Bash script

A summary for some important Bash scripts

Command

Description

set

set [options] [arguments] sign (-) is used with the command’s option to enable that option and the plus sign (+) is used with the command’s option to disable that option -a It defines those variables or functions which are created or modified or exported Example, These variables v1 and v2 can be accessed after executing the script #!/bin/bash #Enable -a option to read the values of the variables set -a #Initialize three variables v1=78 v2=50 -b It informs the job termination. -B To do the task of the brace expansion. -C It disables the overwriting feature of the existing file Example, $ cat > testfile.txt $ set -C $ cat > testfile.txt. # Could not overwrite testfile.txt -e It exits for non-zero exit status value. -f It disables the filename generation task. -h It saves the location of the command where it has been used. -m It enables job control. -n It reads the commands. -t It exits from the command after executing a single command. -u It traces the unset variables - error is printed for the uninitialized variable -v It prints the shell input lines. -x It displays the commands and their attributes sequentially. It is mainly used to debug the script. -- variable The string value is divided into three parts based on the space that is printed #!/bin/bash #Define a string variable myvar="Learn bash programming" #Set the set command without option and with variable set -- $myvar #Print the split value printf "$1\n$2\n$3\n" Exit Values of Set Command Zero (0) is returned to complete the task successfully. One (1) is returned if a failure occurs for any invalid argument. One (1) is returned if a failure occurs for a missing argument.