Afterdeclaring a string variable, use the-zoperator in anif statementto check whether a string is empty or not: MY_STRING="" if [ -z $MYSTRING ] then echo "String is empty" else echo "String is not empty" fi For more Shell scripting tips,check out or Bash/Shell scripting articles!
This way, to test if a number, n, is prime for numbers greater than 3, we perform a series of steps: check if n is divisible by 2 or 3 check if n is divisible by numbers of the form 6k-1 or 6k+1 that are less than or equal to the square root of n If n satisfies neither...
Using the “If -Z” Statement Sometimes, it is required to check if a string variable is empty or if it contains a string of zero length. There are many options in Bash to do this task. Using the “-z” option with the “if” statement is one of the ways to check whether a vari...
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...
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在脚本中,if语句的不同部分通常是良好分隔的。以下是一些简单的例子: 7.1.1.3. 检查文件 第一个例子检查一个文件是否存在: anny ~> msgcheck.shanny ~> 7.1.1.4. 检查shell选项 加入到你的Bash配置文件中去: # These lines will print a message if the noclobber option is set: ...
在Bash/Shell脚本中,可以使用特殊字符"\n"来表示换行符。当需要在变量中插入换行符时,可以使用以下方法: 1. 使用双引号(")包裹字符串,并在需要插入换行符的位置使用"\n"。例如: `...
I have had so many instances where I wanted to check if a value was present in an array or not. You can probably iterate over all the array items and check it individually, but what if I give you the red pill? I have created an array in which there is a stringasdfand I want to...
echo "The number is odd." fi else echo "The number is not positive." fi Conclusion The Bash if statement is a fundamental construct that allows you to control the flow of your scripts based on specific conditions. By leveraging conditionals, such as numeric and string comparisons, and file...