第一个script

[[email protected] script]# cat -n sh01.sh
     1    #!/bin/bash
     2    #Program:
     3    #This program shows "Hello World!" in your screen.
     4    PATH=/usr/local/java/jdk1.8.0_91/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/root/bin:~/bin
     5    export PATH;
     6    echo -e "Hello World! \a \n"
     7    exit 0

第一行：#！/bin/bash 声明这个script使用的shell名称

第二三行：注释

第四行：环境变量的声明，这样程序执行时可以直接执行一些外部命令，而不必写绝对路径

第五行：使环境变量生效

第六行：主程序部分

第七行：使用exit命令让程序中断，并且传回一个数值给系统，执行完该script后，使用echo $?可以得到该值。

[[email protected] script]# vi sh01.sh
[[email protected] script]# ./sh01.sh
Hello World!  

//查看上面script返回给系统的值
[[email protected] script]# echo $?
0

简单的shell script练习

交互式脚本：变量内容由用户确定

[[email protected] script]# cat -n sh02.sh
     1    #!/bin/bash
     2    PATH=/usr/local/java/jdk1.8.0_91/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/root/bin:~/bin
     3    export PATH
     4
     5    read -p "please input your first name:" firstname #tell user to input their name
     6    read -p "please input your last name:" lastname
     7    echo -e "\n Your full name is:$firstname $lastname"
[[email protected] script]# sh sh02.sh
please input your first name:wu
please input your last name:chao

 Your full name is:wu chao
[[email protected] script]# 

随日期变化：利用日期创建文件

//查看script脚本
[[email protected] script]# cat sh03.sh
#!/bin/bash
PATH=/usr/local/java/jdk1.8.0_91/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/root/bin:~/bin
export PATH

echo -e "I will use ‘touch‘ command to create 3 files."
read -p "please input your file name:" fileuser

filename=${fileuser:-"filename"}
date1=$(date -d -2day +%Y%m%d)
date2=$(date -d -1day +%Y%m%d)
date3=$(date +%Y%m%d)

file1=${filename}${date1}
file2=${filename}${date2}
file3=${filename}${date3}

touch "$file1"
touch "$file2"
touch "$file3"

//执行该脚本
[[email protected] script]# sh sh03.sh
I will use ‘touch‘ command to create 3 files.
please input your file name:testFile
[[email protected] script]# 

//查看结果
[[email protected] script]# ls -l testFile*
-rw-r--r--. 1 root root 0 7月  19 12:40 testFile20160717
-rw-r--r--. 1 root root 0 7月  19 12:40 testFile20160718
-rw-r--r--. 1 root root 0 7月  19 12:40 testFile20160719
[[email protected] script]# 

注：$()是执行里面的代码得到的结果。${}取变量的值。

数值运算

[[email protected] script]# cat sh04.sh
#!/bin/bash
PATH=/usr/local/java/jdk1.8.0_91/bin:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/root/bin:~/bin
export PATH

echo -e "please input two numbers:"
read -p "first number:" n1
read -p "second number:" n2

total=$(($n1*$n2))
echo -e "\n The result of $n1 * $n2 is ==> $total"
[[email protected] script]#
[[email protected] script]# sh sh04.sh
please input two numbers:
first number:12
second number:23

 The result of 12 * 23 is ==> 276
[[email protected] script]# 

var=$((运算内容))

用于计算

[[email protected] script]# echo $((23*3))
69