monit监控服务进程
Monit是一款功能非常丰富的进程、文件、目录和设备的监测软件，适用于Linux/Unix平台。 它可以自动修复那些已经停止运作的程序,特使适合处理那些由于多种原因导致的软件错误.
安装monit，最好使用yum安装，使用编码包编译有问题
yum install -y monit
编辑配置文件
vim /etc/monit.conf
修改检查时间为3秒以及id文件路径和开启日志
set daemon 3 # check services at 2-minute intervals
set idfile /tmp/id
# set logfile syslog facility log_daemon
set logfile /var/log/monit.log
mkdir /var/monit
chmod -R 750 /var/monit/
然后启动monit
/etc/init.d/monit start
进入配置目录
cd /etc/monit.d/
添加mysql服务监控
vi mysql
check process mysql with pidfile /usr/local/mysql/var/test.kuaidihelp.com.pid
start program = "/etc/init.d/mysqld start"
stop program = "/etc/init.d/mysqld stop"
if failed host 127.0.0.1 port 3306 then restart
注意以上粗体字部分，是需要修改的。
添加http服务监控
vi http
check process http with pidfile /usr/local/apache/logs/httpd.pid
start program = "/etc/init.d/httpd start"
stop program = "/etc/init.d/httpd stop"
if failed host 127.0.0.1 port 80 then restart
重启服务
/etc/init.d/monit restart
测试关闭进程，然后查看进程是否启动
如果需要监控tomcat，需要开启tomcat的pid文件，默认是没有的
修改脚本，添加蓝色部分
vi /usr/local/tomcat/bin/catalina.sh
# CATALINA_PID (Optional) Path of the file which should contains the pid
# of catalina startup java process, when start (fork) is used
CATALINA_PID=/usr/local/tomcat/tomcat.pid
重启tomcat
/usr/local/tomcat/bin/shutdown.sh
/usr/local/tomcat/bin/startup.sh
vi /etc/monit.d/tomcat
check process java with pidfile /usr/local/tomcat/tomcat.pid
start program = "/usr/local/tomcat/bin/startup.sh"
stop program = "/usr/local/tomcat/bin/shutdown.sh"
if failed host 127.0.0.1 port 8080 then restart
重启monit
/etc/init.d/monit restart
测试关闭tomcat，查看tomcat是否启动
否则服务可能没有停止命令，比如rsync，那么只能kill掉，注意不要用killall，用pkill比较好一点。
vi /etc/monit.d/rsync
check process rsync with pidfile /var/run/rsync.pid
start program = "/usr/bin/rsync --daemon"
stop program = "/usr/bin/pkill rsync"
if failed host 127.0.0.1 port 873 then restart
重启monit，注意观察输出的信息，没有Warning信息就说明配置正确。
/etc/init.d/monit restart
注意：
Monit是是根据被监控的进程的pid文件来检测的，如果没有pid文件，是无法使用的。