section.arch.shell.xml

<?xml version="1.0" encoding="UTF-8"?>
<section id="shell">
	<title>Shell 高级编程</title>
	<section>
		<title>递归调用</title>
		<para>不懂递归不算是合格的程序员</para>
		<para>递归调用是一种特殊的嵌套调用，是一个函数在它的函数体内调用它自身称为递归调用。这种函数称为递归函数。</para>
		<screen>
		<![CDATA[
#!/bin/bash
########################################
# Author: Neo <netiller@msn.com>
# Home : http://netkiler.github.io
# Project: https://github.com/oscm/shell
########################################
domain=$1
########################################
function include(){
	txt=$1
	for host in $(echo $txt | egrep -o "include:(.+) ")
	do
		txt=$(dig $(echo $host | cut -d":" -f2) txt | grep "v=spf1")
		echo $txt;
		if [ "$(echo $txt | grep "include")" ]; then
			include "$txt"
		fi
	done
}
function main(){
	spf=$(dig ${domain} txt | grep "v=spf1")
	echo $spf

	if [ "$(echo $spf | grep "include")" ]; then
		include "$spf"
	fi
}

main $domain
		]]>
		</screen>
		<para>运行上面的程序</para>
		<screen>
		<![CDATA[
$ bash spf.sh 163.com
163.com. 6878 IN TXT "v=spf1 include:spf.163.com -all"
spf.163.com. 16991 IN TXT "v=spf1 include:a.spf.163.com include:b.spf.163.com include:c.spf.163.com include:d.spf.163.com -all"
a.spf.163.com. 8001 IN TXT "v=spf1 ip4:220.181.12.0/22 ip4:220.181.31.0/24 ip4:123.125.50.0/24 ip4:220.181.72.0/24 ip4:123.58.178.0/24 ip4:123.58.177.0/24 ip4:113.108.225.0/24 ip4:218.107.63.0/24 ip4:123.58.189.128/25 -all"
b.spf.163.com. 10131 IN TXT "v=spf1 ip4:176.34.21.58 ip4:176.34.53.178 ip4:121.195.178.48/28 ip4:223.252.213.0/24 -all"
c.spf.163.com. 17199 IN TXT "v=spf1 ip4:223.252.206.0/24 ip4:43.230.90.0/27 -all"
d.spf.163.com. 17615 IN TXT "v=spf1 ip4:123.126.65.0/24 ip4:106.2.88.0/24 ip4:220.181.97.0/24 ip4:180.150.142.123 ip4:180.150.142.124 ip4:180.150.154.88 ip4:180.150.154.92 ip4:180.150.154.93 ip4:103.251.128.69 -all"
		]]>
		</screen>
	</section>
	<section>
		<title>实现守护进程</title>
		<para>无论是C语言还是php/python/perl 通过fork命令实现守护进程，让当前程序进入后台运行，这种手段常常用于服务器软件。</para>
		<para>启用 shell 解决重复运行问题，记录PID以便可以停止Shell运维</para>
		<screen>
		<![CDATA[
#!/bin/bash
##############################################
# $Id$
# Author: Neo <netiller@msn.com>
# Home : http://netkiler.github.io
# Project: https://github.com/oscm/shell
##############################################
NAME=info
BASEDIR='/www'
PROG=$BASEDIR/bin/$(basename $0)
LOGFILE=/var/tmp/$NAME.log
PIDFILE=/var/tmp/$NAME.pid
##############################################
PHP=/usr/local/webserver/php/bin/php
##############################################
#echo $$
#echo $BASHPID
function start(){
	if [ -f "$PIDFILE" ]; then
		echo $PIDFILE
		exit 2
	fi

	for (( ; ; ))
	do
		cd $BASEDIR/crontab/
		$PHP readfile.php > $LOGFILE
		$PHP chart_gold_silver_xml.php > /dev/null
		sleep 60
	done &
	echo $! > $PIDFILE
}
function stop(){
  	[ -f $PIDFILE ] && kill `cat $PIDFILE` && rm -rf $PIDFILE
}

case "$1" in
  start)
  	start
	;;
  stop)
  	stop
	;;
  status)
  	ps ax | grep chart.xml | grep -v grep | grep -v status
	;;
  restart)
  	stop
	start
	;;
  *)
	echo $"Usage: $0 {start|stop|status|restart}"
	exit 2
esac

exit $?
		]]>
		</screen>
	</section>

	<section>
		<title>进程间通信</title>
		<para>进程间通信就是在不同进程之间传播或交换信息。</para>
		<para>脚本具有黑白名单功能，一个进程专门负责采集数据，另一个进程专门负责处理由第一个进程发送过来的数据。</para>
		<screen>
		<![CDATA[
#!/bin/bash           
########################################  
# Homepage: http://netkiller.github.io  
# Author: neo <netkiller@msn.com>  
########################################  
BLACKLIST=/tmp/BLACKLIST.lst  
PIPE=/tmp/pipe  
pidfile=/tmp/firewall.pid  
KEYWORD=XXDD0S  
ACCESSLOG=/www/logs/www.example.com/access.$(date +'%Y-%m-%d').log  
########################################  
if [ -z $1 ]; then  
    echo "$0 clear|fw|collect|process|close"  
fi
  
if [ "$1" == "clear" ]; then  
    rm -rf $BLACKLIST  
    rm -rf $PIPE  
    echo "Clear OK!!!"  
fi
  
if [ "$1" == "close" ]; then  
        kill `cat $pidfile`  
    echo > $pidfile  
fi
  
if [ ! -f $BLACKLIST ]; then  
    touch $BLACKLIST  
fi  
  
if [ ! -e $PIPE ]; then  
    mkfifo $PIPE  
fi  
  
if [ "$1" == 'fw' ]; then  
    iptables -A OUTPUT -p tcp --dport 2049 -j REJECT  
    iptables -A OUTPUT -p tcp -m multiport --dports 22,21 -j REJECT  
fi  
  
if [ "$1" == "collect" ]; then  
    killall tail
    for (( ; ; ))  
    do  
        tail -f $ACCESSLOG | grep $KEYWORD | cut -d ' ' -f1 > $PIPE  
    done &  
    echo $! > $pidfile  
fi  
  
if [ "$1" == "process" ]; then  
for (( ; ; ))  
do  
    while read line   
    do  
        grep $line ${BLACKLIST}
        if [ $? -eq 1 ] ; then  
            echo $line >> ${BLACKLIST}
            iptables -I INPUT -p tcp --dport 80 -s $line -j DROP      
        fi  
    done < $PIPE  
done &  
echo $! >> $pidfile  
fi  
		]]>
		</screen>
		<para>首先启动第一个进程，准备接收数据</para>
		<screen>
		<![CDATA[
# ipfw process
		]]>
		</screen>
		<para>然后启动第二个进程，发送采集数据</para>
		<screen>
		<![CDATA[
# ipfw collect
		]]>
		</screen>
		<para>这个程序使用管道作为进程见通信手段，所以只能在一个系统下运行，如果改为Socket通信就可以实现跨服务器数据处理</para>
	</section>
	
</section>