爱站程序员基地一、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#variblesnginx_install_doc=/usr/local/nginxnginxd=$nginx_install_doc/sbin/nginxpid_file=$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/functionselseecho \"not found file /etc/init.d/functions\"exitfiif [ -f $pid_file ];thennginx_process_id=`cat $pid_file`nginx_process_num=`ps aux |grep $nginx_process_id | grep -v grep|wc -l`fi#functionstart () {#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 ];thenecho \"nginx running...\"elseif [ -f $pid_file ]&&[ $nginx_process_num -lt 1 ];thenrm -f $pid_fileecho \" nginx start `daemon $nginxd` \"fiecho \" nginx start `daemon $nginxd` \"fi}stop () {if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];thenaction \"nginx stop\" killall -s QUIT $nginxd#rm -f $pid_fileelseaction \"nginx stop\" killall -s QUIT $nginxd 2>/dev/nullfi}restart () {stopsleep 1start}reload () {if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];thenaction \"nginx reload\" killall -s HUP nginxelseaction \"nginx reload\" killall -s HUP nginx 2>/dev/nullfi}status () {if [ -f $pid_file ]&&[ $nginx_process_num -ge 1 ];thenecho \"nginx running...\"elseecho \"nginx stop\"fi}#callablecase $1 instart) 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 statusnginx running...[root@localhost test20210731]# service nginxd stopStopping nginxd (via systemctl): Warning: nginxd.service changed on disk. Run \'systemctl daemon-reload\' to reload units.[ 确定 ][root@localhost test20210731]# service nginxd statusnginx stop[root@localhost test20210731]# service nginxd startStarting nginxd (via systemctl): [ 确定 ][root@localhost test20210731]# service nginxd statusnginx running...
