在这个示例中,$variable是要检查的变量。如果它为空,则打印"Variable is empty";否则,打印"Variable is not empty"。 使用双引号和等号 另一种常见的方法是使用双引号和等号进行比较。 以下是示例代码: if["$variable"=""];thenecho"Variable is empty"elseecho"Variable is not empty"fi 在这个示例中,$vari...
if[!-z"$variable"];thenecho"Variable is not empty"elseecho"Variable is empty"fi 在这个示例中,$variable是要检查的变量。如果它不为空,则打印"Variable is not empty";否则,打印"Variable is empty"。 使用条件表达式检查变量是否为空 除了if 语句,还可以使用条件表达式来检查变量是否为空。条件表达式可以...
Checking If Variable Is Empty in Bash There are multiple ways to check if a variable is empty or not. Before moving towards those methods, knowing when a variable is called empty is necessary. In Bash, a variable is called empty if: A variable is declared without assigning any value to ...
Bash has a few conditional expressions, of which you can use one to check if a variable is empty or not. That is the-zoperator. Using the-zoperator followed by a variable will result in trueif the variable is empty. The condition will evaluate to false if the variable is not empty. ...
3. By comparing a variable to an empty string As the name suggests, in this method, I will be comparing the variable to an empty string using the[]operator. Here's the simple script: #!/bin/bash if [ "$variable" = "" ]; then echo "Variable is empty." else echo "Variable is ...
function empty { local var="$1" # Return true if: # 1. var is a null string ("" as empty string) # 2. a non set variable is passed # 3. a declared variable or array but without a value is passed # 4. an empty array is passed if test -z"$var" then [[ $( echo"1" ...
常见$(variable) 3 初始化数组 array=(a b c d) 接下来是一个demo,内含详细注释 #!/bin/bash # 单方括号内可以使用变量 SWAP_DEVICE=/dev/sda1 if [ ${SWAP_DEVICE} == "/dev/sda1" ]; then echo "单方括号内可以使用变量" fi # 双方括号内可以使用变量 ...
If you want to see if a variable is empty, you can use the-zflag instead of comparing. The-zflag checks if the length of the variable is zero, and it returnstrueif it is zero. Command: #!/bin/bashstr=if[-z$str];thenecho"It is empty string"fi ...
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 ...
TestFile1 does not exist or is empty. 现在创建一个空文件用来测试: [student@studentvm1 testdir]$ File="TestFile1" ; touch $File ; if [ -s $File ] ; then echo "$File exists and contains data." ; else echo "$File does not exist or is empty." ; fi ...