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，用于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。# wget http://www.tildeslash.com/monit/dist/monit-4.8.2.tar.gz

# tar -zcvf monit-4.8.2.tar.gz
# cd monit-4.8.2

# ./configure
# make


# make install

# cp monitrc /etc/monitrc

By default monit is located at  /usr/local/bin/monit

centos /etc/monitrc
Debian  /etc/monit/monitrc

# vi /etc/monitrc

set daemon  120
set logfile syslog facility log_daemon

set mailserver  mail.cyberciti.biz
set mail-format { from: alert@nixcraft.in
subject: $SERVICE $EVENT at $DATE
message: Monit $ACTION $SERVICE at $DATE on $HOST: $DESCRIPTION.
}

check process lighttpd with pidfile /var/run/lighttpd.pid
group lighttpd
start program = "/etc/init.d/lighttpd start"
stop program = "/etc/init.d/lighttpd stop"
if failed host 75.126.43.232 port 80
protocol http then restart
if 5 restarts within 5 cycles then timeout

check process mysqld with pidfile /var/run/mysqld/mysqld.pid
group database
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
if 5 restarts within 5 cycles then timeout

check process sshd with pidfile /var/run/sshd.pid
start program "/etc/init.d/sshd start"
stop program "/etc/init.d/sshd stop"
if failed host 127.0.0.1 port 22 protocol ssh then restart
if 5 restarts within 5 cycles then timeout


Replace IP address 127.0.0.1 with your actual IP address. If you are using Debian just start monit:
# /etc/init.d/monit start

If you are using  Red Hat Enterprise Linux , start monit from /etc/inittab file:
Open /etc/inittab file:
# vi /etc/inittab
Append following line:
mo:2345:respawn:/usr/local/bin/monit -Ic /etc/monitrc

Now start monit:
# inittab -q

You can verify that monit is started from /var/log/message log file:
# tail -f /var/log/message Output:

Nov 21 04:39:21 server monit[8759]: Starting monit daemon
Nov 21 04:39:21 server monit[8759]: Monit started

If lighttpd died, you will see something as follows in log file:

Nov 21 04:45:13 server monit[8759]: 'lighttpd' process is not running
Nov 21 04:45:13 server monit[8759]: 'lighttpd' trying to restart
Nov 21 04:45:13 server monit[8759]: 'lighttpd' start: /etc/init.d/lighttpd

You may use monit to monitor daemon processes or similar programs running on localhost or started from /etc/init.d/ location such as
=> Apache Web Server
=> SSH Server
=> Postfix/Sendmail MTA
=> MySQL etc