#!/bin/bash # Set the variable variable="" # Check if the variable is empty if [ -z "$variable" ]; then echo "Variable is empty." else echo "Variable is not empty." fi Copy Save changes and exit from the nano t
如果变量var为空,则输出“Variable is empty”,否则输出“Variable is not empty”。 除了判断变量是否为空外,有时候我们还需要判断一个变量是否被定义。在bash中,我们可以使用另外一个条件判断来实现: ```bash if [ -z ${var+x} ]; then echo "Variable is not defined" else echo "Variable is defined"...
如果变量为空,那么会输出"Variable is empty";否则,会输出"Variable is not empty"。 除了使用-z参数外,我们还可以使用其他参数来判断变量是否为空。例如,-n参数可以判断变量是否不为空。示例代码如下: ```bash if [ -n $variable ]; then echo "Variable is not empty" else echo "Variable is empty" f...
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!
Check if Command Exists in Bash What is awk print $1? find file by name in linux Check If Variable Is Empty in Bash Add Comma to End of Each Line in Bash Bash for Loop 1 to 10 What is echo $1 in Bash sed Replace String in File Bash Log Output to File Bash Get Absolute Path ...
The weather is hot. 使用case语句 当有时多个if的语句造成阅读困难的时候,可以使用case来替换多个if。case的语法结构如下: case 'variable' in 'pattern1' ) Command … ;; 'pattern2' ) Command … ;; 'pattern3' ) Command … ;; esac 注意 ...
If the $count variable is zero, the grep output was empty, passed to the wc-1 because the pattern was not matched. The script then outputs the message No match found. to the console using the echo command. That’s all about Bash check if grep result is empty. Was this post helpful?
关于bash中if语法结构的广泛误解 Linux 技巧:Bash的测试和比较函数(探密test,[,[[,((和if-then-else) if语法[Linux(bash_shell)] http://blog.csdn.net/ycl810921/article/details/4988778 1: 定义变量时, =号的两边不可以留空格. eg: gender=femal---right gender =femal-...
bash 中的条件语句，基础就是 Test 。 if 先来个实例： x=5; if [ $x = 5 ]; then e...
case variable in pattern1) command1 ;; pattern2) command2 ;; … esac “` 这样,可以更清晰地对多个条件进行判断和处理。 评论 if命令是Linux系统中的一个条件控制命令,用于根据给定的条件来进行判断和执行不同的操作。if命令通常与then结合使用,结构如下所示: ...