Afterdeclaring a string variable, use the-zoperator in anif statementto check whether a string is empty or not: MY_STRING="" if [ -z $MYSTRING ] then echo "String is empty" else echo "String is not empty" fi For more Shell scripting tips,check out or Bash/Shell scripting articles!
Here is another option, “-n”, to check whether the specified string is empty or not. It works on the rule of checking the length of a string by counting the string characters in it. If the length of a particular string turns out to be other than zero, it will return “true”; o...
In this tutorial you'll learn how to compare strings in bash shell scripts.You'll also learn to check if a string is empty or null. Jun 7, 2024—Abhishek Prakash How to Compare Strings in Bash Shell Scripting Dealing with strings is part of any programming language. Bash shell scripting ...
Check empty bash array with string comparison We are going to use two elements to check if bash array is empty or not. One is${#array[@]}and other is the-zoperator. Here, the${#array[@]}is used in Bash for array expansion, allowing you to access all elements of an array.Don't ...
In this example, the substitution command is used with $() to capture the output of grep, and then the -z option of the test command is used to check if the resulting string is empty or not. Here, the grep command searches for the pattern pattern in the file dummy.txt. The output...
In both examples, we used the if statement with the -z option to check if the variable is empty. Here, the -z option is a unary test operator that checks if the string is empty. This operator accepts one argument that is a string to be tested; it returns true (0 exist status) if...
-z is the second supported bash string comparison operator used to check if a string is empty or not. The -z operator functions similarly like -n operator. Below is an example: Most importantly, you should add spaces around the square brackets. If there are no spaces, bash will complain ...
# Define a string input_str="" # Check if the string is empty if [ -z "$input_str" ]; then echo "The string is empty" else echo "The string is not empty" fi Output: The string is empty Explanation: In the exercise above, ...
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...
One of the most common operations when working with strings in Bash is to determine whether or not a string contains another string. In this article, we will show you several ways to check if a string contains a substring.