How to: Use chkconfig, or keeping your services running on a new run level

OK, so I didn't take my own advice and made sure that all of my services where set to the run on the correct run levels before I switched run levels and rebooted the servers.

chkconfig is a command-line tool for updating the /etc/rc[0-6].d directories.

So I ran chkconfig --list | more to see what was running and in what run levels. Next I ran chkconfig --levels 235 service on to tell the service to start when it enters that run level. For example:

chkconfig --levels 235 named on

Now since I have already rebooted the server, and I know this service didn't start on it's own I had to:

service named start

If I had been smarter and done all of this before hand but wanted to see if named was running or not I would have run:

service named status

I understand that all of this is basics, but some people learn from others mistakes, so hopefully I can save one person from doing the same thing.

Other useful chkconfig switches:

chkconfig --help (Used to display the help dialog)

chkconfig --add [Service Name] (chkconfig --add mysqld) (Adds a service to the chkconfig list)

chkconfig --del [Service Name] (chkconfig --del mysqld) (Deletes a service from the chkconfig list)

chkconfig --level [2,3,4,5][Service Name][on, off, reset] (chkconfig --levels 235 httpd on)(Sets the run levels a service should start in.)

chkconfig can also manage xinetd scripts via /etc/xinetd.d.

Oh, and while you are at it run chkconfig --list | more to review what services are running on your server, you might be suprised. For instance I had bluetooth support running, but not one computer in my company has bluetooth support, so I disabled it (chkconfig --levels 2345 off) and (service bluetooth stop).