```bash if [ -z $variable ]; then echo "Variable is empty" else echo "Variable is not empty" fi ``` 在这段代码中,-z参数用于判断变量$variable是否为空。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...
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 ${var+x} ]; then echo "Variable is not defined" else echo "Variable is defined"...
In this method, I will be using the-nflag to check whether the variable is empty or not. Here's the simple script which will tell me whether the variable is empty or non-empty: #!/bin/bash variable="" if [ -n "$variable" ]; then echo "Variable is not empty." else echo "Vari...
bash command if a string is not empty examples of the check when DiskInternals can help you Are you ready? Let's read! Variables that are set and not empty A variable is either defined or not defined. However, when a variable is defined but has no value, then the variable is “Not ...
$ bash ifnot.sh Example 3 Let’s try the “if-not” operator to check a different condition this time. This time, we have been using the “-z” operator to check whether the variable is empty or not. For this, we have started the code with the initialization of an empty variable ...
if条件判断用于根据不同的条件执行不同的命令或代码块。 二、变量判断的常见形式 数值比较 -eq:等于 -ne:不等于 -gt:大于 -lt:小于 -ge:大于等于 -le:小于等于 示例: 代码语言:txt 复制 num=5 if [ $num -gt 3 ]; then echo "数字大于 3" else echo "数字小于等于 3" fi ...
The weather is nice. sean@debian-12:~$ ./weather.sh 30 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 ...
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---wrong gender= femal---wrong 2 条件测试语句 [ 符号的两边都要留空格.
/bin/bash str=”hello” if [ -z “$str” ] then echo “String is empty.” else echo “String is not empty.” fi “` 在这个例子中,使用了-z选项来判断字符串$str是否为空。如果字符串为空,则输出”String is empty.”,否则输出”String is not empty.”。
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...