5个Shell脚本编程入门练习例子

例子一：绘制特殊图形

#!/bin/bash

 

MAX_NO=0

 

echo -n "Enter Number between (5 to 9) : "

 read MAX_NO

 

if ! [ $MAX_NO -ge 5 -a $MAX_NO -le 9 ] ; then

 echo "WTF... I ask to enter number between 5 and 9, Try Again"

 exit 1

 fi

 

clear

 

for (( i=1; i=i; s-- ))

 do

 echo -n " "

 done

 for (( j=1; j=1; i-- ))

 do

 for (( s=i; s<=MAX_NO; s++ ))

 do

 echo -n " "

 done

 for (( j=1; j<=i; j++ ))

 do

 echo -n " ."

 done

 echo ""

 done

 

echo -e "\n\n\t\t\t Whenever you need help, Tecmint.com is always there"

你应该不会被上述例子中的“关键字”困扰了，很多都是你熟悉的，或者从它们的名字可以猜出它们的意思，如“max”设定某个变量的最大值，“for”是一个循环。

输出结果：

[root@tecmint ~]# chmod 755 Special_Pattern.sh

[root@tecmint ~]# ./Special_Pattern.sh

Enter Number between (5 to 9) : 6

       .

      . .

     . . .

    . . . .

   . . . . .

  . . . . . .

  . . . . . .

   . . . . .

    . . . .

     . . .

      . .

       .

 

        Whenever you need help, Tecmint.com is always there

如果你有其它语言的编程基础，那么学习上面的脚本对你来说应该很容易。即使你是计算机方面的新手，这个学习过程也不会太难。

例子二：五颜六色的脚本

Linux终端也是支持五颜六色的，请看下面的脚本：

#!/bin/bash

 

clear

echo -e "\033[1m Hello World"

 # bold effect

echo -e "\033[5m Blink"

       # blink effect

echo -e "\033[0m Hello World"

 # back to noraml

 

echo -e "\033[31m Hello World"

 # Red color

echo -e "\033[32m Hello World"

 # Green color

echo -e "\033[33m Hello World"

 # See remaing on screen

echo -e "\033[34m Hello World"

echo -e "\033[35m Hello World"

echo -e "\033[36m Hello World"

 

echo -e -n "\033[0m"

  # back to noraml

echo -e "\033[41m Hello World"

echo -e "\033[42m Hello World"

echo -e "\033[43m Hello World"

echo -e "\033[44m Hello World"

echo -e "\033[45m Hello World"

echo -e "\033[46m Hello World"

 

echo -e "\033[0m Hello World"

输出结果：

你可以对上面的列子举一反三，把它用到你自己的脚本中去。

例子三：加密文件/目录

下面的例子演示了如何加密一个份文件或者文件夹。目前的这个版本的脚本有一些局限，例如你必须把它和你要加密的文件/目录放到同一个文件夹下面。另外，你可能需要安装“pinentry-gui”。在Fedora下安装“pinentry-gui”的命令是：

[root@midstage ~]# yum install pinentry-gui

在Ubuntu/Debian下安装“pinentry-gui”的命令是：

[root@midstage ~]# apt-get install pinentry-gui

创建一个脚本“Encrypt.sh”，将下面的代码复制进去。你也可以从这里下载这个脚本。

#!/bin/bash

echo "Welcome, I am ready to encrypt a file/folder for you"

echo "currently I have a limitation, Place me to the same folder,

where a file to be encrypted is present"

echo "Enter the Exact File Name with extension"

read file;

gpg -c $file

echo "I have encrypted the file sucessfully..."

echo "Now I will be removing the original file"

rm -rf $file

输出结果：

[root@tecmint ~]# chmod 755 Encrypt.sh

[root@tecmint ~]# ./Encrypt.sh

 

Welcome, I am ready to encrypt a file/folder for you

currently I have a limitation, Place me to the same folder,

where a file to be encrypted is present

Enter the Exact File Name with extension

 

package.xml

 

                   Enter passphrase

 

                   Passphrase _________________________________

 

 

                   Please re-enter this passphrase

 

                   Passphrase _________________________________

 

 

I have encrypted the file successfully...

Now I will be removing the original file

代码说明：

gpg -c: 这个命令使用aka来加密文件。 在你需要的时候，你需要对加密的文件进行解密。这里我们不给出具体的代码了，你可以自己尝试着写出来。提示：使用命令 gpg -d filename.gpg > filename 可以解密一份文件。

例子四：查看服务器利用率

查看服务器的利用率是管理员的一份重要的日常工作。聪明的管理员是知道如何是这份任务自动化的。下面的这份脚本会抓取服务器的很多信息，快快试试吧！

#!/bin/bash

date;

echo "uptime:"

uptime

echo "Currently connected:"

w

echo "--------------------"

echo "Last logins:"

last -a |head -3

echo "--------------------"

echo "Disk and memory usage:"

df -h | xargs | awk '{print "Free/total disk: " $11 " / " $9}'

free -m | xargs | awk '{print "Free/total memory: " $17 " / " $8 " MB"}'

echo "--------------------"

start_log=`head -1 /var/log/messages |cut -c 1-12`

oom=`grep -ci kill /var/log/messages`

echo -n "OOM errors since $start_log :" $oom

echo ""

echo "--------------------"

echo "Utilization and most expensive processes:"

top -b |head -3

echo

top -b |head -10 |tail -4

echo "--------------------"

echo "Open TCP ports:"

nmap -p- -T4 127.0.0.1

echo "--------------------"

echo "Current connections:"

ss -s

echo "--------------------"

echo "processes:"

ps auxf --width=200

echo "--------------------"

echo "vmstat:"

vmstat 1 5

输出结果：

[root@tecmint ~]# chmod 755 Server-Health.sh

[root@tecmint ~]# ./Server-Health.sh

 

Tue Jul 16 22:01:06 IST 2013

uptime:

22:01:06 up 174 days, 4:42, 1 user, load average: 0.36, 0.25, 0.18

Currently connected:

22:01:06 up 174 days, 4:42, 1 user, load average: 0.36, 0.25, 0.18

USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT

tecmint pts/0 116.72.134.162 21:48 0.00s 0.03s 0.03s sshd: tecmint [priv]

--------------------

Last logins:

tecmint pts/0 Tue Jul 16 21:48 still logged in 116.72.134.162

tecmint pts/0 Tue Jul 16 21:24 - 21:43 (00:19) 116.72.134.162

--------------------

Disk and memory usage:

Free/total disk: 292G / 457G

Free/total memory: 3510 / 3838 MB

--------------------

OOM errors since Jul 14 03:37 : 0

--------------------

Utilization and most expensive processes:

top - 22:01:07 up 174 days, 4:42, 1 user, load average: 0.36, 0.25, 0.18

Tasks: 149 total, 1 running, 148 sleeping, 0 stopped, 0 zombie

Cpu(s): 0.1%us, 0.0%sy, 0.0%ni, 99.3%id, 0.6%wa, 0.0%hi, 0.0%si, 0.0%st

 

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

1 root 20 0 3788 1128 932 S 0.0 0.0 0:32.94 init

2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd

3 root RT 0 0 0 0 S 0.0 0.0 0:14.07 migration/0

例子五：查看硬盘使用情况及发送提示邮件

下面的这个例子展示了当硬盘的使用空间超出了预期设定的值时，如果通过脚本来发送提示邮件。

MAX=95

EMAIL=server@127.0.0.1

PART=sda1

 

USE=`df -h |grep $PART | awk '{ print $5 }' | cut -d'%' -f1`

if [ $USE -gt $MAX ]; then

echo "Percent used: $USE" | mail -s "Running out of disk space" $EMAIL

fi

说明：将上述脚本中的“USER”替换成你的用户名。你可以通过命令“mail”来查看你的邮件。