Linux几个变量

linux shell中部分变量的含义

$0：脚本名

$1：传给脚本的第一个参数

$2：传给脚本的第二个参数

$$：脚本运行的PID

$@：传给脚本的所有参数列表（list形式）

$*：传给脚本的所有参数列表（字符串形式）

$#：传给脚本的参数个数

$?：上个已执行命令的退出状态码，成功为0

示例：

#!/bin/bash
# test linux variables
# 20181224 by kyle

# 使用basename获取脚本名，避免输出脚本名时候带上命令:./test1.sh
name=$(basename $0)

echo 
echo "number of variables is：$#"
echo "the first variable is: $1"
echo "the second is: $2"
echo "the scrip's name is: $name"
echo "the script's PID is: $$"
echo "the parameters are: $@"
echo "the parameter list is: $*"
echo "show script stat: $?"
echo

执行结果：

[root@localhost mountTest]# ./VariablesTest.sh 

number of variables is：0
the first variable is: 
the second is: 
the scrip's name is: VariablesTest.sh
the script's PID is: 4829
the parameters are: 
the parameter list is: 
show script stat: 0

*比较“$@”和“$”

#!/bin/bash
# compare $@ with $*
# 20181224 by kyle

echo 
echo "followed by \$*"
count=1
#
for param in "$*"
do
  echo "\$* Parameter #$count = $param"
  count=$[ $count + 1 ]
done
#

echo 
echo "Here is \$@"
count=1
#

for param in "$@"
do
  echo "\$@ Parameter #$count = $param"
  count=$[ $count + 1 ]
done

执行结果：

[root@localhost mountTest]# ./ShellTest.sh 1 2 3 4 5 

followed by $*
$* Parameter #1 = 1 2 3 4 5

Here is $@
$@ Parameter #1 = 1
$@ Parameter #2 = 2
$@ Parameter #3 = 3
$@ Parameter #4 = 4
$@ Parameter #5 = 5