Red Hat includes the checkconfig & service utilities to help you manage your start up scripts and save you a lot of typing. This is handy when you’re adding your own services and also in managing the already existing services. chkconfig is available if you want to use it on other distributions that may not come with it – just go to freshmeat.net and look it up. /sbin/service is just a shell script that comes as part of Red Hat’s initscripts package.Without a tool like chkconfig, symbolic links to the scripts in /etc/rc.d/init.d are typically created by hand at the appropriate run levels. This can be messy & difficult to standardize. Also, it is necessary to view the contents of each run level directory to see which services are configured to run. Here’s some ways to use chkconfig: What’s enabled at run level 3?
[root@usr-3 init.d]# chkconfig --list | grep 3:on atd 0:off 1:off 2:off 3:on 4:on 5:on 6:off syslog 0:off 1:off 2:on 3:on 4:on 5:on 6:off sendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:off autofs 0:off 1:off 2:off 3:on 4:on 5:on 6:off network 0:off 1:off 2:on 3:on 4:on 5:on 6:off random 0:off 1:off 2:on 3:on 4:on 5:on 6:off apmd 0:off 1:off 2:on 3:on 4:on 5:on 6:off iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off sshd 0:off 1:off 2:on 3:on 4:on 5:on 6:off portmap 0:off 1:off 2:off 3:on 4:on 5:on 6:off nfs 0:off 1:off 2:off 3:on 4:on 5:on 6:off nfslock 0:off 1:off 2:off 3:on 4:on 5:on 6:off crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off anacron 0:off 1:off 2:on 3:on 4:on 5:on 6:off xinetd 0:off 1:off 2:off 3:on 4:on 5:on 6:off
Enable a service for runlevel 3
[root@usr-3 init.d]# chkconfig wine on [root@usr-3 init.d]# chkconfig --list wine wine 0:off 1:off 2:on 3:on 4:off 5:off 6:off
Disable it
[root@usr-3 init.d]# chkconfig wine off [root@usr-3 init.d]# chkconfig --list wine wine 0:off 1:off 2:off 3:off 4:off 5:off 6:off
Checkconfig reads some lines at the beginning of an rc script to determine what run levels the script should be run at. We’ll use the openssh rc script as our example.
[root@usr-3 init.d]# head -8 sshd #!/bin/bash # # Init file for OpenSSH server daemon # # chkconfig: 2345 55 25 # description: OpenSSH server daemon #
The chkconfig line & description line must go into every script that is to go under the control of chkconfig. The description line seems pretty self-explanatory. the chkconfig line:
# chkconfig: 2345 55 25 | | | | | priority for kill scripts | | | priority for start scripts | run levels at which to start service
If you’ve created an rc script for a service, put your chkconfig line & description line in as listed above. Then you need to add your service to those under the management of chkconfig.
[root@usr-3 init.d]# chkconfig sshd --add
Now you can enable it.
[root@usr-3 init.d]# chkconfig sshd on
You can see by looking at listings of the directories that the appropriate links have been created in each of the run levels.
[root@usr-3 rc.d]# for i in 1 2 3 4 5 6 > do > ls rc$i.d/*ssh* > done rc1.d/K25sshd rc2.d/S55sshd rc3.d/S55sshd rc4.d/S55sshd rc5.d/S55sshd rc6.d/K25sshd
If you didn’t know, the K links pass a stop parameter to the script and the S links send a start parameter. The numbers determine in what order they’ll run relative to the other scripts at a given runlevel. The rc scripts are executed in the order you see when you list them in the directory, first the K’s in numerical order, then the S’s in numerical order. So at run levels 1 and 6 the script is run with a stop parameter, and in run levels 2,3,4,5 it receives a start parameter. We also see this by running a simple command:
[root@usr-3 rc2.d]# chkconfig sshd --list sshd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
Now that you can manage your scripts using chkconfig, here’s a tip that will save you a little bit of typing. When running an rc script to restart a daemon or what have you, the path is pretty long:
[root@usr-3 rc2.d]# /etc/rc.d/init.d/sshd restart
or you could type this instead:
[root@usr-3 rc2.d]# service sshd restart
Hey, it’s 9 keystrokes less! It has some other cool features – get the status on all your services:
[root@usr-3 rc2.d]# service --status-all apmd (pid 682) is running... arpwatch is stopped atd (pid 1151) is running... cannaserver (pid 985) is running... crond (pid 1003) is running... cserver (pid 966) is running... jserver (pid 946) is running... gpm is stopped identd is stopped ipchains: Incompatible with this kernel No status available for this package kserver (pid 1023) is running... lpd is stopped
You get the idea. Have Fun!
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