then ...

#53. One line if/else condition in linux shell scripting - Stack Overflow

It looks as if you were on the right track. You just need to add the else statement after the ";" following the "then" statement.

#54. [轉載][Shell] if 條件式選項列表 - Jax 的工作紀錄

轉載自：利用test 指令的測試功能- 鳥哥的Linux 私房菜-- 學習Shell ... -r, 偵測該檔名是否存在且具有『可讀』的權限？ if[ -r $FILE ]; then.

#55. Linux If/elif/else/fi and case statement - 2020 - BogoToBogo

In this section, we'll see couple of examples of the 'if/elif/else' statement. Exampe #1: #!/bin/bash # b.sh if [ "$#" -gt 0 ] then echo "There are $# args!

#56. shell scripting if statement doesn't work - Unix Stack Exchange

It's important to remember that [ is a command, not a syntax feature (footnote 1), and that ] is the final argument to that command. In Bourne ( ...

#57. Bash Scripting: Nested if statement - LinuxConfig.org

An if statement in a Bash script is the most basic way to use a conditional statement. ... Software, Bash shell (installed by default).

#58. If-else — documentação Shell script 2021 - Mange@IFRN

If -else¶. Declaração if else para scripts em bash ou sh, há diversas formas diferentes. Tenha cuidado para não esquecer os espaços entre os colchetes.

#59. shell script 教學if case的用法 - 程式語言教學- 痞客邦

前往shell script教學目錄(1) 用if…fi來測試判斷式： (1-1) 其基本架構的寫法為： if [ 判斷式一] 邏輯運算符號[ 判斷式二] 邏輯運算符號[ 判斷式.

#60. Basic conditional branching with if-then statements

Basic syntax. To test the examples in this section, type the code into a shell script, and then execute it from the command-line. If ...

#61. Linux "if" Conditional Expressions - Burleson Consulting

Within an if statement, there may be multiple elif statements, each with their own conditional expression. The shell executes each one in order until the first ...

#62. Shell Scripting 101: If Else in Shell Script - LinuxForDevices

Shell Scripting 101: If Else in Shell Script · Basic if statement – if… [things to do if TRUE] …fi · if-else statement – if…[things to do if TRUE] ...

#63. 快速學會Shell Script - Jame's Blog

bin/bash # Welcome to the Interactive Shell . ... is your username" fi # 特別要注意的事 # 如果$Name 是空白的值，bash 會視為下面的指令 if [ !

#64. [Linux] Shell script 的if 用法簡介 - 雷射's zone - 痞客邦

稍微記一下shell script 的if 用法if [ -f /tmp/file.txt ]; then else fi -f : 檔案存在-d : 目錄存在-r : 執行此腳本的.

#65. 4 Bash If Statement Examples ( If then fi, If ... - The Geek Stuff

The ability to branch makes shell scripts powerful. In Bash, we have the following conditional statements: if..then..fi statement (Simple If) ...

#66. What does -z flag mean in shell script used in if condition

In both cases, the -z flag is a parameter to the bash's "test" built-in (a built-in is a command that is built-into the shell, ...

#67. Testing for various conditions in a shell script

Test - A Bourne Shell Programming / Scripting Tutorial for learning about using ... will not work; it is interpreted as if test$foo = "bar" ] , which is a ...

#68. Top Examples of If Else in Shell Scripting - eduCBA

“if-else” is dealing with two-part of the executions. If the “if-else “condition is “true” then the first group of statements will execute. If the condition is ...

#69. 簡明Linux Shell Script 入門教學

Shell Script 主要是使用在Linux 和MacOS 等Unix-like 作業系統的自動化 ... 在Shell Script 中同樣可以使用if..else 條件判斷，特別注意的是在Shell ...

#70. How To Check If File or Directory Exists in Bash - devconnected

When working with Bash and shell scripting, you might need to check whether a directory or a file exists or not on your filesystem.

#71. Control Program flow in Shell Scripts using if else and switch ...

Shell uses if to begin if else statement and fi to close it. Code: #!/bin/bash read -p "Enter username: " name if [ ...

#72. shell 将if、for、while写在一行 - FFing

shell 将if、for、while写在一行. 日常写if、for、while时，换行方便排查，但如果expect远端执行命令写在一行时则很方便。 if格式：（ if;then [命令] ...

#73. Decision-making using an if statement - Learning Linux Shell ...

The syntax is as follows: if (conditional-expression) action1 else action2 If the condition is true, … - Selection from Learning Linux Shell Scripting ...

#74. linux - How to test if a variable is equal to a number in shell

I know it is the if [ $Server_Name=1 ]; part. How do i fix it? linux · bash · shell · shell-script.

#75. linux shell中if else以及大于、小于、等于逻辑表达式介绍

在linux shell编程中，大多数情况下，可以使用测试命令来对条件进行测试，这里简单的介绍下，方便需要的朋友.

#76. linux shell if 參數- 台部落

linux shell if 參數. shell 編程中使用到得if語句內判斷參數. –b 當file存在並且是塊文件時返回真. -c ...

#77. linux shell if [[ ! -z $1 ]];是什么意思？ - 百度知道

linux shell if [[ ! ... -z 在if里的意思是空 ... 如果是命令，它就和参数组合为一体被shell 解释，那样比如">" "<" 就被shell 解释为重定向符号了。

#78. How To Script Error Free Bash If Statement? - Shell Tips!

The if in a Bash script is a shell keyword that is used to test conditions based on the exit status of a test command. An exit status of zero, and only zero, is ...

#79. Shell = Check if variable begins with - linux - Server Fault

Your original approach would work just fine if you escaped the hash: $ [[ '#snort' == \#* ]]; echo $? 0. Another approach would be slicing off the first ...

#80. Add "not" to if statement in shell script - Ask Ubuntu

“Not” is spelled ! , with no punctuation and a space after it. if ! id "$user_name" > /dev/null 2>&1 then echo 1>&2 "This user does NOT exists.

#81. Shell if else嵌套 - 嗨客网

在Shell 中，if 语句、elif 语句和else 语句可以进行任意的嵌套。 ... #!/bin/bash a=10 if (( $a>5 )) then if (( $a>20 )) then echo "a > 20" elif (( $a>10 ...

#82. Shell 脚本中的if 条件判断 - 知乎专栏

新建一个脚本文件[root@VM-0-5-centos ~]# vim file_test.sh #!/bin/bash read -p "please input filename: " filename if [ -e $filename ] then ...

#83. Bash Shell Scripting/Conditional Expressions - Wikibooks

Very often, we want to run a certain command only if a certain condition is met. For example, we might want to run the command cp source.txt destination.txt ...

#84. Shell判断语句· Linux 学习笔记 - 胡伟煌

if 语句通过关系运算符判断表达式的真假来决定执行哪个分支。Shell 有三种if ... else 语句：. if ... fi 语句；; if ... else ... fi 语句 ...

#85. 软件开发|Shell 脚本基础-使用if 语句进行条件检测 - Linux中国

Bourne Shell 的if 语句和大部分编程语言一样-检测条件是否真实，如果条件 ... bin/bash number=150 if then echo "Number is 150" fi if-else 语句: ...

#86. How to Use Conditional Statements in Bash Script - LinuxTechi

In a bash script, if statement checks whether a condition is true or not. If so, the shell executes the block of code associated with the if ...

#87. Bash/Dash Shell Script 當中的邏輯判斷 - $4 blog

首先是函式的例子： #!/bin/sh yes_func() { echo yes_func true } no_func() { echo no_func false } if ! yes_func || yes_func; then echo two ...

#88. Multiple conditions inside my if statement

I am using shell scripting and I am recieving odd results from my if statement ... #!/bin/bash L1=0 L2=1 if [[ $L1 -eq 0 ]] && [[ $L2 -eq 1 || $L2 -eq 2 ...

#89. Shell Script : if - 拉不拉多的夢幻世界

本文要來簡介shell script 中if else這個判斷式.這應該是最常用且最簡單的判斷式了以下用範例來說明#和string 去比對,如果條件成立,便會輸出Match 否則輸出No Mat.

#90. 那麼﹐kernel 又如何知道我們鍵盤輸入的東西 ... - Learning Linux

或許﹐許多人都已經聽過shell 或bash 這些名字﹐但不知道您是否知道它們 ... 您可以直接用test 命令﹐也可以用if 敘述﹐例如﹕test -f ~/test.sh 。

#91. Bash scripting cheatsheet - Devhints

Conditionals ; if [ ; "$string" ] ;; then ; echo "String is empty" ; elif [ ...

#92. Bash if else usage guide for absolute beginners - GoLinuxCloud

Beginners tutorial to learn bash if else statement in Linux and Unix. Nested if statement, Bash if multiple condition, if elif else statement with shell ...

#93. Install Linux on Windows with WSL - Microsoft Learn

Install Windows Subsystem for Linux with the command, wsl --install. ... The above command only works if WSL is not installed at all, if you ...

#94. Installing on Linux - Conda

Miniconda installer for Linux. ... bash Miniconda3-latest-Linux-x86_64.sh. Anaconda: ... If you are unsure about any setting, accept the defaults.

#95. Install and Set Up kubectl on Linux - Kubernetes

To find out, reload your shell and run type _init_completion . If the command succeeds, you're already set, otherwise add the following to ...

#96. nvm-sh/nvm: Node Version Manager - POSIX-compliant bash ...

Troubleshooting on Linux. On Linux, after running the install script, if you get nvm: command not found or see no feedback from your terminal after you ...

#97. subprocess — Subprocess management — Python 3.11.1 ...

Popen Constructor¶ · shell=True , the shell defaults to · /bin/sh . If args is a string, the string specifies the command to execute through the shell. This means ...

#98. Install Crouton

Just enter the following at the command line: sudo sh ~/Downloads/crouton -r list The Crouton installation will take roughly 15 minutes. If run with -f, ...

#99. Bash Pocket Reference Arnold Robbins , (2022)

... than if you run an executable shell script because in the latter case the argument with index 0 is the shell command used to invoke it as such i.