shell中的函数与数组

Posted 2020-10-31

shell中的函数

1.第一个案例：

[[email protected] shell]# sh fun1.sh 
the first par is b
the second par is a
the third par is 2
the script name is fun1.sh
the number of par is 5
[[email protected] shell]# cat fun1.sh 
#!/bin/bash
function inp(){
    echo "the first par is $1"
    echo "the second par is $2"
    echo "the third par is $3"
    echo "the script name is $0"
    echo "the number of par is $#"
}

inp b a 2 3 adf

也可以把参数放在外面

[[email protected] shell]# cat fun1.sh 
#!/bin/bash
function inp(){
    echo "the first par is $1"
    echo "the second par is $2"
    echo "the third par is $3"
    echo "the script name is $0"
    echo "the number of par is $#"
}

inp $1 $2 $3 

[[email protected] shell]# sh fun1.sh 1 2
the first par is 1
the second par is 2
the third par is 
the script name is fun1.sh
the number of par is 2

2.第二个案例：

[[email protected] shell]# cat fun2.sh 
#!/bin/bash
sum(){
    s=$[$1+$2]
    echo $s
}

sum 1 10
[[email protected] shell]# sh fun2.sh 
11
[[email protected] shell]# sh -x fun2.sh 
+ sum 1 10
+ s=11
+ echo 11
11

3.第三个案例：

[[email protected] shell]# cat fun3.sh 
#!/bin/bash
ip()
{
    ifconfig |grep -A1 "$1: "|awk ‘/inet/ {print $2}‘
}

read -p "please input the eth name: " eth
ip $eth 
[[email protected] shell]# sh fun3.sh 
please input the eth name: ens33
192.168.188.130
[[email protected] shell]# sh fun3.sh 
please input the eth name: ens33:0
192.168.188.150
[[email protected] shell]# sh fun3.sh 
please input the eth name: ens37
192.168.252.128

shell中的数组

1.定义数组并打印：

[[email protected] shell]# b=(1 2 3)
[[email protected] shell]# echo $b
1
[[email protected] shell]# echo ${b[@]}
1 2 3
[[email protected] shell]# echo ${b[*]}
1 2 3
[[email protected] shell]# echo ${b[1]}
2
[[email protected] shell]# echo ${b[0]}
1
[[email protected] shell]# echo ${b[2]}
3

2.获取数组元素个数：加个#

[[email protected] shell]# echo ${#b[*]}
3

3.数组赋值：

[[email protected] shell]# b[3]=a
[[email protected] shell]# echo ${b[*]}
1 2 3 a
[[email protected] shell]# b[3]=66
[[email protected] shell]# echo ${b[*]}
1 2 3 66

4.如果下标不存在，自动添加一个：

[[email protected] shell]# b[5]=6
[[email protected] shell]# echo ${b[*]}
1 2 3 66 6

5.删除元素：

[[email protected] shell]# unset b[3]
[[email protected] shell]# echo ${b[*]}
1 2 3 6 6
[[email protected] shell]# unset b[4]
[[email protected] shell]# echo ${b[*]}
1 2 3 6
[[email protected] shell]# unset b
[[email protected] shell]# echo ${b[*]}

6.数组分片：

[[email protected] shell]# a=(`seq 1 10`)
[[email protected] shell]# echo ${a[*]}
1 2 3 4 5 6 7 8 9 10
[[email protected] shell]# echo ${a[*]:3:4}
4 5 6 7
[[email protected] shell]# echo ${a[*]:-3:2}
1 2 3 4 5 6 7 8 9 10
[[email protected] shell]# echo ${a[*]:0-3:2}
8 9

7.数组替换：

[[email protected] shell]# echo ${a[*]/8/6}
1 2 3 4 5 6 7 6 9 10
[[email protected] shell]# a=(${a[*]/8/6})
[[email protected] shell]# echo ${a[*]}
1 2 3 4 5 6 7 6 9 10

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