在BASH脚本中,if with or语句和elif语句都是用于条件判断的控制结构,但它们的使用场景和逻辑有所不同。 if with or 语句 if with or语句允许你在一个if条件中检查多个条件,只要其中一个条件为真,整个表达式就为真。这通常通过逻辑运算符||(OR)来实现。 基础概念: ||是逻辑 OR 运算符,用于连接两个或多...
The pattern will match if it matches any part of the string. Anchor the pattern using the ‘^’ and ‘$’ regular expression operators to force it to match the entire string. The array variable BASH_REMATCH records which parts of the string matched the pattern. The element of BASH_REMATC...
if [ -z ${var+x} ]; then echo "var is unset"; else echo "var is set to '$var'"; fi 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 sw...
Bash, short for "Bourne Again SHell," is a powerful scripting language used in Unix-based operating systems. One of the fundamental constructs in Bash programming is the if statement. The if statement allows you to control the flow of your script based on specific conditions. In this article,...
name=jerry,name:2结果为rryname:2结果为rry{variable:pos:num}: 偏移pos个字符,取num个字符长度的子串 name=‘hello world’, ${name:2:5}结果为“llo w” 字符串处理,将来在bash中经常用的 bash能力分为三个最为重要: 字符串能力 grep,awk,sed ...
if [ $# -eq 0 ] ; then printf “%s\n” “Type--help for help.” exit 192 fi # Process the parameters while [ $# -gt 0 ] ; do case “$1” in -h | --help) # Show help printf “%s\n” “usage:$SCRIPT [-h][--help] -c companyid” ...
Use the if-else statement with the -v option to check if an environment variable is set in bash. The echo command in the if block will be executed if the will
$ type -t if keyword 上面例子中,bash是文件,if是关键词。 快捷键 Bash 提供很多快捷键,可以大大方便操作。下面是一些最常用的快捷键,完整的介绍参见《行操作》一章。 Ctrl + L:清除屏幕并将当前行移到页面顶部。 Ctrl + C:中止当前正在执行的命令。
location"# Notice that the space in the $location variable is ignored and the location argument accepts the entire string as the value 在JSON 字典输出中,查看已创建的资源组的属性。 使用If Then Else 确定变量是否为 null 若要评估字符串,请使用!=,要评估数字,请使用-ne。 以下 If Then Else 语句...
-z STRING True if string is empty. -n STRING STRING True if string is not empty. 即,test命令使用-z STRING操作符来判断STRING字符串的长度是否为 0。 如果为 0,就是空字符串,会返回 true。 具体写法是test -z STRING,使用[命令则写为[ -z STRING ]。