shell脚本练习

实现传入进程pid，查看对应进程/proc下cpu、内存指标

#!/bin/bash
read -p "pid number:" a
pid=`ps aux | awk '{print $2}'|grep -w $a`
if [ ! $pid ];then
        echo "input is wrong"
else
        echo "Mem:`cat /proc/$pid/status |egrep  ^Vm`"
        echo "CPU:`ps -eo pid,%cpu|egrep -w $pid`"
fi

实现每分钟检查一个主机端口是否存活（使用nmap），如果检查到端口不在线，sleep 10s，如果三次都不存在，记录到日志

#!/bin/bash
read -p "please input ip eg(192.168.1.1):" ip
read -p "need check port:" port
for i in {1..3};do
  nmap -sS $ip | awk '{print $1}'|egrep  [[:digit:]]|awk -F/ '{print $1}'|grep -w $port &> /dev/null 
if [ `echo $?` -ne 0 ];then
                sleep 2
        echo "$ip $port is not online">/root/check.txt && echo "Wrong!please cat /root/check.txt"
else
        echo "$ip $port is online"
fi
done    
crontab  -e -uroot
*/1 * * * *  /root/port.sh

判断参数文件是否为sh后缀的普通文件，如果是，添加所有人可执行权限，否则提示用户非脚本文件

#!/bin/bash
if [ ! -f $1 ];then
        echo "$1 is wrong(not exist or not sh$ file)"
elif [[ $1 =~ .*sh$ ]];then
        chmod +x $1; 
        echo "add x power over"
fi

实现禁止和允许所有普通用户登录系统

#!/bin/bash
read -p "Do you want to lock usually users:yes or no" y
if [[ $y == yes ||  $y == y ]];then
        touch  /etc/nologin
        echo "locked"
else 
        rm -rf /etc/nologin
        echo "opened"
fi

计算/etc/passwd文件中第10个和第20个用户的ID之和

#!/bin/bash
a=`getent passwd| awk -F: '{print $3}'|sed  -n '10p'`
b=`getent passwd| awk -F: '{print $3}'|sed  -n '20p'`
c=`getent passwd| awk -F: '{print $4}'|sed  -n '10p'`
d=`getent passwd| awk -F: '{print $4}'|sed  -n '20p'`
echo "sum.uid=$[a+b]"
echo "sum.gid=$[c+d]"