Shell 编程入门教程

 1#!/bin/bash
 2
 3let var=2
 4# 常用写法
 5if [ $var -eq 0 ]
 6then
 7    echo "var is 0"
 8fi
 9
10# 常用写法2
11if [ $var -eq 0 ]; then
12    echo "var is 0"
13fi
14
15# 直接写test方式
16if test $var -eq 0
17then
18    echo "var is 0"
19fi
20
21# if-else
22if [ $var -eq 0 ]
23then
24   echo "var is 0"
25else
26   echo "var is other number."
27fi
28
29# if-elif-else
30if [ $var -eq 0 ]
31then
32   echo "var is 0"
33elif [ $var -eq 1 ]
34then
35   echo "var is 1"
36else
37   echo "var is other number."
38fi

 1#!/bin/bash
 2
 3read -p "please intput a animal name: " a
 4# 匹配字符串
 5case $a in
 6cat)
 7    echo "this is a cat."
 8    ;;
 9fish)
10    echo "this is a fish."
11    ;;
12*)
13    echo "another animal."
14esac
15
16# 匹配数字
17case $a in
181)
19    echo "match number 1"
20    ;;
212)
22    echo "match number 2"
23    ;;
24*)
25    echo "unknow number: $a"
26esac

 1#!/bin/bash
 2
 3echo "-----------"
 4echo "all args:$*"
 5echo "all args:$@"
 6echo "-----------"
 7
 8# 常用, $*可以替换为$@，都获取执行脚本时所有参数
 9for a in $*
10do
11    echo "$a"
12done
13
14# 循环1到5, in后面的{}中为一组内容，数字或文本都可
15# {1..5} 等价于 {1,2,3,4,5}
16for a in {1,2,3,4,5}
17do
18    echo "$a"
19done
20
21# 循环1到5
22for a in 1 2 3 4 5
23do
24    echo "$a"
25done
26
27# C语言风格, 循环1~5
28for (( i=1; i<=5; i++ ))
29do
30    echo "$i"
31done
32
33# -------------
34# 输出当前目录中以.sh结尾的文件
35for n in `ls *.sh`
36{
37    echo $n
38}
39
40# 输出 1~10，{1..10} 产生1~10序列，等价于 seq 10
41for a in {1..10}
42{
43    echo $a
44}

 1**#!/bin/bash
 2
 3let var=1
 4
 5# 常用, 循环1~5
 6while [ $var -le 5 ]
 7do
 8    echo "$var"
 9    let var=$var+1
10done
11
12let var=1
13while [ $var -le 5 ]
14do
15    echo "$var"
16    let var++
17done

 1#!/bin/bash
 2
 3let var=1
 4
 5# 常用, 循环0~5
 6while [ $var -le 5 ]
 7do
 8    if [ $var -eq 2 ]
 9    then
10        echo "now var=$var, break while."
11        break
12    fi
13
14    echo "$var"
15    let var=$var+1
16done
17
18echo "----------------------"
19
20let var=1
21while [ $var -le 5 ]
22do
23
24    if [ $var -eq 2 ]
25    then
26        echo "now var=$var, conticned the second cycle."
27        break
28    fi
29
30    echo "$var"
31    let var++
32done

 1#!/bin/bash
 2
 3# 定义函数方式1
 4fun1()
 5{
 6    echo "called fun1"
 7}
 8
 9# 定义函数方式2
10function fun2
11{
12    echo "called fun2"
13}
14
15#调用函数
16fun1
17fun2

 1#!/bin/bash
 2# 通过读取脚本的第一输入参数值求其阶乘, 并输出结果
 3
 4# 递归求阶乘函数
 5function jie
 6{
 7    if [ $1 -le 1 ]
 8    then
 9        echo 1
10    else
11        x=`jie $[$1-1]`
12        echo $[$1*x]
13    fi
14}
15
16# 调用计算
17res=$(jie $1) # 此处函数jie接收的第一个参数为此脚本运行时的第一个参数
18echo "res=$res" # 接收echo输出的返回值

 1#!/bin/bash
 2
 3declare -a arr[10]
 4# 即使下标越界(i>=10)也不会报错
 5for ((i=0;i<10;i++))
 6{
 7    arr[i]=$[i+1]
 8}
 9
10# 输出
11for ((k=0;k<10;k++))
12{
13    echo ${arr[k]}
14}