【shell】shell编程总结

　　总结一下在写shell脚本时的常见注意事项:

1.shell脚本中的命令最好用命令的全路径，如果不知道全路径可以用which cmd查找命令的全路径。

2.shell脚本中定义环境变量用export xxx=/dir1/dir2.....

3.shell脚本中取变量所以变量前都需加$,或者最好是${变量}

4.掌握常见的if、for、case语法的使用方法

5.shell脚本中最好写清楚注释

6. shell脚本中善于使用函数

7.用 $? 来判断上一个shell命令的执行结果，返回值是0代表正常结束，返回值是其他则代表不正常

8. 将一些命令的执行结果重定向到/dev/null，错误结果也需要重定向到/dev/null (/dev/null是linux的无底洞，我们丢进去的东西就都找不回来了)

9.善于使用ps 加grep命令判断一些服务是否启动，根据是否有相应的进程判断对应的服务是否启动。

10 善于使用awk命令提取一些需要的信息

killUser.sh　　(输入登录的用户名，然后强制退出用户的脚本)

#!/bin/bash
#input username and kill relactive process for kill user
echo "please input username for kill"
read username
#if username is root ,exit
if [ ${username} = 'root' ]
        then
        echo "root can not kill"
        exit
fi
#get user PID
PID=`/usr/bin/ps -aux | /usr/bin/grep qlq | /usr/bin/awk '$1="qlq" {print $2}'`
for killpid in $PID
do
        kill - $killpid
done
echo "killed ok!"

tomcat.sh    (测试tomcat服务是否启动，开启、关闭tomcat)

#!/bin/bash
#chkconfig:
#description:tomcat
#input(start stop status) to operate tomcat service
#start funciton(start tomcat service use /opt/apache-tomcat/apache-tomcat-7.0./bin/start.sh)
export CATALINA_HOME=/opt/apache-tomcat/apache-tomcat-7.0.
start(){
        /usr/bin/sh "${CATALINA_HOME}"/bin/startup.sh
        if [ "$?" != "" ]
        then
                echo "service is not success start"
        else
                echo "service is success start"

                                                        fi
        exit
}
#stop function
stop(){
        /usr/bin/sh "${CATALINA_HOME}"/bin/shutdown.sh
        if [ "$?" != "" ]
        then
                echo "service is not success stop"
        else
                echo "service is success stop"

                                                        fi
}
#status function
status(){
        /usr/bin/ps -le | /usr/bin/grep java >/dev/null > /dev/null
        if [ "$?" != "" ]
        then
                echo "service is not start"
        else
                echo "service is running"

                                                fi
}
#read input and dispose function
input=${}
case ${input} in
start)
        start
        ;;
stop)
        stop
        ;;
status)
        status
        ;;
*)
        echo "please use {start to start tomcat,stop to stop tomcat,status to read tomcat status!}"
esac

webmin.ssh  (测试webmin服务是否启动、开启、关闭webmin服务)

#!/bin/bash
#start webmin service
start()
{
/etc/webmin/start >/dev/null > /dev/null
if [ $? = '' ]
        then
        echo "webmin is success start"
fi
}

#stop webmin service
stop()
{
/etc/webmin/stop > /dev/null > /dev/null
if [ $? = '' ]
        then
        echo "webmin is success stop"
fi
}

#status webmin
status()
{
   /usr/bin/netstat -ano | /usr/bin/grep  > /dev/null
   if [ $? != '' ]
        then
        echo "webmin is not start"
   else
        echo "webmin is running"
    fi
}

########read input##############
str=$
if [ ${str} = 'start' ]
        then
        start
elif [ ${str} = 'stop' ]
        then
        stop
elif [ ${str} = 'status' ]
        then
        status
else
        echo "please use {start,stop,status}"
fi

addUserBatch.sh     (批量添加用户的脚本)

#!/bin/bash
#adduser batch
echo "please input username:"
read username
echo "please input number to create:"
read number
#start to create user
for(( i=;i<="${number}";i++ ))
do
        /usr/sbin/adduser "${username}${i}" > /dev/null > /dev/null
done
#add finished
echo "add OK!"
echo "please input passwd for users"
read password
for(( i=;i<="${number}";i++ ))
do
        /usr/sbin/usermod -p "${password}" "${username}${i}"  > /dev/null > /dev/null
done

delUserBatch.sh      (批量删除用户的脚本)

#!/bin/bash
#delete user batch
echo "please input username word to delete"
read word
#get All users like word*
users=`/usr/bin/grep ${word} /etc/passwd | awk -F: -v word1=${word} 'index($1,word1)>0 {print $1}'`
if [ "${users}" = '' ]
 then
        echo "user is does not exist!"
        exit
fi
for username in ${users}
do
        /usr/sbin/userdel -rf ${username} > /dev/null >/dev/null
done
if [ "" = "$?" ]
        then
        echo "delete ok!"
else
        echo "delete failed!"
fi