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 "$variable" ]; then echo "Variable is not empty." else echo "Vari...
So in our case, since variable was initialized with the value of 10, which is a non-zero string, the script will print The variable is not empty to the console. Use = Operator Use = operator to check if the specified variable is empty or not. Use = Operator 1 2 3 4 5 6 7 8...
Check to see if a variable is empty or not Create a new bash file, named, and enter the script below. The script above stores the first command-line argument in a variable and then tests the argument in the next statement. This script will print the first argument because it is not em...
- Testifa given variable is [eq]ual/[n]ot [e]qual/[g]reater [t]han/[l]ess [t]han/[g]reater than or [e]qual/[l]ess than or [e]qual to the specified number: [[$variable-eq|ne|gt|lt|ge|leinteger]] - Testifthe specified variable has a [n]on-empty value: [[ -n$vari...
If the $count variable is zero, the grep output was empty, passed to the wc-1 because the pattern was not matched. The script then outputs the message No match found. to the console using the echo command. That’s all about Bash check if grep result is empty. Was this post helpful?
其次,Shell 是一个命令解释器,解释用户输入的命令。它支持变量、条件判断、循环操作等语法,所以用户可以用 Shell 命令写出各种小程序,又称为脚本(script)。这些脚本都通过 Shell 的解释执行,而不通过编译。 最后,Shell 是一个工具箱,提供了各种小工具,供用户方便地使用操作系统的功能。
For those that are looking to check if a variable is unset or empty in script running with set -u: if [ -z "${var-}" ]; then echo "Must provide var environment variable. Exiting..." exit 1 fi The regular [ -z "$var" ] check will fail with var; unbound variable if set -...
Adding one or two directories to PATH variable in linux ( Using Bash script) 0 Detect empty input arg in bash script 401 Are there any standard exit status codes in Linux? 226 How do I find the number of arguments passed to a Bash script? 198 Checking for the correct number of argu...
The string is empty Explanation: In the exercise above, The variable 'input_str' is defined as an empty string. An if statement checks if the length of '$input_str' is zero using the -z test operator. If the string is empty, the script prints "The string is empty" using the "echo...
- Test if the specified variable has an empty value: [[ -z $variable ]] - Test if the specified [f]ile exists: [[ -f path/to/file ]] - Test if the specified [d]irectory exists: [[ -d path/to/directory ]] - Test if the specified file or directory [e]xists: ...