Shell scripts (functions, arrays in the shell)

function

The function is to organize a piece of code into a small unit, and give the small unit a name, when the code is used to call the name of the small unit directly.

Format: function F_name () {

Command

}

The function must be placed first, and the function name can be defined by itself.

Case one:

[Email protected] shell]# vim fun.sh

#!/bin/bash

function InP () {

Echo $ $ $ ${10} ${11} $ $# [$*]

}

INP 1 2 3 4 5 6 7 8 9 34 55

[Email protected] shell]# sh fun.sh

1 2 3 fun.sh 11 [1 2 3 4 5 6 7 8 9 34 55]

Note that the $ $ cannot print out a 10th function, and when n>=10, use {10} to get the function. $ A represents the script name. $ #表示多少个函数.

Case TWO:

[Email protected] shell]# vim fun1.sh

#/bin/bash

Sum () {

S=$[$1+$2]

Echo $s

}

Sum 22 2

[Email protected] shell]# sh fun1.sh

24

Case THREE:

Write a script and enter the network card number to display the IP on the card.

#/bin/bash

IP () {

Ifconfig |grep-a1 "$" |tail-1 |awk ' {print $} '

}

Read-p "Please input the ETH name:" E

myip= ' IP $e '

echo "$e address is $myip"

Operation Result:

[Email protected] shell]# sh fun2.sh

Please input the ETH name:ens33

ENS33 address is 192.168.52.50

Arrays in the shell

To define an array:

[[email protected] ~]# a= (1 2 3 4 5 6)

To view the entire array value:

[[email protected] ~]# echo ${a[@]}

1 2 3 4 5 6

[[email protected] ~]# echo ${a[*]}

1 2 3 4 5 6

View array Single value: (zero-based)

[[email protected] ~]# echo ${a[0]}

1

[[email protected] ~]# echo ${a[1]}

2

[[email protected] ~]# echo ${a[2]}

3

Assign or change a value to an array:

[Email protected] ~]# A[2]=AAA

[[email protected] ~]# echo ${a[*]}

1 2 AAA 4 5 6

Delete the array:

Delete a value in the array:

[Email protected] ~]# unset a[1]

[[email protected] ~]# echo ${a[*]}

1 AAA 4 5 6

[Email protected] ~]# unset a[0]

[[email protected] ~]# echo ${a[*]}

AAA 4 5 6

Delete entire array

[Email protected] ~]# unset a

[[email protected] ~]# echo ${a[*]}

Delete Note Change notes

Array shards:

[[email protected] ~]# echo ${b[@]}

1 2 3 4 5 6

Format: Echo ${array name [@]: Starting from the first few elements: intercepting a few}

Starting with the first element, intercept 2:

[[email protected] ~]# echo ${b[@]:0:2}

1 2

Starting with the second element, intercept 3:

[[email protected] ~]# echo ${b[@]:1:3}

2 3 4

So how to intercept it backwards:

Format: Echo ${array name [@]:0-number of elements: intercept several}

Starting from the bottom 2nd element, intercept 2

[[email protected] ~]# echo ${b[@]:0-2:2}

5 6

Array substitution

Temporary replacement:

[[email protected] ~]# echo ${B[@]/5/6}

1 2 3 4 6 6

[[email protected] ~]# echo ${b[@]}

1 2 3 4 5 6

Permanent Replacement:

[[email protected] ~]# b= (${B[@]/5/6})

[[email protected] ~]# echo ${b[@]}

1 2 3 4 6 6

Shell scripts (functions, arrays in the shell)