shell script 入门

在 shell script 的撰写中还需要用到底下的注意事项：

1. 指令的执行是从上而下、从左而右的分析与执行；
2. 指令的执行就如同第五章内提到的：指令、选项不参数间的多个空白都会被忽略掉；
3. 空白行也将被忽略掉，而且 [tab] 按键所推开的空白同样规为空格键；
4. 如果读取到一个 Enter 符号 (CR) ，就尝试开始执行该行 (或该串) 命令；
5. 至亍如果一行的内容太多，则可以使用『 \[Enter] 』来延伸至下一行；
6. 『 # 』可做为批注！任何加在 # 后面的资料将全部被规为批注文字而被忽略！

第一个shell script，必须是hello world。哈哈

#!/bin/bash

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin

export PATH
echo -e  "hello world!  \n"
exit 0

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh01.sh
hello world!

特此说明一下，Ubuntu默认的shell是dash，而不是bash，echo -e时候会有问题，会把-e也打印出来。

转载link：http://webnoties.blog.163.com/blog/static/1835251412013518362635/

很谢谢作者的blog帮我搞定了这个默认shell不是bash的问题

因为ubuntu默认的sh是连接到dash的,又因为dash跟bash的不兼容所以出错了.执行时可以把sh换成bash 文件名.sh来执行.成功.dash是什么东西,查了一下,应该也是一种shell,貌似用户对它的诟病颇多.
by the way修改sh默认连接到bash的一种方法：
sudo dpkg-reconfigure dash
选择no即可.

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.29 
# code file   : sh02.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program would ask the user to input some varible's value
#       and then print them out into the screen.

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

read -p "Please input your first name:" first_name #give the user a message whatshould be inputed
read -p "Please input your second name" second_name
echo -e "\nYour full name is $first_name $second_name" #print out the user's name

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh02.sh
Please input your first name:Jason
Please input your second nameLeaster

Your full name is Jason Leaster

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.29
# code file   : sh04.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for demonstrating some
#       mathmatical operations on varibles which in bash script
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

echo -e "You SHOULD input 2 numbers ,I will cross them !\n"
read -p "first number: " first_num
read -p "second number: " second_num

total=$(($first_num*second_num))

echo -e "total is : $total"

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh04.sh
You SHOULD input 2 numbers ,I will cross them !

first number: 10
second number: 25
total is : 250

不怕丢人的说，上面这地方写成$(total)差点纠结而shi。。。。

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.29 
# code file   : sh05.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for command -- test
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

echo -e "Please input a filename, I will check the filename's type and permission.\n\n"
read -p "Input a filename : " filename

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

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

test -f $filename && filetype="regulare file"
test -d $filename && filetype="directory"
test -r $filename && perm="readable"
test -w $filename && perm="writable"
test -x $filename && perm="excutable"

echo "The filename: $filename is a $filetype"
echo "And the permissions are: $perm"

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh05.sh
Please input a filename, I will check the filename‘s type and permission.

Input a filename : sh01.sh
The filename: sh01.sh is a regulare file
And the permissions are: writable

删除一个环境变量用 unset 环境变量名

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.29
# code file   : sh06.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for [ A==B ]
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

read -p "Please input (Y/N) : " yn
[ "$yn" == "Y" -o "$yn" == "y" ] && echo "OK, continue" && exit 0
[ "$yn" == "N" -o "$yn" == "n" ] && echo "NO,interrupt" && exit 0
echo "I don't know what you choice is" && exit 0

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh06.sh
Please input (Y/N) : y
OK, continue

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.29 
# code file   : sh07.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo that user input a file name
#       and some parameters, lately program process it and print out the file
#       type and permission.
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

echo "The script name is ==> $0"
echo "Total parameter numbe is ==> $#"
[ "$#" -lt 2 ] && echo "The number of parameter is less than 2. Stop here" && exit 0
echo "Your whole parameter is ==> $@"
echo "1st parameter ==> $1"
echo "2nd parameter ==> $2"

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh07.sh
The script name is ==> ./sh07.sh
Total parameter numbe is ==> 0
The number of parameter is less than 2. Stop here
jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh07.sh hello world
The script name is ==> ./sh07.sh
Total parameter numbe is ==> 2
Your whole parameter is ==> hello world
1st parameter ==> hello
2nd parameter ==> world

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.30 
# code file   : sh08.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for command -- shift
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

echo "Total parameter number is ==> $#"
echo "Your whole parameter is ==> $@"
shift
echo "Total parameter number is ==> $#"
echo "Your whole parameter is ==> $@"
shift 3
echo "Total parameter number is ==> $#"
echo "Your whole parameter is ==> $@"

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh08.sh
Total parameter number is ==> 0
Your whole parameter is ==>
Total parameter number is ==> 0
Your whole parameter is ==>
Total parameter number is ==> 0
Your whole parameter is ==>
jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh08.sh hello world
Total parameter number is ==> 2
Your whole parameter is ==> hello world
Total parameter number is ==> 1
Your whole parameter is ==> world
Total parameter number is ==> 1
Your whole parameter is ==> world
jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh08.sh hello world jason leaster tonight
Total parameter number is ==> 5
Your whole parameter is ==> hello world jason leaster tonight
Total parameter number is ==> 4
Your whole parameter is ==> world jason leaster tonight
Total parameter number is ==> 1
Your whole parameter is ==> tonight

有意思的是如果文件名之后没有“参数”，parameter number就是0，如果参数少于shift移动的距离(比方说代码中的shift 3),就会保留最低数目为1，如果参数少于shift移动的距离

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.30
# code file   : sh08.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for "if[] ; then fi"
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

read -p "Please input (Y/N) :" yn

if [ "$yn" == "Y" -o "$yn" == "y" ]; then
        echo "OK,continue"
        exit 0
fi

if [ "$yn" == "N" -o "$yn" == "n" ]; then
        echo "Oh,interrupt!"
        exit 0
fi

echo "I don't know what your choice is" && exit 0

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh09.sh
Please input (Y/N) :y
OK,continue
jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh09.sh
Please input (Y/N) :n
Oh,interrupt!

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.30
# code file   : sh9.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for "if[] ; elif [] ;then else fi"
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

read -p "Please input (Y/N) :" yn

if [ "$yn" == "Y" -o "$yn" == "y" ]; then
        echo "OK,continue"
        exit 0
elif [ "$yn" == "N" -o "$yn" == "n" ];then
        echo "Oh,interrupt!"
        exit 0
else
        echo "Are you kidding me? You don't know what means \"Input (Y/N)\" \n"
fi

echo "I don't know what your choice is" && exit 0

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh10.sh
Please input (Y/N) :hehe
Are you kidding me? You don‘t know what means "Input (Y/N)" \n
I don‘t know what your choice is

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.30
# code file   : sh10.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for "if[] ; elif [] ;then else fi"
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

echo "This program will print your selection !"

case $1 in
        "one")
        echo "Your choice is ONE"
        ;;
        "two")
        echo "Your choice is TWO"
        ;;
        *)
        echo "42"
        ;;
esac

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh12.sh hello world
This program will print your selection !
42

#! /bin/bash

# code writer : EOF
# code date   : 2014.07.30 
# code file   : sh13.sh
# e-mail      : jasonleaster@gmail.com
# code purpose:
#               This program was coded for a demo for "function and while loop"
#       If you find something wrong with my code, please touch me.
#       Thank you!

PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:~/bin
export PATH

function secret()
{
        echo "hello world!"
}

temp=10

while [  $temp != 0 ]
do
        secret
        temp=$(($temp-1))
        echo "$temp"
done

jasonleaster@ubuntu:~/shell_script_beginner$ sh ./sh13.sh
hello world!
9
hello world!
8
hello world!
7
hello world!
6
hello world!
5
hello world!
4
hello world!
3
hello world!
2
hello world!
1
hello world!
0

最后sh -x将使用do啊的script 内容显示到屏幕上，这是很有用的参数，而-n不会显示任何信息

jasonleaster@ubuntu:~/shell_script_beginner$ sh -x ./sh13.sh
+ PATH=/bin/:/sbin/:/usr/sbin/:/usr/local/sbin/:/usr/local/sbin:/home/liuzjian/bin
+ export PATH
+ temp=2
+ ‘[‘ 2 ‘!=‘ 0 ‘]‘
+ secret
+ echo ‘hello world!‘
hello world!
+ temp=1
+ echo 1
1
+ ‘[‘ 1 ‘!=‘ 0 ‘]‘
+ secret
+ echo ‘hello world!‘
hello world!
+ temp=0
+ echo 0
0
+ ‘[‘ 0 ‘!=‘ 0 ‘]‘

去衡山的时候，在白龙潭(应该是吧，不记得啦。。。)遇见的两个小孩。。。多么美好年纪啊。。。

声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉：投诉/举报工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。

联系
我们

首页 > 代码库 > shell script 入门 笔记

shell script 入门 笔记

shell script 入门

看完仍有疑问？有类似问题直接问程序猿

首页 > 代码库 > shell script 入门笔记

shell script 入门笔记