Gentoo:rc-update

From Linux 101, The beginner's guide to all things Linux.

[edit] What is rc-update?

rc-update is a root only script which allows for the addition, removal, and listing of startup scripts on your Gentoo Linux system.

[edit] How is rc-update useful?

rc-update is one of the main ways Gentoo deals with starting programs on boot. It has, by default although more may be added by the user, three runlevels: default, boot, and nonetwork. For instance, if you wished to start your login manager you would use rc-update to add the login manager's script to the default runlevel.

[edit] How does rc-update work?

rc-update has three parameters associated with it: add (-a), del (-d), and show (-s). In order to add something to a certain runlevel, such as the above example of a login manager (in this case gdm) the following command would be issued:

# rc-update add gdm default

The first parameter of "add" tells rc-update that you wish to put a program into the runlevel, "gdm" tells rc-update which script will be added, and "default" is the runlevel you are adding to. If you accidentally add something to start when you didn't mean to, or you simply don't want it to start on boot any longer, simply switch the "add" out for "del" like so:

# rc-update del gdm default

This will remove gdm from the default runlevel and stop it from loading on startup.

Note: If you do not specify a runlevel, rc-update will remove the selected script from all runlevels it finds it in.

The final parameter, show, will show which scripts are available for use with rc-update (you may also simply look in /etc/init.d/) and also what runlevel(s) they are currently set to, if any.

# rc-update show

            apache2 |      default
           bootmisc | boot
            checkfs | boot
          checkroot | boot
              clock | boot
        consolefont | boot
           hostname | boot
            keymaps | boot
              local |      default nonetwork
         localmount | boot
            metalog |      default
            modules | boot
              mysql |      default
           net.eth0 |      default
             net.lo | boot
           netmount |      default
          rmnologin | boot
              samba |      default
             serial | boot
               sshd |      default
            urandom | boot
         vixie-cron |      default

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