上面那种常规方法,写法比较麻烦,所以set -e 参数解决了这一烦恼 #!/usr/bash set -e var echo "hello world" 执行上面脚本,结果如下 test: line 5: var: command not found set +e 取消 #!/usr/bash set -e set +e var echo "hello world" 执行上面脚本,结果如下 test
/bin/bashecho${var:-"Variable is not set"} ---> Variable is not setecho"1 - Value of var is ${var}" ---> 1- Value of var isecho${var:="Variable is not set"} --->Variable is not set 同时var已经被赋值为Variable is not setecho"2 - Value of var is ${var}" --->2 -...
# 取消变量的值 unset my_variable 还可以使用环境变量为变量赋值。例如,可以使用$PATH环境变量: 代码语言:txt 复制 # 使用环境变量为变量赋值 current_path=$PATH echo "当前的PATH环境变量值为:$current_path" 参考链接: Bash变量赋值 相关搜索: linux bash 变量赋值 在bash中赋值位置变量 如何为bash中的布尔值...
参考:https://stackoverflow.com/questions/3601515/how-to-check-if-a-variable-is-set-in-bash 6、换算秒为分钟、小时 代码语言:javascript 代码运行次数:0 运行 AI代码解释 #!/bin/bash a=60100 swap_seconds () { SEC=$1 (( SEC < 60 )) && echo -e "持续时间: $SEC秒\c" (( SEC >= 60...
-bash: a: command not found 看来这样子行不通。Bash中声明一个变量需要用到Bash内置命令declare,演示如下 点击查看代码 [ken@Dell-Desktop ~]$declare b [ken@Dell-Desktop ~]$echo$b[ken@Dell-Desktop ~]$declare b2=3[ken@Dell-Desktop ~]$echo$b23 ...
command, not just those that precede thecommandname.-mJob control is enabled.-nRead commands butdonot execute them.-ooption-name Set the variable corresponding to option-name: allexport same as-abraceexpand same as-Bemacs use an emacs-style line editing interface ...
if [[ "$INT" =~ ^-?[0-9]+$ ]]; wangdoc.com/bash/condit • AND运算:符号&&,也可使用参数-a。 • OR运算:符号||,也可使用参数-o。 • NOT运算:符号!。 [[ $INT -ge $MIN_VAL && $INT -le $MAX_VAL ]] ((...))作为算术条件 if ((3 > 2)); then if关键字后面 命令的...
if [[ $var != *sub_string* ]]; then printf '%s\n' "sub_string is not in var." fi # 也可以在数组中运行 if [[ ${arr[*]} == *sub_string* ]]; then printf '%s\n' "sub_string is in array." fi使用case语句:case "$var" in *sub_string*) # Do stuff ;; *sub_string2...
is a ! or a ^ then any character not enclosed is matched. The sorting order of characters in range expressions is determined by the current locale and the value of the LC_COLLATE shell variable, if set. A - may be matched by including it as the first or last character in the set. ...
ShellCheck will warn when using features not supported by the shebang. For example, if you set the shebang to#!/bin/sh, ShellCheck will warn about portability issues similar tocheckbashisms: echo{1..$n}# Works in ksh, but not bash/dash/shecho{1..10}# Works in ksh and bash, but ...