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Difference between $* and $@

Posted by Mohammed in Shell on March 12, 2008 | one response

Run the script below and feel the difference ;)

shell]$ cat input
#! /bin/bash

echo "$# inputs"
echo ""
echo '"$@" output'
for arg in "$@"; do
echo $arg
done
echo ""
echo '$@ output'
for arg in $@; do
echo $arg
done
echo ""
echo '"$*" output'
for arg in "$*"; do
echo $arg
done
echo ""
echo '$* output'
for arg in $*; do
echo $arg
done
shell]$ ./input a b 'c d'
3 inputs

"$@" output
a
b
c d

$@ output
a
b
c
d

"$*" output
a b c d

$* output
a
b
c
d
shell]$

One Response to “Difference between $* and $@”

  1. mohammed says:
    February 6, 2010 at 10:53 am

    You can find the following explanation under “Special Parameters” in the man page for BASH.

    * Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, it expands to a single word with the value of each parameter separated by the first character of the IFS special variable. That is, “$*” is equivalent to “$1c$2c…”, where c is the first character of the value of the IFS variable. If IFS is unset, the parameters are separated by spaces. If IFS is null, the parameters are joined without intervening separators.

    @ Expands to the positional parameters, starting from one. When the expansion occurs within double quotes, each parameter expands to a separate word. That is, “$@” is equivalent to “$1″ “$2″ … If the double-quoted expansion occurs within a word, the expansion of the first parameter is joined with the beginning part of the original word, and the expansion of the last parameter is joined with the last part of the original word. When there are no positional parameters, “$@” and $@ expand to nothing (i.e., they are removed).

    ~mohammed

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