Is there any difference between $@ and "$@"? [duplicate]

Question

Is there any difference between $@ and "$@"?

I understand there may be differences for non special characters, but what about the @ sign with input arguments?

Answer 1

Passing $@ to a command passes all arguments to the command. If an argument contains a space the command would see that argument as two separate ones.

Passing "$@" to a command passes all arguments as quoted strings to the command. The command will see an argument containing whitespace as a single argument containing whitespace.

To easily visualize the difference write a function that prints all its arguments in a loop, one at a time:

#!/bin/bash

loop_print() {
    while [[ $# -gt 0 ]]; do
        echo "argument: '$1'"
        shift
    done
}

echo "#### testing with \$@ ####"
loop_print $@
echo "#### testing with \"\$@\" ####"
loop_print "$@"

Calling that script with

<script> "foo bar"

will produce the output

#### testing with $@ ####
argument: 'foo'
argument: 'bar'
#### testing with "$@" ####
argument: 'foo bar'