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Difference between $@ and $*

When in double quotes:

• "$@" expands to "$1" "$2" "$3" ...
• "$*" expands to "$1c$2c$3c..." (where c is the first character in IFS or space)

When unquoted, they behave really the same in practical cases.

• Treat $@ as an array of strings
• Treat $* as a single concatenated string

---

Consider the following script:

# bar.sh
echo "Arg 1: $1"
echo "Arg 2: $2"
echo "Arg 3: $3"
echo

and

# foo.sh
echo '$* without quotes:'
./bar.sh $*

echo '$@ without quotes:'
./bar.sh $@

echo '$* with quotes:'
./bar.sh "$*"

echo '$@ with quotes:'
./bar.sh "$@"

$ ./foo.sh arg1 "arg21 arg22" arg3
$* without quotes:            
Arg 1: arg1
Arg 2: arg21
Arg 3: arg22

$@ without quotes:
Arg 1: arg1
Arg 2: arg21
Arg 3: arg22

$* with quotes:
Arg 1: arg1 arg21 arg22 arg3
Arg 2:
Arg 3:

$@ with quotes:
Arg 1: arg1
Arg 2: arg21 arg22
Arg 3: arg3

---

• "$*" ignores quotes in the argument list,
• "$*" treats the whole argument list as a single concatenated string

and

• "$@" treats quoted arguments to be a single argument
• "$@" is an array of strings

---

Reference:

• man bash
• https://stackoverflow.com/a/22589064/2827680

Tags:

#literature-note #scripting #syntax

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