linux基础之Shell Script入门介绍_shell

linux基础之Shell Script

1 Shell Scipt
使用指令和基本程序设计结构写成的程序，可以完成复杂的处理流程

1.1 程序书写

复制代码代码如下:

	
	#!/bin/bash

	# Program:

	#       This program shows "Hello Wrold" in your screen.

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	echo -e "Hello World!\a\n"

	exit 0

第一行 #!/bin/bash 说明使用的shell类型,不同shell语法可能不同，所以要说明使用的是哪种shell
其它#开始的表示注释,注释一般需要说明
程序功能
版本历史
作者及联系方式
设置好PATH变量，以便直接可以调用相应路径下的命令
程序主体部分
exit 0 表示程序执行成功，向环境返回0
1.2 程序执行
bash $bash sh01.sh #如果用sh sh01.sh而sh又不是指向bash，那么sh01.sh内的语法就会不一致，因为用 #sh去解释了bash语法写的shell script,针对这个程序，如果 #$type sh #得到sh is hashed (/bin/sh) #那么会输出-e Hello world!,而非Hello world!

复制代码代码如下:

	
	$./xxx.sh $chmod +x sh01.sh $./sh01.sh

	source $ source sh01.sh

注：用bash和用source的不同在于，用bash执行时，shell script其实是在在父程序bash下新建了一个 bash子程序，这个子程序中执行，当程序执行完后，shell script里定义的变量都会随子程序的结束而消失，而用source执行时，是在父程序bash中执行,shell script里定义的变量都还在。

2 简单Shell练习

2.1 例1 接收用户输入

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to read user's input

	# Site: www.tuohang.net

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	read -p "Your first name:" firstname # tell user to input

	read -p "Your last name:" lastname # tell user to input

	echo -e "\nYour full name: $firstname $lastname"

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh02.sh

	Your first name:Minix

	Your last name:007

	Your full name: Minix 007

2.2 例2 按日期建立相似名字的文件

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to create files according to date

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	# Get filename from user

	echo -e "I will use 'touch' to create three files."

	read -p "Please input your filename:" tmpfilename

	# Prevent the user input [Enter]

	# Check whether filename exists or not

	filename=${tmpfilename:-"filename"}

	# Get the final filename according to date

	date1=$(date --date='2 days ago' +%Y%m%d) # date of 2 days ago

	date2=$(date --date='1 days ago' +%Y%m%d) # date of yesterday

	date3=$(date +%Y%m%d) # date of today

	filename1=${filename}${date1}

	filename2=${filename}${date2}

	filename3=${filename}${date3}

	# Create file

	touch "$filename1"

	touch "$filename2"

	touch "$filename3"

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh03.sh

	I will use 'touch' to create three files.

	Please input your filename:WhoKnows

	$ ls W*

	WhoKnows20130201  WhoKnows20130202  WhoKnows20130203

3 判断式
3.1 测试文件是否存在
test -e filename会根据filename是否存在返回0或1,再交由echo显示结果：

复制代码代码如下:

	
	$ test -e sh01.sh  && echo "Exists" || echo "Not exists"

	Exists

	$ test -e sh0x.sh  && echo "Exists" || echo "Not exists"

	Not exists

3.2 test常用选项
3.2.1 文件类型

复制代码代码如下:

	
	-e file :file是否存在

	-f file :file是否存在且为文件

	-d file :file是否存在且为目录

3.2.2 权限
-r file :file是否有读的权限

3.2.3 文件新旧比较
-nt file1 file2 : file1 是否比 file2新

3.2.4 整数，字符串，多重条件判断
-z string: string是否为空
例：输出指定文件类型及属性

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to output type and permission of the target file

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	# Get filename from user

	echo -e "Input name of the file that you want to check.\n"

	read -p "Filename:" filename

	test -z $filename && echo "You must input a filename." && exit 0

	# Check whether the file exists or not

	test ! -e $filename && echo "The file '$filename' DO NOT exists" && exit 0

	# Check type and permission of the file

	test -f $filename && filetype="regular file"

	test -d $filename && filetype="directory"

	test -r $filename && perm="readable"

	test -w $filename && perm="$perm writable"

	test -x $filename && perm="$perm executable"

	# Output result

	echo "The filename:$filename is a $filetype"

	echo "And Permissions are :$perm"

	exit 0

调用：

复制代码代码如下:

$ bash sh04.sh
Input name of the file that you want to check.

Filename:sh01.sh
The filename:sh01.sh is a regular file
And Permissions are :readable writable executable

3.3 使用[]判断

测试文件是否存在

复制代码代码如下:

	
	$ [ -e "sh01.sh" ] ; echo $?

	0

	$ [ -e "sh0x.sh" ] ; echo $?

	1

注意[]内空格必须有
这种方法和test的test -e "sho1.sh" ; echo $? 是一致的

4 Shell Script 参数

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to ouput parameter of the shell script

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	echo "The script's name is ==> $0"

	echo "Total parameter number is ==> $#"

	# Check whether number of the parameter is less than 2

	[ "$#" -lt 2 ] && echo "The number of parameter is less than 2.Stop here." && exit 0

	echo "The whole parameter is ==> '$@'"

	echo "The first parameter is ==> $1"

	echo "The first parameter is ==> $2"

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh05.sh 1a 2b 3c 4d

	The script's name is ==> sh05.sh

	Total parameter number is ==> 4

	The whole parameter is ==> '1a 2b 3c 4d'

	The first parameter is ==> 1a

	The first parameter is ==> 2b

注：从以上程序可以看出与参数有关的预设变量如何表示

5 条件表达式

5.1 if 结构

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to show if else expression

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	read -p "Please input [Y/N]" choice

	if [ "$choice" == "Y" ] || [ "$choice" == "y" ];then

	    echo "OK, continue"

	    exit 0

	fi

	if [ "$choice" == "N" ] || [ "$choice" == "n" ];then

	    echo "Oh, interupt"

	    exit 0

	fi

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh06.sh

	Please input [Y/N]y

	OK, continue

	$ bash sh06.sh

	Please input [Y/N]n

	Oh, interupt

5.2 if else 结构

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to show if else expression

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	read -p "Please input [Y/N]" choice

	if [ "$choice" == "Y" ] || [ "$choice" == "y" ];then

	    echo "OK, continue"

	    exit 0

	elif [ "$choice" == "N" ] || [ "$choice" == "n" ];then

	    echo "Oh, interupt"

	    exit 0

	else

	    echo "Input [Y/N]"

	fi

	exit 0

5.3 case

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to show case expression

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	read -p "Tell me your choice:[1-3]=>" choice

	case $choice in

	    "1")

	        echo "Your choice is ONE"

	    "2")

	        echo "Your choice is TWO"

	    "3")

	        echo "Your choice is THREE"

	esac

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh08.sh

	Tell me your choice:[1-3]=>2

	Your choice is TWO

	$ bash sh08.sh

	Tell me your choice:[1-3]=>1

	Your choice is ONE

	$ bash sh08.sh

	Tell me your choice:[1-3]=>3

	Your choice is THREE

6 函数

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to test function

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	function myprint(){

	    echo -n "Your choice is "

	}

	read -p "Tell me your choice:[1-3]=>" choice

	case $choice in

	    "1")

	        myprint;echo "ONE"

	    "2")

	        myprint;echo "TWO"

	    "3")

	        myprint;echo "THREE"

	esac

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh09.sh

	Tell me your choice:[1-3]=>1

	Your choice is ONE

	$ bash sh09.sh

	Tell me your choice:[1-3]=>2

	Your choice is TWO

	$ bash sh09.sh

	Tell me your choice:[1-3]=>3

	Your choice is THREE

7 循环
7.1 while

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program shows while expression

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	while [ "$choice" != "yes" ]

	do

	    read -p "Give your choice [yes/no]:" choice

	done

	exit 0

调用：

复制代码代码如下:

	
	$ bash sh10.sh

	Give your choice [yes/no]:no

	Give your choice [yes/no]:no

	Give your choice [yes/no]:nx

	Give your choice [yes/no]:yes

7.2 for

复制代码代码如下:

	
	# !/bin/bash

	# Program:

	#       This program is used to demo for expression

	# History:

	# 2013/2/3 on_1y First release

	PATH=$PATH

	export PATH

	for choice in 1 2 3

	do

	    echo "your choice is $choice"

	done

	exit 0

调用示例：

复制代码代码如下:

	
	$ bash sh11.sh

	your choice is 1

	your choice is 2

	your choice is 3

8 shell script的追踪与Debug
sh -n xx.sh # 语法检查
sh -x xx.sh # 列出xx.sh的执行过程

linux基础之Shell Script入门介绍

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