A summary for some important Bash scripts
| Command
|
Description
|
| set
|
set [options] [arguments][1]
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.
|
Reference