Afterdeclaring a string variable, use the-zoperator in anif statementto check whether a string is empty or not: MY_STRING="" if [ -z $MYSTRING ] then echo "String is empty" else echo "String is not empty" fi For more Shell scripting tips,check out or Bash/Shell scripting articles!
Let’s look at another option, “-z”, used so far in Bash to check for the empty string. The code has been started with Bash support, and we have initialized a string variable “v” with the value “Hello” in it. Then, we started the “if-else” statement to check whether the ...
-n operator -n is one of the supported bash string comparison operators used for checking null strings in a bash script. When -n operator is used, it returns true for every case, but that’s if the string contains characters. On the other hand, if the string is empty, it won’t ret...
Check empty bash array with string comparison We are going to use two elements to check if bash array is empty or not. One is${#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 ...
Run Bash Script MyScript.sh 1 2 3 ./MyScript.sh Output 1 2 3 No match found 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. He...
BashBites:Check Files Check a file exists 1 2 3 4 5 6 7 1. 2. 3. 4. 5. 6. 7. #!/bin/bashif [[ -e /tmp/adb.log ]]then echo "Exists"else echo "Not Exists"fi 1. Check Empty String 1 2 3 4 5 6 1. 2. 3.
Ambiguity in 'Not Found' Scenario: Because it returns -1 when the substring is not found, you'll need extra logic if you want to distinguish between different types of "no match" scenarios, such as an empty substring or a genuine non-match. 3. Using str.index() Method The str.index(...
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 ...
COMMAND /bin/bash -c "if [ -f ${CMAKE_BINARY_DIR}/cppcheck_failed ]; then echo 'Stopping build due to Cppcheck errors.'; exit 1; else echo 'No Cppcheck issues found. Continuing build.'; fi": 运行一个 Bash 脚本,检查 cppcheck_failed 文件是否存在。如果存在,则终止构建并输出错误消息...
You can use the "mount" command to check if a directory is mounted on a Linux system. For example, to check if the directory "/mnt/data" is mounted, you can run ? mount | grep "/mnt/data" If the directory is mounted, the command will return information about the mount point, ...