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Disabling from starting up at boot time

The two common ways for programs to get started at boot time are via
/etc/rc or the System V-type startup scripts. Usually, if you are
running a BSD system it will begin with /etc/rc and most Linux-type
systems use the scripts under /etc/init.d/ (or /etc/rc.d/init.d or
some other similarly named directory). Or your system may start up
programs using both: via /etc/rc and a variety of System V style rc
scripts. (Also, some people may decide to start up programs with init
as configured in /etc/inittab; but we will not discuss this method in
this article.)

For example, on a Linux system, cron might be started via a
/etc/init.d/cron script, Apache started by /etc/init.d/httpd, syslogd by
/etc/init.d/syslogd and sshd started via a /etc/init.d/sshd script.

Basically, these System V scripts are ran via symlinks from a specific rc.d
directory for the current System V runlevel. Linux systems have
different tools for configuring which rc.d scripts are ran. Or you can
configure it manually. There should be one directory that has all the
actual startup scripts (for example, it may be at /etc/init.d/ or
/etc/rc.d/rc.d). Then a few other directories for each runlevel (for
example, they may be named like /etc/rc2.d or /etc/rc.d/rc2.d).
The files in these directories are usually symlinks to the real scripts.
The standard runlevels are usually 2, 3, 4 or 5. You may be able to find
out your default runlevel on a Linux box by searching for “initdefault”
in the /etc/inittab file.

To manually disable a startup script, simply delete the appropriate symlink.
(Ignore the “S” or “K” and the number at the beginning of the symlink
name.) Some tools for managing this include: update-rc.d and chkconfig.
(Plus there are a few GUI equivalents.) For example, you can run
chkconfig --list” to view the current System V style init
script settings.
You can remove the lpd startup links with update-rc.d by doing
/usr/sbin/update-rc.d -f lpd remove“. For futher information,
(if these commands exist on your system) read the manual pages.

It is a lot simpler with just the plain /etc/rc script.
Instead of having a variety of scripts to start numerous different
programs, the programs are simply all just started via one script.
Sometimes /etc/rc may call an additional script, /etc/rc.local, which may
start other tasks. (And some systems that use /etc/rc may also use the
/etc/rc.d/, System V-style scripts.)
To disable a daemon at startup,
simply comment out the lines that start it up in the /etc/rc script.

Some BSD systems may have a configuration file, like /etc/rc.conf which
can be used instead of editing the /etc/rc file. For example, if it says
“inetd=YES” and you want to disable it from starting when the system
boots up, then simply change it to “inetd=NO”.

Uninstalling unneeded software

You may also find your system easier to manage if you actually remove
the unneeded or unused software. If your system is installed using
software packages (i.e. BSD ports/packages collection, RPMs or Debian
dpkg format), it would be a good idea to simply uninstall any unneeded
packages. For example, on systems that use the .deb packaging format,
you can uninstall gpm with “dpkg --remove gpm“.

It is a lot harder to manually remove individual software. For example,
you probably don’t need any X servers or X clients, so you could remove
them, for example, from /usr/X11R6/bin/. Some perfectionists strip their
systems entirely clean removing every tool, configuration or program
that is not needed. I don’t believe you need to go this extreme.

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