Special $@ and $* Parameters in bash

#bash #gnulinux #linux

There is a say no difference between $@ and $* in Shell! What ?!!

Have you ever thought if there is no difference, why there are two of them? it could be one $@ or $* , Do You Agree?

So Let’s see What the difference is . Create a script and try it one by one

First One $@ :

#! /bin/bash 

MAIN()
{
        echo "First Parameter is $1"
}

MAIN $@

Execute it like below and give the script some arguments:

$ ./Diff.sh "Jhon Smith" "Marry Ann" 
$ First Parameter is Jhon

Second One $* :

#! /bin/bash 

MAIN()
{
        echo "First Parameter is $1"
}

MAIN $*

The result will be :

$ ./Diff.sh "Jhon Smith" "Marry Ann" 
$ First Parameter is Jhon

Far Now There is no difference, maybe those people were right!

Let us go further and try them with double quotes "$@" :

#! /bin/bash 

MAIN()
{
        echo "First Parameter is $1"
}

MAIN "$@"

$ ./Diff.sh "Jhon Smith" "Marry Ann" 
$ First Parameter is Jhon Smith

The second one in double quotes "$*" :

#! /bin/bash 

MAIN()
{
        echo "First Parameter is $1"
}

MAIN "$*"

$ ./Diff.sh "Jhon Smith" "Marry Ann" 
$ First Parameter is Jhon Smith Marry Ann

So be careful when you use double quotes and tell those people there is a difference, explain to them shell is sensitive to double quotes.

Resources

Double Quotes are necessary.