天天写点shell

本身写了一下小的shell实例，虽然很小，但全部的大的程序都是由小的模块堆积起来的，程序员必定要懂得一种脚本的书写，而我，只会在linux下工做，因此就只能写linux的shell脚本了，呵呵，本文会陆续更新，给本身加油！

1.模拟linux登录shell

vim linux1.sh
#!/bin/bash
echo -n "login:"
read name
echo -n "password:"
read passwd
if [ $name = "tianqi" -a $passwd = "abc123" ];then
echo "the host and password is right!"
else echo "input is error!"
fi
sh linux1.sh
login:tianqi
password:abc123
the host and password is right!
[ec2-user@ip-172-31-21-107 shell]$

友情连接：天天写点shell——read的用法

友情连接：解析shell脚本中if语句的用法

2.比较两个数的大小
 vim number1.sh

#!/bin/bash  
echo "please enter two number"  
read a
read b
if test $a -eq $b
then echo "NO.1 = NO.2"  
elif test $a -gt $b
then echo "NO.1 > NO.2"  
else echo "NO.1 < NO.2"   
fi

 sh number1.sh
please enter two number
5
6
NO.1 < NO.2
[root@tianqi-01 shell]# 

3.查找/root/目录下是否存在该文件

 vim root1.sh

#!/bin/bash
echo "enter a file name:"
read a
if test -e /root/$a
then
        echo "the file is exist!"
else
        echo "the file is not exist!"
fi

 sh root1.sh 
enter a file name:
1.txt
the file is exist!
[root@tianqi-01 shell]# 

4.for循环的使用

 vim for1.sh

#!/bin/bash
clear
for num in 1 2 3 4 5 6 7 8 9 10
do
        echo "$num"
done

 sh for1.sh
1
2
3
4
5
6
7
8
9
10
[root@tianqi-01 shell]# 

5.查看是否当前用户

 vim user1.sh

#!/bin/bash
echo "Please enter a user:"
read a
b=$(whoami)
if test $a = $b
then
        echo "The user is running"
else
        echo "The user is not running"
fi

 sh user1.sh
Please enter a user:
root
The user is running
[root@localhost shell]# 

6.mysql自动备份脚本

#!/bin/bash
#auto backup mysql shell
#tianqi 2018-07-20
#自动备份数据库，并添加任务计划脚本
#定义变量=========================
bak_cmd=/usr/local/mysql/bin/mysqldump
bak_host=localhost
bak_db=tianqi
bak_user=root
bak_pass="123456"
bak_dir=/tmp/mysqlbackup/
bak_date=`date +%F`
if [ $UID -ne 0 ]
then
    echo "必须使用ROOT用户才能执行此脚本"
    exit
fi
if [ ! -d $bak_dir ]
then
    mkdir $bak_dir
    echo "这个目录建立成功"
else
    echo "这个目录已经存在"
fi  
#正式备份
$bak_cmd -u$bak_user -p$bak_pass -h$bak_host -d $bak_db > $bak_dir/tianqi_$bak_date.sql
if [ $? -eq 0 ]
then
    echo "数据库备份成功"
    echo "备份目录：$bak_dir"
else
    echo "数据库备份出错，请检查"
fi
#自动删除30天之前的备份数据
find $bak_dir/ -mtime +30 |xargs rm -rf {} \;
if [ $? -eq 0 ]
then
    echo "删除30天之前的备份数据成功"
else
    echo "命令执行出错，请检查"
fi
#建立自动备份计划任务
grep "back_mysql" /var/spool/cron/root >> /dev/null
if [ $? -ne 0 ]
then
    echo "30 20 * * 5 /root/shell/backup_mysql > /tmp/mysql.log 2>&1" >> /var/spool/cron/root
fi

7.使用shell脚本监控CPU使用率（使用vmstat工具）

#!/bin/bash
if [ `uname` != "Linux" ]
then
    echo "system not linux"
    exit 1
fi

which vmstat &> /dev/null
if [ $? != 0 ]
then
    echo "vmstat command not found, please install package procps"
    exit
fi

cpu_us=`vmstat |sed -n '$'p |awk '{print $13}'`
cpu_sy=`vmstat |sed -n '$'p |awk '{print $14}'`
cpu_id=`vmstat |sed -n '$'p |awk '{print $15}'`
cpu_wa=`vmstat |sed -n '$'p |awk '{print $16}'`
cpu_sum=$[$cpu_us+$cpu_sy]

cpuinfo()
{
    CPU_SUM=$cpu_sum%($CPU_USER=$cpu_us% + $CPU_SYSTEM=$cpu_sy%)
    CPU_IDLE=$cpu_id%
    CPU_WAIT=$cpu_wa
}

cpuinfo

if [ $cpu_sum -gt 90 ]
then
    echo "CPU utilization $cpu_sum" |mail -s "CPU Monitor" 123@qq.com
fi

8.添加10个用户，从user101-user110

1)for用法

#!/bin/bash
for i in `seq 101 110`
do
    useradd user$i
    echo "user$i" |passwd user$i --stdin &> /dev/null
done

2）while用法

#!/bin/bash
i=101
while [ $i -le 110 ]
do
    useradd user$i
    echo "user$i" |passwd user$i --stdin &> /dev/null
done

3）until用法

#!/bin/bash
i=101
until [ $i -gt 110 ]
do
    useradd user$i
    echo "user$i" |passwd user$i --stdin &> /dev/null
done

9.求100之内的偶数和奇数之和

1）for的写法

#!/bin/bash
for i in `seq 0 100`
do
    if [ $[i%2] = 0 ]
    then
        let sum+=$i
    else [ $[i%2] = 1 ]
        let sum1+=$i
    fi
done
echo $sum
echo $sum1

2）while的写法

#!/bin/bash
i=0
while [ $i -le 100 ]
do
    if [ $[i%2] = 0 ]
    then
        let sum+=$i
    else [ $[i%2] = 1 ]
        let sum1+=$i
    fi
    let i++
done
echo $sum
echo $sum1

3）until的写法

#!/bin/bash
i=0
until [ $i -gt 100 ]
do
    if [ $[i%2] = 0 ]
    then
        let sum+=$i
    else [ $[i%2] = 1 ]
        let sum1+=$i
    fi
    let i++
done
echo $sum
echo $sum1

10.打印九九乘法表

1）for的写法

#!/bin/bash
for i in `seq 1 9`
do
    for j in `seq 1 $i`
    do
        echo -n -e "${j}X${i}=$[$j*$i]\t"
    done
    echo
done

2）while的写法

#!/bin/bash
i=1
while [ $i -le 9 ]
do
    j=1
    while [ $j -le $i ]
    do
        echo -n -e "${j}X${i}=$[$j*$i]\t"
        let j++
    done
    echo
    let i++
done

3）until的写法

#!/bin/bash
i=1
until [ $i -gt 9 ]
do
    j=1
    until [ $j -gt $i ]
    do
        echo -n -e "${j}X${i}=$[$j*$i]\t"
        let j++
    done
    echo
    let i++
done

11.打印逆序九九乘法表

1）for的写法

#!/bin/bash
for ((i=9;i>=1;i--))
do
    for ((j=i;j<=9;j++))
    do
        echo -n -e "${i}"X"${j}=$[$j*$i]\t"
    done
    echo
done

2）while的写法

#!/bin/bash
i=9
while [ $i -ge 1 ]
do
    j=$i
    while [ $j -le 9 ]
    do
        echo -n -e "${i}"X"${j}=$[$j*$i]\t"
        let j++
    done
    echo
    let i--
done

3）until的写法

#!/bin/bash
i=9
until [ $i -lt 1 ]
do
    j=$i
    until [ $j -gt 9 ]
    do
        echo -n -e "${i}"X"${j}=$[$j*$i]\t"
        let j++
    done
    echo
    let i--
done

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

友情连接：阿铭Linux