linux-shell script

syntax

 1. The basic layout

#! /bin/bash

 2. Notice

  2.1 Login execute commands on other nodes using ssh sh, other node of the console feedback information is also in the implementation of the nodes in the console print out sh

 3. into the reference

Identifier	desc
$*	It refers to all input
$index	The first index parameter
$#	The number of parameters

 4. Variable

Assign values ​​to variables, quotes

 5. Process control

  5.1 Select

if [ $a == $b ]
then
   echo "a is equal to b"
elif [ $a -gt $b ]
then
   echo "a is greater than b"
elif [ $a -lt $b ]
then
   echo "a is less than b"
else
   echo "None of the condition met"
fi

  5.2 cycle

for i in {1..5}
do
    echo $i
done


for i in 5 6 7 8 9
do
    echo $i
done


for FILE in $HOME/.bash*
do
   echo $FILE
done
break  #跳出所有循环
break n  #跳出第n层f循环
continue  #跳出当前循环

COUNTER=0
while [ $COUNTER -lt 5 ]
do
    COUNTER=`expr $COUNTER + 1`
    echo $COUNTER
done

case $变量名 in
"值 1")
;;
如果变量的值等于值1，则执行程序1，值
"值 2")
如果变量的值等于值2，则执行程序2
…省略其他分支…
;;
*)
如果变量的值都不是以上的值，则执行此程序
;;
esac

 6. Functions

  shell functions defined in three ways, three ways equivalent

		f_name(){……}
		function f_name{……}
		function f_name(){……}

  Parameter passing, brackets need not pay attention to the time parameter is defined in the body of the function can be used directly by $ num. 注意，函数中的\$num和脚本的\$num不同.

test(){
    echo $1  #接收第一个参数
    echo $2  #接收第二个参数
    echo $3  #接收第三个参数
    echo $#  #接收到参数的个数
    echo $*  #接收到的所有参数
}

test aa bb cc

  If you want to use this function in addition to the script,EXPORT 函数名

  When you call, direct函数名 arg1 arg2

 7. redirection and append

$echo result > file  #将结果写入文件，结果不会在控制台展示，而是在文件中，覆盖写
$echo result >> file  #将结果写入文件，结果不会在控制台展示，而是在文件中，追加写

Common Commands

1. echo
   the contents of the output lines with or without quotation marks
2. ssh
3. sleep

example

 1.CDH start and stop

#! /bin/bash

#1 判断参数个数，如无参数输入，直接退出
argscount=$#
if((argscount == 0));
then
    echo ============================no args============================
    exit;
fi

#2 函数封装
function start(){
    echo ============================启动CDH:begin============================

    #   判断mysql是否启动，如果没启动，先启动mysql
    mysqlPortStat=`netstat -anp | grep 3306 | wc -l`
    if [ $mysqlPortStat == 0 ]
    then
        ssh node105 systemctl start mysqld
    fi
    echo "mysql 已经启动"

    #   启动CDH
    sleep 1s;

    ssh node105 /opt/cm-5.16.2/etc/init.d/cloudera-scm-server $1

    for((host=105;host < 108;host++));
    do
        ssh node$host /opt/cm-5.16.2/etc/init.d/cloudera-scm-agent $1
    done
    # 获取当前前后时间的从1970UTC为止的秒数
    start_datetime=`date +%s`
    # CDH启动最起码需要等待30s，所以先sleep 30s; 然后再轮循
    sleep 30s;

    #   监控7180端口，如果监听到数量大于0，说明CDH启动完成
    CDHPortCount=`netstat -anp | grep 7180 | wc -l`
    while [ $CDHPortCount == 0 ]
    do
        CDHPortCount=`netstat -anp | grep 7180 | wc -l`
        sleep 5s;
    done

    end_datetime=`date +%s`
    echo $end_datetime

    echo ============================启动CDH:successed,等待$[end_datetime-start_datetime]s============================
}

function stop(){
    echo ============================停止CDH:begin============================
    for((host=105;host < 108;host++));do
        ssh node$host /opt/cm-5.16.2/etc/init.d/cloudera-scm-agent $1
    done

    ssh node105 /opt/cm-5.16.2/etc/init.d/cloudera-scm-server $1
    echo ============================停止CDH:successed============================
}

function restart(){
    # 判断mysql是否启动，如果没启动，先启动mysql
    mysqlPortStat=`netstat -anp | grep 3306 | wc -l`
    if [ $mysqlPortStat == 0 ]
    then
        ssh node105 systemctl start mysqld
    fi
    echo "mysql 已经启动"
    #
    echo ============================重启CDH:begin============================
    for((host=105;host < 108;host++));
    do
        ssh node$host /opt/cm-5.16.2/etc/init.d/cloudera-scm-agent $1
    done

    ssh node105 /opt/cm-5.16.2/etc/init.d/cloudera-scm-server $1
    echo ============================重启CDH:successed============================
}

#3 根据输入参数执行相应操作
case $1 in
    "start")
        start $1;
    ;;
    "stop")
        stop $1;
    ;;
    "restart")
        restart $1;
    ;;
esac

 2.rrsync distribution script

#!/bin/bash
#1 获取输入参数个数，如果没有参数，直接退出
pcount=$#
if((pcount==0)); then
echo no args;
exit;
fi

#2 获取文件名称
p1=$1
fname=`basename $p1`
echo fname=$fname

#3 获取上级目录到绝对路径
pdir=`cd -P $(dirname $p1); pwd`
echo pdir=$pdir

#4 获取当前用户名称
user=`whoami`

#5 循环
for((host=105; host<108; host++)); do
	echo ------------------- node$host --------------
	rsync -rvl $pdir/$fname $user@node$host:$pdir
done

 3.xcall uniform implementation of the script

#! /bin/bash

for i in node105 node106 node107
do
	echo --------- $i ----------
	ssh $i "$*"
done