脚本 1

Posted 2020-09-23

####脚本####

Bash脚本基础

   BASH = GNU Bourne-Again Shell,BASH 是 GNU 组织开发和推广的一个项目。Bash脚本类似批处理,简单来讲就是把许多的指令集合在一起,并提供循环、条件、判断等重要功能,语法简单实用,用以编写程序,大大简化管理员的操作,并可以完成图形工具所无法实现的功能。

 

1.脚本通常以.sh结尾

2.编写脚本是通常写到

#！/bin/bash    ##/bin/bash为解释器，解释原文件名中的内容

#！/bin/sh    ##/bin/sh也为解释器

[[email protected] mnt]# chmod +x /mnt/haha.sh

[[email protected] mnt]# /mnt/haha.sh    ##直接执行脚本内容（使用脚本内部中写的解释器）

hello

 

[[email protected] mnt]# ps f    ##查看从属关系

  PID TTY      STAT   TIME COMMAND

 4114 pts/1    Ss     0:00 -bash

 4417 pts/1    T      0:00  \_ /bin/bash /mnt/ha.sh    ##使用bash解释器执行此脚本

 4418 pts/1    T      0:00  |   \_ cat

 4427 pts/1    R+     0:00  \_ ps f

 4060 tty6     Ss+    0:00 -bash

 1867 pts/0    Ss+    0:00 -bash

 1678 tty1     Ss+    0:05 /usr/bin/Xorg :0 -background none -ve

 1993 ttyS0    Ss+    0:00 /sbin/agetty --keep-baud ttyS0 115200

 

 

3.脚本调试模式：

[[email protected] mnt]# cat /mnt/ha.sh

#!/bin/bash -x    ##添加-x是为了脚本调试，会同时输出本来需要输入的内容

 echo hello

[[email protected] mnt]# /mnt/ha.sh

+ echo hello

hello

 

如果脚本中不添加-x时

sh -x /mnt/ha.sh    ##-x会输出文件本来的输入内容

 

 

 

4.引用和转义

   引用和转义在shell解析字符串时用于去除字符串中特殊字符或保留词语的特殊含义。这会导致按字面处理字符串,而不是展开变量或将其部分内容视作具有特殊含义。

引用有三种类型:

1）

弱引用

   将字符串放置在双引号中,保留字符串中所有字符的文字值,$、`、\和!字符除外。换言之,变量扩展和命令扩展在双引号内仍起作用。

echo “can I have a $FRUIT”

echo “The current time is $(date +%r).”

$i    ##指变量值

i    ##指变量

$    ##变量取值

`    ##让指令先执行

\    ##引用单个字符

""    ##引用部分字符（‘‘ $  ! 这三个均不引用）————这个为弱引用

2）

强引用

将字符串放置在单引号中,保留字符串中所有字符的文字值,同时禁用所有扩展:

‘    ##转译所有的字符

3）

转义

非引用的\是转义字符。它保留了下一个字符的文字值。(例如,\$PATH是确切的字符串$PATH,而

不是PATH变量的内容。)

\    ##转译单个字符

 

测试：

 

[[email protected] ~]# echo # not a comment #

[[email protected] ~]# echo \# not a comment #

# not a comment

[[email protected] ~]# echo \# not a comment \#

# not a comment #

[[email protected] ~]# echo ‘# not a comment #‘

# not a comment #

[[email protected] ~]# echo ‘$HOME‘

$HOME

[[email protected] ~]# echo ‘`pwd`‘

`pwd`

[[email protected] ~]# echo ‘"Hello,world"‘

"Hello,world"

[[email protected] ~]# echo "$HOME"

/root

[[email protected] ~]# echo "`pwd`"

/root

[[email protected] ~]# echo ""Hello, world""

Hello, world

[[email protected] ~]# echo "\$HOME"

$HOME

[[email protected] ~]# echo "\`pwd\`"

`pwd`

[[email protected] ~]# echo "\"Hello, world\""

"Hello, world"

 

 

5.Shell变量

shell变量用于为稍后在脚本中使用的名称指定值,并且仅限于shell命令行或从中声明变量的脚本。

若要定义或指定值:

FRUIT=apple

若要参考或使用变量:

$FRUIT

${FRUIT}

[[email protected] ~]# FIRST=John

[[email protected] ~]# LAST=Doe

[[email protected] ~]# echo $FIRST $LAST

John Doe

[[email protected] ~]# echo $FIRST_$LAST

Doe

[[email protected] ~]# echo ${FIRST}_$LAST

John_Doe

 

 

6.循环

for NUM in 1 hello 2 westos 3 lee;do echo$NUM ; done     ##NUM后面是6个数

for NUM in 1 hello 2 westos 3 lee;do echo$NUM ;sleep 1； done    ##执行完上一个的时候停一秒执行下一个

[[email protected] ~]# for HOST in host{1..3};do echo $HOST;done

host1

host2

host3

 

7.条件语句

a=1

while [ "$a" -ge "1" -a "$a" -lt "10" ]; do echo yes; break;done    ##当a大于等于1，小于10的时候输出yes

yes

 

-ge     大于等于

-gt    大于

-lt    小于

 

 

实验：

1)要求：测试1～10主机是否能ping

[[email protected] mnt]# vim haha.sh

[[email protected] mnt]# cat haha.sh

#!/bin/bash

for i in {1..10}

do ping -c1 -w1 172.25.254.$i &> /dev/null && echo 172.25.254.$i is up || echo 172.25.254.$i is down    ##-c1执行次数，-w1等待时间

done  

[[email protected] mnt]# /mnt/haha.sh

172.25.254.1 is up

172.25.254.2 is up

172.25.254.3 is up

172.25.254.4 is up

172.25.254.5 is up

172.25.254.6 is up

172.25.254.7 is up

172.25.254.8 is down

172.25.254.9 is up

172.25.254.10 is up

 

##脚本调试模式的测试

[[email protected] mnt]# sh -x /mnt/haha.sh

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.1

+ echo 172.25.254.1 is up

172.25.254.1 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.2

+ echo 172.25.254.2 is up

172.25.254.2 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.3

+ echo 172.25.254.3 is up

172.25.254.3 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.4

+ echo 172.25.254.4 is up

172.25.254.4 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.5

+ echo 172.25.254.5 is up

172.25.254.5 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.6

+ echo 172.25.254.6 is up

172.25.254.6 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.7

+ echo 172.25.254.7 is up

172.25.254.7 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.8

+ echo 172.25.254.8 is down

172.25.254.8 is down

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.9

+ echo 172.25.254.9 is up

172.25.254.9 is up

+ for i in ‘{1..10}‘

+ ping -c1 -w1 172.25.254.10

+ echo 172.25.254.10 is up

172.25.254.10 is up

[[email protected] mnt]#

 

 

2)要求：自动建立用户

[[email protected] mnt]# cat /mnt/username

xiao

ha

xi

[[email protected] mnt]# cat create_user.sh

#!/bin/bash

for name in `cat /mnt/username` 或者 for name in `cat $1`

do useradd $name

done

[[email protected] mnt]# sh create_user.sh username

[[email protected] mnt]# id xiao

uid=1001(xiao) gid=1001(xiao) groups=1001(xiao)

[[email protected] mnt]# id xi

uid=1003(xi) gid=1003(xi) groups=1003(xi)

[[email protected] mnt]# id ha

uid=1002(ha) gid=1002(ha) groups=1002(ha)

 

3)要求：将/etc/*.conf 文件复制到/mnt/$BACKDIR下

vim /mnt/backup.sh

#！/bin/bash

BACKDIR=etcconfig-`date +%Y-%m-%d-%S`##年月日秒

mkdir -p /mnt/$BACKDIR

cp /etc/*.conf /mnt/$BACKDIR

 

chmod +x backup.sh

 

/mnt/backup.sh

cd /mnt

ls

 

4)要求：倒计时5秒

[[email protected] mnt]# cat text3.sh

#!/bin/bash

for ((i=5;i>0;i--))

do

echo -n After ${i}s is end

echo -ne "\r\r"

sleep 1

done

[[email protected] mnt]# chmod +x /mnt/text3.sh

[[email protected] mnt]# /mnt/text3.sh

After 4s is end

 

5)要求：70s倒计时

[[email protected] mnt]# cat text4.sh

#!/bin/bash

MIN=1

for ((SEC=10;SEC>=0;SEC--))

do

while [ "$SEC" -eq "0" -a "$MIN" -eq "0" ]

do

echo "TIME is END"

exit 0

done

 

while [ "$SEC" -eq "0" -a "$MIN" -ge "0" ]

do

(( MIN-- ))

SEC=59

echo -n "After ${MIN}min:${SEC}s is end "

sleep 1

echo -ne "\r\r"

done

echo -n "After ${MIN}min:${SEC}s is end "

echo -ne "\r\r"

sleep 1

done

 

[[email protected] mnt]# /mnt/text4.sh

TIME is END

 

 

 

6）要求：脚本mysql的备份

#!/bin/bash

for DB in $(mysql -uroot -e "show databases" -E -N | grep -v ‘^*‘ | grep -v ‘schema$‘)

        do

        echo "Backing up $DB"

        mysqldump -uroot $DB > /dbbackup/$DB-`date +%Y-%m-%d`.dump##备份到这块（重定向）

        done

echo ""

for DBDUMP in /dbbackup/*

        do

        SIZE=$(stat --printf "%s\n" $DBDUMP)

        echo "$DBDUMP $SIZE"

        done

 

[[email protected] mnt]# /mnt/text5.sh

Backing up mysql

Backing up test

Backing up westos

 

/dbbackup/mysql-2017-06-11.dump 514670

/dbbackup/test-2017-06-11.dump 1261

/dbbackup/westos-2017-06-11.dump 1835

 

 

7）要求：查找设备ip

[[email protected] mnt]# vim change_show.sh

#!/bin/bash

read -p "please give me a interface:"

ifconfig eth0 | grep netmask | awk -F " " ‘{print $2}‘

 

[[email protected] mnt]# /mnt/change_show.sh

please give me a interface:eth0

172.25.254.113

 

带提示的查找：

[[email protected] mnt]# vim text6.sh

#!/bin/bash

echo `ifconfig | grep flags | cut -d : -f 1`

read -p "please give me a interface:"

ifconfig $1 | grep netmask | awk -F " " ‘{print $2}‘

[[email protected] mnt]# /mnt/text6.sh eth0

eth0 eth1 eth2 lo team0

please give me a interface:eth0

172.25.254.113

 

 

8）要求：输入ip判断网是否通畅

[[email protected] mnt]# vim text7.sh

#!/bin/bash

while [ "$#" -eq "0" ]

do

echo "please give me a ip address!"

exit 1

done

ping -c 1 -w 1 $1 > /devnull && echo "$1 is up" || echo "$1 is down"

 

[[email protected] mnt]# chmod +x text7.sh

[[email protected] mnt]# /mnt/text7.sh

please give me a ip address!

[[email protected] mnt]# /mnt/text7.sh  172.25.254.13

172.25.254.13 is up

[[email protected] mnt]# /mnt/text7.sh  172.25.254.77

172.25.254.77 is down

 

 

 

退出状态

Linux命令完成时,将返回退出状态。成功完成程序时,将返回0的推出状态。这被bash当作逻辑True值。非零退出状态通常表示发生了错误,并且被bash当作逻辑False值。

例如:grep的退出状态的含义:

0 – 在指定的文件中找到了模式

1 – 在指定的文件中未找到模式

>1 – 一些其他错误(无法打开文件、错误的搜索表达式等)

推出状态的值被存储在"?"中,可以使用以下命令查看:

# echo $?

 

 

 

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