statements ;; esac 让我们看一个输入和判断操作系统的例子,脚本如下: #!/bin/bash echo "Which is Your Favorite Linux Distro?" echo "Debian, Ubuntu, SUSE, RHEL, Arch" read -p "Type Your Linux Distro:" OS case $OS in Debian) echo "Most Stable Linux OS, good choice " ;; Ubuntu) echo...
Increase readability of the if statements Let you use {} on larger complicated nested string blocks, provided those are for 3.0 and newer Version check I prefer awk and sed (core linux tools) approach to getting the version: run-shell 'tmux setenv -g TMUX_VERSION $(\ t...
if-else statements in Linux may not execute due to logical errors in the script. These errors may arise from incorrect logic in the if-else statements, such as using the wrong variables, referencing undefined variables, or making incorrect assumptions about the flow of the script. To troublesho...
if判断statements的最后一个的exit status,通常我们只放一个statement,如果为0,表示true,否则表示false。 执行下一条命令会冲掉原来exit status。可以使用$?来查看上一命令执行的结果。例如我们希望用一个新的cd命令来替代原来在linux kernel中已将编译的cd命令,由于function是优先于built-in命令,所以调用时,将调用我...
if(cond){ ... statements; ...}else{ ... statements; ...}可是有时候 cond 只在极少的情况下发生,例如:随机生成一个随机数,该随机数的范围是 0~100000,如果随机数小于 2,则将 val 赋值为 -1,否则将 val 赋值为当前UTC时间,相关C语言代码如下,请看: if(myrand() < 2) val = -1;else val ...
Conditions in bash scripting (if statements) - Linux Academy Blog https://linuxacademy.com/blog/linux/conditions-in-bash-scripting-if-statements/ Table of conditions The following table list the condition possibilities for both the single- and the double-bracket syntax. Save a single exception, th...
if condition then statements [elif condition then statements. ..] [else statements ] fi 1. 和C程序不一样,bash的判断不是通过boolean,而是通过statement,也就是执行命令后的最终状态(exit status)。所有的Linux命令,无论你是代码是C还是脚本,执行完,都返回一个整数通知他的调用这,这就是exit status,通常0...
If we were to convert the script above to a shell function to includeit in a larger program, we could replace the exit commands with return statementsand get the desired behavior: 类似地,通过带有一个整数参数的 return 命令,shell 函数可以返回一个退出状态。如果我们打算把上面的脚本转变为一个 ...
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for expression1 in iterable: for_suite else: else_suite Note:通常,expression或是一个单独的变量,或是一个变量序列,一般以元组的形式给出 如果以元组或列表用于expression,则其中的每个数据都会拆分表达式的项 D、编写循环的技巧 a. for循环比while循环执行速度快 ...