My Apache Experience 2

When I ran

/etc/init.d/apache2 restart

but the simple error was displayed like below

ERROR: apache2 failed to start

Finally, I found a way to find out the failure reason,

/etc/init.d/apache2 -d -v start

From the console output the progress message, 

+ '[' 10 -lt 15 ']'

+ '[' -e /var/run/apache2.pid ']'

+ sleep 1

the startup program will check /var/run/apache2.pid existed or not,

but from the configuration file

/etc/apache2/modules.d/00_mpm.conf

the pid file is stored in /run/apache2.pid

so I modified the configuration file to update the pid file to /var/run.

Retry again /etc/init.d/apache2 and finally it is ok right now.

 * Stopping apache2 ...                                                                                         [ ok ]

 * Starting apache2 ...                                                                                         [ ok ]

Reference:

http://wonkabar.org/2012/09/10/gentoo-openrc-apache-and-monit-proper-starting-and-stopping/