Shell编程之for和select循环

一、for和select循环

1.for循环语法

for 变量名 in 变量取值列表
do
	指令...
done

C语言型for循环

for ((exp1; exp2; exp3))
do
	指令...
done

示例：

for ((i=1;i<=3;i++))
do
	echo $i
done

说明：

• 第一个是变量初始化
• 第二个是变量范围
• 第三个是变量自增或自减

2.for循环实践

（1）打印5、4、3、2、1这5个数字

[root@codis-178 ~]# cat 11_1.sh 
#!/bin/bash
for num in 5 4 3 2 1
do
	echo $num
done
[root@codis-178 ~]# sh 11_1.sh 
5
4
3
2
1

其他方式：
[root@codis-178 ~]# cat 11_1_1.sh 
#!/bin/bash
for num in {5..1}
do
	echo $num
done

（2）获取当前目录下的目录或文件，并将其作为变量列表打印输出

[root@codis-178 ~]# mkdir -p /test/{text.txt,oldboy.txt,oldgirl.txt}
[root@codis-178 ~]# ls -l /test/
total 12
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldboy.txt
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldgirl.txt
drwxr-xr-x 2 root root 4096 Aug 23 10:42 text.txt


[root@codis-178 ~]# cat 11_2.sh 
#!/bin/bash
cd /test
for filename in `ls`
do
	echo $filename
done
[root@codis-178 ~]# sh 11_2.sh 
oldboy.txt
oldgirl.txt
text.txt

（3）用for循环批量修改文件扩展名（把txt改成jpg）

[root@codis-178 ~]# cat 11_3.sh 
#!/bin/bash
cd /test
for filename in `ls|grep "txt$"`
do
	mv $filename `echo $filename|cut -d . -f1`.jpg
done
[root@codis-178 ~]# sh 11_3.sh 
[root@codis-178 ~]# ls -l /test/
total 12
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldboy.jpg
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldgirl.jpg
drwxr-xr-x 2 root root 4096 Aug 23 10:42 text.jpg

简介方法：
[root@codis-178 ~]# rename "jpg" "gif" /test/*.jpg
[root@codis-178 ~]# ls -l /test/
total 12
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldboy.gif
drwxr-xr-x 2 root root 4096 Aug 23 10:42 oldgirl.gif
drwxr-xr-x 2 root root 4096 Aug 23 10:42 text.gif

3.企业应用

（1）批量修改文件名，去掉"_finished"

sed版
[root@codis-178 ~]# cat 11_4.sh 
#!/bin/bash
cd /test
for file in `ls *.log`
do
	mv $file `echo $file|sed 's/_finished//g'`
done
[root@codis-178 ~]# sh 11_4.sh 
[root@codis-178 ~]# ll /test/*.log
-rw-r--r-- 1 root root 0 Aug 23 11:03 /test/sku_102999_1.log
-rw-r--r-- 1 root root 0 Aug 23 11:03 /test/sku_102999_2.log
-rw-r--r-- 1 root root 0 Aug 23 11:03 /test/sku_102999_3.log
-rw-r--r-- 1 root root 0 Aug 23 11:03 /test/sku_102999_4.log
-rw-r--r-- 1 root root 0 Aug 23 11:03 /test/sku_102999_5.log

rename版
rename "_finished' "' *.jpg

（2）在生产环境下，批量去掉测试数据所用的bd字符

[root@codis-178 test]# ll
total 0
-rw-r--r-- 1 root root 0 Aug 23 11:09 bd502.html
-rw-r--r-- 1 root root 0 Aug 23 11:09 bd503.html
-rw-r--r-- 1 root root 0 Aug 23 11:09 bd504.html
[root@codis-178 test]# rename "bd" "" *.html
[root@codis-178 test]# ll
total 0
-rw-r--r-- 1 root root 0 Aug 23 11:09 502.html
-rw-r--r-- 1 root root 0 Aug 23 11:09 503.html
-rw-r--r-- 1 root root 0 Aug 23 11:09 504.html

（3）通过脚本实现仅sshd、rsyslog、crond、network、sysstat服务在开机时启动

方法一：
for oldboy in `chkconfig --list|grep "3:on"|awk '{print $1}'|grep -vE "crond|network|sshd|rsyslog|sysstat"`;do chkconfig $oldboy off;done

方法二：
chkconfig --list|grep -vE "crond|network|sshd|rsyslog|sysstat"|awk '{print "chkconfig " $1 " off"}'|bash

（4）打印九九乘法表

[root@codis-178 ~]# cat 11_5.sh
#!/bin/bash
COLOR='E[47;30m'
RES='E[0m'

for num1 in `seq 9`
do
	for num2 in `seq 9`
	do
		if [ $num1 -ge $num2 ];then
			if (((num1*num2)>9))
				then
					echo -en "${COLOR}${num1}x${num2}=$((num1*num2))${RES} "
			else
				echo -en "${COLOR}${num1}x${num2}=$((num1*num2))${RES}  "
			fi
		fi
	done
	echo " "
done
[root@codis-178 ~]# sh 11_5.sh 
1x1=1   
2x1=2  2x2=4   
3x1=3  3x2=6  3x3=9   
4x1=4  4x2=8  4x3=12 4x4=16  
5x1=5  5x2=10 5x3=15 5x4=20 5x5=25  
6x1=6  6x2=12 6x3=18 6x4=24 6x5=30 6x6=36  
7x1=7  7x2=14 7x3=21 7x4=28 7x5=35 7x6=42 7x7=49  
8x1=8  8x2=16 8x3=24 8x4=32 8x5=40 8x6=48 8x7=56 8x8=64  
9x1=9  9x2=18 9x3=27 9x4=36 9x5=45 9x6=54 9x7=63 9x8=72 9x9=81

（5）计算1到100之和

[root@codis-178 ~]# cat 11_6.sh
#!/bin/bash
for ((i=1;i<=100;i++))
do
	((sum=sum+i))
done
echo $sum
[root@codis-178 ~]# sh 11_6.sh
5050

4.for循环高级应用

（1）实现MySQL分库备份脚本

[root@codis-178 ~]# cat 11_7.sh 
#!/bin/bash
PATH="/app/mysql/bin:$PATH"
DBPATH=/server/backup
MYUSER=root
MYPASS=oldboy123
SOCKET=/data/3306/mysql.sock
MYCMD="mysql -u$MYUSER -p$MYPASS -S $SOCKET"
MYDUMP="mysqldump -u$MYUSER -p$MYPASS -S $SOCKET"
[ ! -d "$DBPATH" ] && mkdir $DBPATH
for dbname in `$MYCMD -e "show databases;"|sed '1,2d'|egrep -v "mysql|schema"`
do
	$MYDUMP $dbname|gzip >$DBPATH/${dbname}_$(date +%F).sql.gz
done

（2）实现MySQL分库分表备份脚本

批量插入数据
[root@codis-178 ~]# cat 11_7_1.sh 
#!/bin/bash
PATH="/app/mysql/bin:$PATH"
DBPATH=/server/backup
MYUSER=root
MYPASS=oldboy123
SOCKET=/data/3306/mysql.sock
MYCMD="mysql -u$MYUSER -p$MYPASS -S $SOCKET"
MYDUMP="mysqldump -u$MYUSER -p$MYPASS -S $SOCKET"
for dbname in oldboy oldgirl xiaoting bingbing
do
	$MYCMD -e "use $dbname;create table test(id int,name varchar(16)); insert into test values(1,'testdata');"
done

备份脚本
[root@codis-178 ~]# cat 11_7_2.sh 
#!/bin/bash
PATH="/app/mysql/bin:$PATH"
DBPATH=/server/backup
MYUSER=root
MYPASS=oldboy123
SOCKET=/data/3306/mysql.sock
MYCMD="mysql -u$MYUSER -p$MYPASS -S $SOCKET"
MYDUMP="mysqldump -u$MYUSER -p$MYPASS -S $SOCKET"
[ ! -d "$DBPATH" ] && mkdir $DBPATH
for dbname in `$MYCMD -e "show databases;"|sed '1,2d'|egrep -v "mysql|schema"`
do
	mkdir $DBPATH/${dbname}_$(date +%F) -p
	for table in `$MYCMD -e "show tables from $dbname;"|sed '1d'`
	do
		$MYDUMP $dbname $table|gzip >$DBPATH/${dbname}_$(date +%F)/${dbname}_${table}.sql.gz
	done
done

（3）批量检查Web服务是否正常，并发送相关邮件或手机报警

[root@codis-178 ~]# cat 11_8.sh 
#!/bin/bash
path=/server/scripts
MAIL_GROUP="1111@qq.com 2222@qq.com"
PAGER+GROUP="18600338340 18911718229"
LOG_FILE="/tmp/web_check.log"

[ ! -d "$path" ] && mkdir -p $path
function UrlList(){
	cat >$path/domain.list<<EOF
	http://www.baidu.com
	http://www.163.com
	http://www.sina.com
EOF
}
function CheckUrl(){
	FAILCOUNT=0
	for ((i=1;$i<=3;i++))
	do
		wget -T 5 --tries=1 --spider $1 >/dev/null 2>&1

		if [ $? -ne 0 ];then
			let FAILCOUNT+=1
		else
			break
		fi
	done
	return $FAILCOUNT
}

function MAIL(){
	local SUBJECT_CONTENT=$1
	for MAIL_USER in `echo $MAIL_FROUP`
	do
		mail -s "$SUBJECT_CONTENT " $MAIL_USER <$LOG_FILE
	done
}
function PAGER(){
	for PAGER_USER in `echo $PAGER_GROUP`
	do
		TITLE=$1
		CONTACT=$PAGER_USER
		HTTPGW=http://oldboy.sms.cn/smsproxy/sendsms.action
		curl -d cdkey=5ADF-EFA -d password=OLDBOY -d phone=$CONTACT -d message="$TITLE[$2]" $HTTPGW
	done
}
function SendMsg(){
	if [ $1 -ge 3 ];then
		RETVAL=1
		NOW_TIME=`date +%Y-%m-%d %H:%M:%S`
		SUBJECT_CONTENT="http://$2 is error,${NOW_TIME}"
		echo -e "$SUBJECT_CONTENT" |tee $LOG_FILE
		MAIL $SUBJECT_CONTENT
		PAGER $SUBJECT_CONTENT $NOW_TIME
	else
		echo "http://$2 is ok"
		RETVAL=0
	fi
	return $RETVAL
}
function main(){
	UrlList
	for url in `cat $path/domain.list`
	do
		CheckUrl $url
		SendMsg $? $url
	done
}
main

（4）批量建10个账号，并设置密码（随机数，但必须是字符和数字混合）

[root@codis-178 ~]# cat 11_9.sh 
#!/bin/bash
. /etc/init.d/functions
user="xiaoda01"
passfile="/tmp/user.log"
for num in `seq -w 10`
do
	pass="`echo "test$RANDOM"|md5sum|cut -c 3-11`"
	useradd $user$num &>/dev/null &&
	echo -e "$user${num}:$pass" >>$passfile
	if [ $? -eq 0 ];then
		action "$user$num is ok" /bin/true
	else
		action "$user$num is fail" /bin/false
	fi
done
echo -------------------------------
chpasswd < $passfile
cat $passfile && >$passfile
[root@codis-178 ~]# sh 11_9.sh 
xiaoda0101 is ok                                           [  OK  ]
xiaoda0102 is ok                                           [  OK  ]
xiaoda0103 is ok                                           [  OK  ]
xiaoda0104 is ok                                           [  OK  ]
xiaoda0105 is ok                                           [  OK  ]
xiaoda0106 is ok                                           [  OK  ]
xiaoda0107 is ok                                           [  OK  ]
xiaoda0108 is ok                                           [  OK  ]
xiaoda0109 is ok                                           [  OK  ]
xiaoda0110 is ok                                           [  OK  ]
-------------------------------
xiaoda0101:1d2311ee7
xiaoda0102:cfa830b4d
xiaoda0103:82920ccf0
xiaoda0104:c74f8c425
xiaoda0105:f54760e68
xiaoda0106:e6d4d939d
xiaoda0107:364ca359e
xiaoda0108:3d1a8afb0
xiaoda0109:c7709971b
xiaoda0110:6d8ab529c

二、随机数生成方法

1.系统变量$RANDOM（0~32767）

[root@codis-178 ~]# echo $RANDOM
11639
[root@codis-178 ~]# echo $RANDOM
26729

2.通过openssl产生

[root@codis-178 ~]# openssl rand -base64 8
093jnyH8wW0=
[root@codis-178 ~]# openssl rand -base64 16
wbdEcXUylW09GcQZdPfumQ==
[root@codis-178 ~]# openssl rand -base64 16
mj2ZsMWN5kGcAxG/uvyeBw==

3.通过时间date

[root@codis-178 ~]# date +%s%N
1503467625592127445
[root@codis-178 ~]# date +%s%N
1503467628842171721

4.通过/dev/urandom配合cksum

[root@codis-178 ~]# head /dev/urandom |cksum 
3335560219 3028
[root@codis-178 ~]# head /dev/urandom |cksum 
1646715305 2885

说明：
/dev/urandom设备存储着系统当前运行环境的实时数据，可以看作系统在某个时候的唯一值。

5.通过UUID

[root@codis-178 ~]# cat /proc/sys/kernel/random/uuid 
92062c1c-ccc3-4d4d-939a-827b6f93f3d9
[root@codis-178 ~]# cat /proc/sys/kernel/random/uuid 
5a274f33-ad1c-4ad1-bc86-d6b472dec70a
[root@codis-178 ~]# cat /proc/sys/kernel/random/uuid 
7178879c-fcf7-4acb-8b43-5936bc403336

说明：
UUID码是通用唯一识别码，是一个软件建构的标准，目的是让分布式系统中的所有元素都能有唯一的辨识信息。

6.使用expect附带的mkpasswd

usage: mkpasswd [args] [user]
  where arguments are:
    -l #      (length of password, default = 9)  密码长度
    -d #      (min # of digits, default = 2)  数字的数量
    -c #      (min # of lowercase chars, default = 3)  小写字母的数量
    -C #      (min # of uppercase chars, default = 2)  大写字母的数量
    -s #      (min # of special chars, default = 1)  特殊字符的数量
    -v        (verbose, show passwd interaction)
    -p prog   (program to set password, default = passwd)
	
[root@codis-178 ~]# mkpasswd -l 16 -d 4 -c 4 -C 4 -s 4
04r-v3"zIa5G??LC
[root@codis-178 ~]# mkpasswd -l 16 -d 4 -c 4 -C 4 -s 1
HHldb8zZJ%0mh00r
[root@codis-178 ~]# mkpasswd -l 16 -d 4 -c 4 -C 4 -s 4
D#uC{1#17kVyjM2

总结

统一格式化：使用md5sum|cut -c 2-10

三、select循环

1.select语法

select 变量名 [ in 菜单取值列表 ]
do
	指令...
done

2.select循环的作用

创建菜单

3.实现

[root@codis-178 ~]# cat 11_10.sh 
#!/bin/bash
select name in oldboy oldgirl tingting
do
	echo $name
done
[root@codis-178 ~]# sh 11_10.sh 
1) oldboy
2) oldgirl
3) tingting
#? 1
oldboy
#? 2
oldgirl
#? 3
tingting

调整select菜单项的默认提示符及利用select变量打印数字序号

[root@codis-178 ~]# cat 11_10_1.sh 
#!/bin/bash
PS3="please select a num from menu:"
select name in oldboy oldgirl tingting
do
	echo -e "I guess you selected the menu is:
 $REPLY) $name"
done
[root@codis-178 ~]# sh 11_10_1.sh 
1) oldboy
2) oldgirl
3) tingting
please select a num from menu:1
I guess you selected the menu is:
 1) oldboy
please select a num from menu:2
I guess you selected the menu is:
 2) oldgirl
please select a num from menu:3
I guess you selected the menu is:
 3) tingting