目录

1.是什么？

2.写法

3.shell脚本语法

3.1第一个shell脚本

3.2交互式shell脚本

3.3shell脚本的数值计算

3.4test命令

3.5中括号【】判断符

3.6默认变量

4.shell脚本条件判断

4.1 if fi

4.2 if then else

4.3 if elif else 

4.4 case

5.shell脚本函数

5.1 无参

5.2有参

6.shell循环

6.1while

6.2for

---

1.是什么？

在linux终端一条一条命令写起来很麻烦，因此需要一个一次性包含很多条命令的”命令“

2.写法

#！/bin/bash

3.shell脚本语法

3.1第一个shell脚本

  1 #!/bin/bash
  2 
  3 echo "hello world"

 输出：hello world

3.2交互式shell脚本

 通过read读取键盘输入的字符串

  1 #!/bin/bash
  2 echo "input your name:"
  3 read name
  4 echo "your name is:"$name

  1 #!/bin/bash
  2 read -p "input your age and height:"age height
  3 echo "your age=$age,your height=$height"

3.3shell脚本的数值计算

  1 #!/bin/bash
  2 echo "input two num:"
  3 read -p "first num:" first
  4 read -p "second num:" second
  5 total=$(($first+$second))
  6 echo "$first + $second = $total"

 

3.4test命令

1.判断一个文件是否存在

  1 #!/bin/bash
  2 echo "input filename:"
  3 read -p "filename is:" filename
  4 test -e $filename && echo "$filename exist" || echo "$filename no exist"

2.判断字符串是否相等

  1 #!/bin/bash
  2 echo "input filename:"
  3 read -p "first is:" first
  4 read -p "second is:" second
  5 test  $first == $second && echo "==" || echo "!="

3.5中括号【】判断符

【】中只能输入 == 或者 ！=

  1 #!/bin/bash
  2 echo "input filename:"
  3 read -p "first is:" first
  4 read -p "second is:" second
  5 [ "$first" == "$second" ] && echo "==" || echo "!="

3.6默认变量

  1 #!/bin/bash
  2 echo "input name:" $0
  3 echo "input param num:" $#
  4 echo "first:" $0
  5 echo "second:" $1
  6 echo "whole num:" $@
  7 echo "end:" $#

4.shell脚本条件判断

4.1 if fi

  1 #!/bin/bash
  2 read -p "input (Y/N)" value
  3 
  4 if [ "$value" == "Y" ] || [ "$value" == "y" ];then
  5     echo "your input is Y"
  6     exit 0
  7 fi
  8 
  9 if [ "$value" == "N" ] || [ "$value" == "n" ];then
 10     echo "your input is N"
 11     exit 0
 12 fi

4.2 if then else

  1 #!/bin/bash
  2 read -p "input (Y/N)" value
  3 
  4 if [ "$value" == "Y" ] || [ "$value" == "y" ];then
  5     echo "your input is Y"
  6     exit 0
  7 else
  8     echo "your input is N"
  9     exit 0
 10 fi

4.3 if elif else 

  1 #!/bin/bash
  2 read -p "input (Y/N)" value
  3 
  4 if [ "$value" == "Y" ] || [ "$value" == "y" ];then
  5     echo "your input is Y"
  6     exit 0
  7 elif [ "$value" == "Y" ] || [ "$value" == "y" ];then
  8     echo "your input is N"
  9     exit 0
 10 else
 11     echo "error"
 12 fi
~          

4.4 case

  1 #!/bin/bash
  2 
  3 case $1 in
  4     "a")
  5         echo "param is:a"
  6         ;;
  7     "b")
  8         echo "param is:b"
  9         ;;
 10     *)
 11         echo "error"
 12         ;;
 13 esac

5.shell脚本函数

5.1 无参

  1 #!/bin/bash
  2 
  3 function help(){
  4     echo "help"
  5 }
  6 function close(){
  7     echo "close"
  8 }
  9 
 10 case $1 in
 11     "-h")
 12         help
 13         ;;
 14     "-c")
 15         close
 16         ;;
 17 esac

5.2有参

  1 #!/bin/bash
  2 
  3 print(){
  4     echo "first 1:$1"
  5     echo "second 2:$2"
  6 }
  7 print a b

6.shell循环

6.1while

先使用，再声明

  1 #!/bin/bash
  2 while [ "$value" != "close" ]
  3 do
  4     read -p "input :" value
  5 done
  6 
  7 echo "end while!"

6.2for

  1 #!/bin/bash
  2 
  3 for name in ljs1 ljs2 ljs3 ljs4
  4 do
  5     echo "name is: $name"
  6 done

  1 #!/bin/bash
  2 
  3 read -p "input count:" count
  4 
  5 total=0
  6 for((i=0; i<=count;i++))
  7 do
  8     total=$(($total+$i))
  9 done
 10 echo "end : $total"
~