Shell编程实战-函数知识

总结

方法

01、函数语法：

function 函数名() {
	指令...
	return n
}

02、简化语法：

函数名() {
	指令...
	return n
}

03、函数调用：

#!/bin/bash
oldboy(){
	echo "I am oldboy."
}
function oldgirl(){
	echo "I am oldgirl."
}
oldboy
oldgirl

04、检查Web URL是否正常：cat 8_6.sh

#!/bin/sh
. /etc/init.d/functions
function usage(){
	echo $"usage:$0 url"
	exit 1
}
function check_url(){
	wget --spider -q -o /dev/null --tries=1 -T 5 $1
	if [ $? -eq 0 ];then
		action "$1 is yes." /bin/true
	else
		action "$1 is no." /bin/false
	fi
}
function main(){
	if [ $# -ne 1 ];then
		usage
	fi
	check_url $1
}
main $*
----------
sh 8_6.sh www.baidu.com

05、优化系统脚本：cat sys_opt.sh

#!/bin/bash 
# author:oldboy
# qq:31333741
#set env
export PATH=$PATH:/bin:/sbin:/usr/sbin
# Require root to run this script.
if [ "$UID" != "0" ];then
	echo "Please run this script by root."
	exit 1
fi
#define cmd var
SERVICE=`which service`
CHKCONFIG=`which chkconfig`
function mod_yum(){
	#modify yum path
	if [ -e /etc/yum.repos.d/CentOS-Base.repo ];then
	mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup&&\
	wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
	fi
}

function close_selinux(){
	#1.close selinux
	sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
	#grep SELINUX=disabled /etc/selinux/config
	setenforce 0 &>/dev/null
	#getenforce
}
function close_iptables(){
	#2.close iptables
	/etc/init.d/iptables stop
	/etc/init.d/iptables stop
	chkconfig iptables off 
}
function least_service(){
	#3.least service startup
	chkconfig|awk '{print "chkconfig",$1,"off"}'|bash
	chkconfig|egrep "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"on"}'|bash
	#export LANG=en
	#chkconfig --list|grep 3:on
}
function adduser(){
	#4.add oldboy and sudo
	if [ `grep -w oldboy /etc/passwd|wc -l` -lt 1 ];then
		useradd oldboy
		echo 123456|passwd --stdin oldboy
		\cp /etc/sudoers /etc/sudoers.ori
		echo "oldboy  ALL=(ALL) NOPASSWD: ALL " >>/etc/sudoers
		tail -1 /etc/sudoers
		visudo -c &>/dev/null
	fi
}
function charset(){
	#5.charset config
	cp /etc/sysconfig/i18n /etc/sysconfig/i18n.ori
	echo 'LANG="zh_CN.UTF-8"'  >/etc/sysconfig/i18n
	source /etc/sysconfig/i18n
	#echo $LANG
}
function time_sync(){
	#6.time sync.
	cron=/var/spool/cron/root
	if [ `grep -w "ntpdate" $cron|wc -l` -lt 1 ];then
		echo '#time sync by oldboy at 2010-2-1' >>$cron
		echo '*/5 * * * * /usr/sbin/ntpdate time.nist.gov>/dev/null 2>&1'>>$cron
		crontab -l
	fi
}
function com_line_set(){
	#7.command set.
	if [ `egrep "TMOUT|HISTSIZE|ISTFILESIZE" /etc/profile|wc -l` -lt 3  ];then
		echo 'export TMOUT=300' >>/etc/profile
		echo 'export HISTSIZE=5' >>/etc/profile
		echo 'export HISTFILESIZE=5' >>/etc/profile
		. /etc/profile
	fi
}
function open_file_set(){
	#8.increase open file.
	if [ `grep 65535 /etc/security/limits.conf|wc -l` -lt 1 ];then
		echo '*           -      nofile        65535 '>>/etc/security/limits.conf
		tail -1 /etc/security/limits.conf
	fi
}
function set_kernel(){
	#9.kernel set.
	if [ `grep kernel_flag /etc/sysctl.conf|wc -l` -lt 1 ];then
		cat >>/etc/sysctl.conf</dev/null
}
function update_linux(){
	#10.upgrade linux.
	if [ `rpm -qa lrzsz nmap tree dos2unix nc|wc -l` -le 3 ];then
		yum install lrzsz nmap tree dos2unix nc -y
		#yum update -y
	fi
}
main(){
	mod_yum
	close_selinux
	close_iptables
	least_service
	adduser
	charset
	time_sync
	com_line_set
	open_file_set
	set_kernel
	init_ssh
	update_linux
}
main 

06、优化结果：

cat check_opt.sh
#!/bin/bash
################################################
#this scripts is created by oldboy
#oldboy QQ:31333741
#blog:http://oldboy.blog.51cto.com
################################################
#set env
export PATH=$PATH:/bin:/sbin:/usr/sbin
# Require root to run this script.
if [ "$UID" != "0" ]; then
	echo "Please run this script by root."
	exit 1
fi
# Source function library.
. /etc/init.d/functions
function check_yum(){
	Base=/etc/yum.repos.d/CentOS-Base.repo
	if [ `grep aliyun $Base|wc -l` -ge 1 ];then
		action "$Base config" /bin/true
	else
		action "$Base config" /bin/false
	fi
}
function check_selinux(){
	config=/etc/selinux/config
	if [ `grep "SELINUX=disabled" $config|wc -l ` -ge 1 ];then
		action "$config config" /bin/true
	else
		action "$config config" /bin/false
	fi
}
function check_service(){
	export LANG=en
	if [ `chkconfig|grep 3:on|egrep "crond|sshd|network|rsyslog|sysstat"|wc -l` -eq 5 ];then
		action "sys service init" /bin/true
	else
		action "sys service init" /bin/false
	fi
}
function check_open_file(){
	limits=/etc/security/limits.conf
	if [ `grep 65535 $limits|wc -l` -eq 1 ];then
		action "$limits" /bin/true
	else
		action "$limits" /bin/false
	fi
}
main(){
	check_yum
	check_selinux
	check_service
	check_open_file
}
main

07、rsyncd服务启动：

cat /etc/init.d/rsyncd1
#!/bin/bash
# chkconfig: 2345 20 80
# description: Rsyncd Startup scripts by oldboy.
. /etc/init.d/functions
function usage(){
	echo $"usage:$0 {start|stop|restart}"
	exit 1
}
function start(){
	rsync --daemon
	sleep 1
	if [ `netstat -lntup|grep rsync|wc -l` -ge 1 ];then
		action "rsyncd is started." /bin/true
	else
		action "rsyncd is started." /bin/false
	fi
}
function stop(){
	killall rsync &>/dev/null
	sleep 2
	if [ `netstat -lntup|grep rsync|wc -l` -eq 0 ];then
		action "rsyncd is stopped." /bin/true
	else
		action "rsyncd is started." /bin/false
	fi
}
function main(){
	if [ $# -ne 1 ];then
		usage
	fi
	if [ "$1" = "start" ];then
		start
	elif [ "$1" = "stop" ];then
		stop
	elif [ "$1" = "restart" ];then
		stop
		sleep 1
		start
	else
		usage
	fi
}
main $*
----------
/etc/init.d/rsyncd1 start