shell $*,$@,$#的区别详解

$*：如果加" ",即"$*"则表示视所有该命令参数为一个单词，如果没有" ",那么该命令每一个参数

都视为独立的参数。比如传入的参数：1 2 3 4，$*：表示1 2 3 4；"$*"：表示1,2,3,4；

$@：不管有" "没有" "，每个参数都是独立的，但是，如果传入的参数比如是：1 "2 3" 4，那就有点差异了，"$@": 表示1,2  3,4；而$@：表示1,2,3,4；

$#：表示参数个数。

例子：

[yangzheng@localhost shell_test]$ cat test.sh 

echo
index=1


echo "Listing args with\"\$*\":"


for arg in "$*"
do
    echo "Arg #$index=$arg"
    let "index+=1"
done


echo "All the parameters is considered to be a word."


echo "==========================================================="
echo
index=1


echo "Listing arg with\"\$@\":"


for arg in "$@"
do
    echo "Arg #$index=$arg"
    let "index+=1"
done


echo "All the parameters is considered to be separated words"


echo "==========================================================="
echo
index=1


echo "Listing arg with \$*:"


for arg in $*
do
    echo "Arg #$index=$arg"
    let "index+=1"
done


echo "All the parameters is considered to be separated words"


echo "==========================================================="
echo
index=1


echo "Listing arg with \$@:"


for arg in $@
do
    echo "Arg #$index=$arg"
    let "index+=1"
done


echo "All the parameters is considered to be separated words"


echo "==========================================================="
echo
index=1


echo "Listing arg with \$#:"


for arg in $#
do
    echo "Arg #$index=$arg"
    let "index+=1"
done


echo "echo params"

[yangzheng@localhost shell_test]$ 

[yangzheng@localhost shell_test]$ sh test.sh 1 2 3 4 


Listing args with"$*":
Arg #1=1 2 3 4
All the parameters is considered to be a word.
===========================================================


Listing arg with"$@":
Arg #1=1
Arg #2=2
Arg #3=3
Arg #4=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $*:
Arg #1=1
Arg #2=2
Arg #3=3
Arg #4=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $@:
Arg #1=1
Arg #2=2
Arg #3=3
Arg #4=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $#:
Arg #1=4
echo params
[yangzheng@localhost shell_test]$ sh test.sh 1 “?”
[yangzheng@localhost shell_test]$ sh test.sh 1 "2 3" 4


Listing args with"$*":
Arg #1=1 2 3 4
All the parameters is considered to be a word.
===========================================================


Listing arg with"$@":
Arg #1=1
Arg #2=2 3
Arg #3=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $*:
Arg #1=1
Arg #2=2
Arg #3=3
Arg #4=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $@:
Arg #1=1
Arg #2=2
Arg #3=3
Arg #4=4
All the parameters is considered to be separated words
===========================================================


Listing arg with $#:
Arg #1=3
echo params
[yangzheng@localhost shell_test]$