+-
一、函数介绍
将相同功能的代码模块化，使得代码逻辑上比较简单，代码量少，排错容易
函数的优点：
1、代码模块化，调用方便，节省内存
2、代码模块化，代码量少，排错简单
3、代码模块化，可以改变代码的执行顺序
二、函数语法
1、语法一
函数名 () {
代码块
return N
}
2、语法二
function 函数名 {
代码块
return N
}
三、函数应用
#!/usr/bin/bash
#################################
# Author: Mr.white #
# Create_Date: 2021-07-30 22:55:15 #
# Version: 1.0 #
#################################
#定义函数
start () {
echo "Apache start...... [OK]"
#return 0
}
function stop {
echo "Apache stop ...... [FAIL]"
}
#调用函数
start
stop
查询运行结果：
[root@localhost test20210730]# sh fun1.sh
Apache start...... [OK]
Apache stop ...... [FAIL]
四、实战：编写nginx启动管理脚本
#!/usr/bin/bash
#################################
# Author: Mr.white #
# Create_Date: 2021-07-31 01:16:59 #
# Version: 1.0 #
#################################
#nginx seivice manage script
#varibles
nginx_install_doc=/usr/local/nginx
nginxd=$nginx_install_doc/sbin/nginx
pid_file=$nginx_install_doc/logs/nginx.pid
#参考/etc/init.d/network中以下函数库
# Source function library.
if [ -f /etc/init.d/functions ];then
. /etc/init.d/functions
else
echo "not found file /etc/init.d/functions"
exit
fi
if [ -f $pid_file ];then
nginx_process_id=`cat $pid_file`
nginx_process_num=`ps aux |grep $nginx_process_id | grep -v grep|wc -l`
fi
#function
start () {
#判断nginx没有启动直接启动，否则报错已经启动
if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];then
echo "nginx running..."
else
if [ -f $pid_file ]&&[ $nginx_process_num -lt 1 ];then
rm -f $pid_file
echo " nginx start `daemon $nginxd` "
fi
echo " nginx start `daemon $nginxd` "
fi
}
stop () {
if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];then
action "nginx stop" killall -s QUIT $nginxd
#rm -f $pid_file
else
action "nginx stop" killall -s QUIT $nginxd 2>/dev/null
fi
}
restart () {
stop
sleep 1
start
}
reload () {
if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];then
action "nginx reload" killall -s HUP nginx
else
action "nginx reload" killall -s HUP nginx 2>/dev/null
fi
}
status () {
if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];then
echo "nginx running..."
else
echo "nginx stop"
fi
}
#callable
case $1 in
start) start;;
stop) stop;;
restart) restart;;
reload) reload;;
status) status;;
*) echo "USAGE: $0 start|stop|restart|reload|status";;
esac
查看运行结果：
[root@localhost test20210731]# ps aux | grep nginx | grep -v grep [root@localhost test20210731]# sh nginxd.sh #使用帮忙 USAGE: nginxd.sh start|stop|restart|reload|status [root@localhost test20210731]# sh nginxd.sh start #开启进程 nginx start [ OK ] [root@localhost test20210731]# sh nginxd.sh status #查看状态为开启状态 nginx running... [root@localhost test20210731]# sh nginxd.sh start #提示已开启 nginx running... [root@localhost test20210731]# sh nginxd.sh reload #重载进程 nginx reload [ OK ] [root@localhost test20210731]# sh nginxd.sh restart #重启进程 nginx stop [ OK ] nginx start [ OK ] [root@localhost test20210731]# sh nginxd.sh stop #关闭进程 nginx stop [ OK ] [root@localhost test20210731]# sh nginxd.sh status #查看状态为关闭状态 nginx stop [root@localhost test20210731]# sh nginxd.sh stop #提示已经关闭无法再关闭 nginx stop [FAILED] [root@localhost test20210731]# sh nginxd.sh reload #提示已经关闭无法重载 nginx reload [FAILED] [root@localhost test20210731]# sh nginxd.sh restart #提示已经关闭无法重启 nginx stop [FAILED] nginx start [ OK ]
添加到系统服务启动管理
[root@localhost test20210731]# cp -r nginxd.sh /etc/init.d/nginxd [root@localhost test20210731]# chmod 755 /etc/init.d/nginxd [root@localhost test20210731]# service nginxd status nginx running... [root@localhost test20210731]# service nginxd stop Stopping nginxd (via systemctl): Warning: nginxd.service changed on disk. Run 'systemctl daemon-reload' to reload units. [ 确定 ] [root@localhost test20210731]# service nginxd status nginx stop [root@localhost test20210731]# service nginxd start Starting nginxd (via systemctl): [ 确定 ] [root@localhost test20210731]# service nginxd status nginx running...
