:特殊變量列表
- $0 當(dāng)前腳本的文件名
- $n 傳遞給腳本或函數(shù)的參數(shù)。n 是一個(gè)數(shù)字团甲，表示第幾個(gè)參數(shù)馅而。例如祥诽，第一個(gè)參數(shù)是$1，第二個(gè)參數(shù)是$2用爪。
- $# 傳遞給腳本或函數(shù)的參數(shù)個(gè)數(shù)
- $* 傳遞給腳本或函數(shù)的所有參數(shù)原押。
- $@ 傳遞給腳本或函數(shù)的所有參數(shù)。被雙引號(hào)(" ")包含時(shí)偎血，與 $* 稍有不同
- $? 上個(gè)命令的退出狀態(tài)诸衔，或函數(shù)的返回值盯漂。
- $$ 當(dāng)前Shell進(jìn)程ID。對(duì)于 Shell 腳本笨农，就是這些腳本所在的進(jìn)程ID就缆。
腳本：
#!/usr/bin/env sh
echo "pid" " " "\$\$ -> $$"
echo "filename" " " "\$0 -> $0"
echo "param1" " " "\$1 -> $1"
echo "param2" " " "\$2 -> $2"
echo "allparams" " " "\$* -> $*"
echo "allparams" " " "\$@ -> $*"
echo "totalparams" " " "\$# -> $#"
運(yùn)行命令:
./test p1 p2 p3
運(yùn)行結(jié)果:
pid $$ -> 717
filename $0 -> ./test.sh
param1 $1 -> p1
param2 $2 -> p2
allparams $* -> p1 p2 p3
allparams $@ -> p1 p2 p3
totalparams $# -> 3
$* $@區(qū)別
$* 和 $@ 都表示傳遞給函數(shù)或腳本的所有參數(shù)，不被雙引號(hào)(" ")包含時(shí)谒亦，都以"$1" "$2" … "$n" 的形式輸出所有參數(shù)竭宰。
但是當(dāng)它們被雙引號(hào)(" ")包含時(shí)，"$*" 會(huì)將所有的參數(shù)作為一個(gè)整體份招，以"$1 $2 … $n"的形式輸出所有參數(shù)切揭；"$@" 會(huì)將各個(gè)參數(shù)分開，以"$1" "$2" … "$n" 的形式輸出所有參數(shù)锁摔。
#!/usr/bin/env sh
echo "\$*=" $*
echo "\"\$*\"=" "$*"
echo "\$@=" $@
echo "\"\$@\"=" "$@"
echo "print each param from \$*"
for var in $*
do
echo "$var"
done
echo "print each param from \$@"
for var in $@
do
echo "$var"
done
echo "print each param from \"\$*\""
for var in "$*"
do
echo "$var"
done
echo "print each param from \"\$@\""
for var in "$@"
do
echo "$var"
done
./test a b c d
$*= a b c d
"$*"= a b c d
$@= a b c d
"$@"= a b c d
print each param from $*
a
b
c
d
print each param from $@
a
b
c
d
print each param from "$*"
a b c d
print each param from "$@"
a
b
c
d
