<linkhref="ch-software.en.html"rel="chapter"title="5 Software available in the Debian system">
<linkhref="ch-ftparchives.en.html"rel="chapter"title="6 The Debian FTP archives">
<linkhref="ch-pkg_basics.en.html"rel="chapter"title="7 Basics of the Debian package management system">
<linkhref="ch-pkgtools.en.html"rel="chapter"title="8 The Debian package management tools">
<linkhref="ch-uptodate.en.html"rel="chapter"title="9 Keeping your Debian system up-to-date">
<linkhref="ch-kernel.en.html"rel="chapter"title="10 Debian and the kernel">
<linkhref="ch-customizing.en.html"rel="chapter"title="11 Customizing your installation of Debian GNU/Linux">
<linkhref="ch-support.en.html"rel="chapter"title="12 Getting support for Debian GNU/Linux">
<linkhref="ch-contributing.en.html"rel="chapter"title="13 Contributing to the Debian Project">
<linkhref="ch-redistrib.en.html"rel="chapter"title="14 Redistributing Debian GNU/Linux in a commercial product">
<linkhref="ch-nexttime.en.html"rel="chapter"title="15 Changes expected in the next major release of Debian">
<linkhref="ch-faqinfo.en.html"rel="chapter"title="16 General information about the FAQ">
<linkhref="ch-basic_defs.en.html#s-whatisfaq"rel="section"title="1.1 What is this FAQ?">
<linkhref="ch-basic_defs.en.html#s-whatisdebian"rel="section"title="1.2 What is Debian GNU/Linux?">
<linkhref="ch-basic_defs.en.html#s-linux"rel="section"title="1.3 OK, now I know what Debian is... what is Linux?!">
<linkhref="ch-basic_defs.en.html#s-non-linux"rel="section"title="1.4 Does Debian just do GNU/Linux?">
<linkhref="ch-basic_defs.en.html#s-difference"rel="section"title="1.5 What is the difference between Debian GNU/Linux and other Linux distributions? Why should I choose Debian over some other distribution?">
<linkhref="ch-basic_defs.en.html#s-gnu"rel="section"title="1.6 How does the Debian project fit in or compare with the Free Software Foundation's GNU project?">
<linkhref="ch-basic_defs.en.html#s-pronunciation"rel="section"title="1.7 How does one pronounce Debian and what does this word mean?">
<linkhref="ch-getting.en.html#s-version"rel="section"title="2.1 What is the latest version of Debian?">
<linkhref="ch-getting.en.html#s-updatestable"rel="section"title="2.2 Are there package upgrades in `stable'?">
<linkhref="ch-getting.en.html#s-boot-floppies"rel="section"title="2.3 Where/how can I get the Debian installation disks?">
<linkhref="ch-getting.en.html#s-cdrom"rel="section"title="2.4 How do I install the Debian from CD-ROMs?">
<linkhref="ch-getting.en.html#s-cdimage-symlinks"rel="section"title="2.5 Why does the official stable released CD-ROM contain symlinks for `frozen' and `unstable'? I thought this CD contains just `stable'!">
<linkhref="ch-getting.en.html#s-remoteinstall"rel="section"title="2.6 Can I get and install Debian directly from a remote Internet site?">
<linkhref="ch-getting.en.html#s-alternativebootinstaller"rel="section"title="2.7 Are there any alternative strategies for booting the system installer?">
<linkhref="ch-choosing.en.html#s3.1"rel="section"title="3.1 Which Debian distribution (stable/testing/unstable) is better for me?">
<linkhref="ch-choosing.en.html#s3.2"rel="section"title="3.2 But what about Knoppix, Linex, Ubuntu, and others?">
<linkhref="ch-compat.en.html#s-arches"rel="section"title="4.1 On what hardware architectures/systems does Debian GNU/Linux run?">
<linkhref="ch-compat.en.html#s-otherdistribs"rel="section"title="4.2 How compatible is Debian with other distributions of Linux?">
<linkhref="ch-compat.en.html#s-otherunices"rel="section"title="4.3 How source code compatible is Debian with other Unix systems?">
<linkhref="ch-compat.en.html#s-otherpackages"rel="section"title="4.4 Can I use Debian packages (".deb" files) on my Red Hat/Slackware/... Linux system? Can I use Red Hat packages (".rpm" files) on my Debian GNU/Linux system?">
<linkhref="ch-compat.en.html#s-non-debian-programs"rel="section"title="4.5 How should I install a non-Debian program?">
<linkhref="ch-compat.en.html#s-termcap"rel="section"title="4.6 Why can't I compile programs that require libtermcap?">
<linkhref="ch-compat.en.html#s-accelx"rel="section"title="4.7 Why can't I install AccelX?">
<linkhref="ch-compat.en.html#s-motifnls"rel="section"title="4.8 Why do my old XFree 2.1 Motif applications crash?">
<linkhref="ch-software.en.html#s-apps"rel="section"title="5.1 What types of applications and development software are available for Debian GNU/Linux?">
<linkhref="ch-software.en.html#s-softwareauthors"rel="section"title="5.2 Who wrote all that software?">
<linkhref="ch-software.en.html#s-pkglist"rel="section"title="5.3 How can I get a current list of programs that have been packaged for Debian?">
<linkhref="ch-software.en.html#s-buildenv"rel="section"title="5.4 How can I install a developer's environment to build packages?">
<linkhref="ch-software.en.html#s-missing"rel="section"title="5.5 What is missing from Debian GNU/Linux?">
<linkhref="ch-software.en.html#s-no-devs"rel="section"title="5.6 Why do I get "ld: cannot find -lfoo" messages when compiling programs? Why aren't there any libfoo.so files in Debian library packages?">
<linkhref="ch-software.en.html#s-java"rel="section"title="5.7 (How) Does Debian support Java?">
<linkhref="ch-software.en.html#s-isitdebian"rel="section"title="5.8 How can I check that I am using a Debian system, and what version is it?">
<linkhref="ch-software.en.html#s-nonenglish"rel="section"title="5.9 How does Debian support non-English languages?">
<linkhref="ch-software.en.html#s-pine"rel="section"title="5.10 Where is pine?">
<linkhref="ch-software.en.html#s-qmail"rel="section"title="5.11 Where is qmail/ezmlm/djbdns?">
<linkhref="ch-software.en.html#s-flash"rel="section"title="5.12 Where is a player for Flash (SWF)?">
<linkhref="ch-software.en.html#s-googleearth"rel="section"title="5.13 Where is Google Earth?">
<linkhref="ch-software.en.html#s-voip"rel="section"title="5.14 Where is VoIP software?">
<linkhref="ch-software.en.html#s-nonfreewireless"rel="section"title="5.15 I have a wireless network card which doesn't work with Linux. What should I do?">
<linkhref="ch-ftparchives.en.html#s-dists"rel="section"title="6.1 How many Debian distributions are there?">
<linkhref="ch-ftparchives.en.html#s-codenames"rel="section"title="6.2 What are all those names like etch, lenny, etc.?">
<linkhref="ch-ftparchives.en.html#s-sid"rel="section"title="6.3 What about "sid"?">
<linkhref="ch-ftparchives.en.html#s-stable"rel="section"title="6.4 What does the stable directory contain?">
<linkhref="ch-ftparchives.en.html#s-testing"rel="section"title="6.5 What does the testing distribution contain?">
<linkhref="ch-ftparchives.en.html#s-unstable"rel="section"title="6.6 What does the unstable distribution contain?">
<linkhref="ch-ftparchives.en.html#s-dirtree"rel="section"title="6.7 What are all those directories at the Debian FTP archives?">
<linkhref="ch-ftparchives.en.html#s-archsections"rel="section"title="6.8 What are all those directories inside <samp>dists/stable/main</samp>?">
<linkhref="ch-ftparchives.en.html#s-source"rel="section"title="6.9 Where is the source code?">
<linkhref="ch-ftparchives.en.html#s-pools"rel="section"title="6.10 What's in the <samp>pool</samp> directory?">
<linkhref="ch-ftparchives.en.html#s-incoming"rel="section"title="6.11 What is "incoming"?">
<linkhref="ch-ftparchives.en.html#s-ownrepository"rel="section"title="6.12 How do I set up my own apt-able repository?">
<linkhref="ch-pkg_basics.en.html#s-package"rel="section"title="7.1 What is a Debian package?">
<linkhref="ch-pkg_basics.en.html#s-deb-format"rel="section"title="7.2 What is the format of a Debian binary package?">
<linkhref="ch-pkg_basics.en.html#s-pkgname"rel="section"title="7.3 Why are Debian package file names so long?">
<linkhref="ch-pkg_basics.en.html#s-controlfile"rel="section"title="7.4 What is a Debian control file?">
<linkhref="ch-pkg_basics.en.html#s-conffile"rel="section"title="7.5 What is a Debian conffile?">
<linkhref="ch-pkg_basics.en.html#s-maintscripts"rel="section"title="7.6 What is a Debian preinst, postinst, prerm, and postrm script?">
<linkhref="ch-pkg_basics.en.html#s-priority"rel="section"title="7.7 What is an <em>Essential</em>, <em>Required</em>, <em>Important</em>, <em>Standard</em>, <em>Optional</em>, or <em>Extra</em> package?">
<linkhref="ch-pkg_basics.en.html#s-virtual"rel="section"title="7.8 What is a Virtual Package?">
<linkhref="ch-pkg_basics.en.html#s-depends"rel="section"title="7.9 What is meant by saying that a package <em>Depends</em>, <em>Recommends</em>, <em>Suggests</em>, <em>Conflicts</em>, <em>Replaces</em> or <em>Provides</em> another package?">
<linkhref="ch-pkg_basics.en.html#s-pre-depends"rel="section"title="7.10 What is meant by Pre-Depends?">
<linkhref="ch-pkg_basics.en.html#s-pkgstatus"rel="section"title="7.11 What is meant by <em>unknown</em>, <em>install</em>, <em>remove</em>, <em>purge</em> and <em>hold</em> in the package status?">
<linkhref="ch-pkg_basics.en.html#s-puttingonhold"rel="section"title="7.12 How do I put a package on hold?">
<linkhref="ch-pkg_basics.en.html#s-sourcepkgs"rel="section"title="7.13 How do I install a source package?">
<linkhref="ch-pkg_basics.en.html#s-sourcebuild"rel="section"title="7.14 How do I build binary packages from a source package?">
<linkhref="ch-pkg_basics.en.html#s-creatingdebs"rel="section"title="7.15 How do I create Debian packages myself?">
<linkhref="ch-pkgtools.en.html#s-pkgprogs"rel="section"title="8.1 What programs does Debian provide for managing its packages?">
<linkhref="ch-pkgtools.en.html#s-updaterunning"rel="section"title="8.2 Debian claims to be able to update a running program; how is this accomplished?">
<linkhref="ch-pkgtools.en.html#s-whatpackages"rel="section"title="8.3 How can I tell what packages are already installed on a Debian system?">
<linkhref="ch-pkgtools.en.html#s-listfiles"rel="section"title="8.4 How to display the files of a package installed?">
<linkhref="ch-pkgtools.en.html#s-filesearch"rel="section"title="8.5 How can I find out what package produced a particular file?">
<linkhref="ch-pkgtools.en.html#s-datapackages"rel="section"title="8.6 Why doesn't get `foo-data' removed when I uninstall `foo'? How do I make sure old unused library-packages get purged?">
<linkhref="ch-uptodate.en.html#s-howtocurrent"rel="section"title="9.1 How can I keep my Debian system current?">
<linkhref="ch-uptodate.en.html#s-upgradesingle"rel="section"title="9.2 Must I go into single user mode in order to upgrade a package?">
<linkhref="ch-uptodate.en.html#s-savedebs"rel="section"title="9.3 Do I have to keep all those .deb archive files on my disk?">
<linkhref="ch-uptodate.en.html#s-keepingalog"rel="section"title="9.4 How can I keep a log of the packages I added to the system? I'd like to know when which package upgrades and removals have occured!">
<linkhref="ch-uptodate.en.html#s-autoupdate"rel="section"title="9.5 Can I automatically update the system?">
<linkhref="ch-uptodate.en.html#s-aptproxy"rel="section"title="9.6 I have several machines how can I download the updates only one time?">
<linkhref="ch-kernel.en.html#s-non-debian-kernel"rel="section"title="10.1 Can I install and compile a kernel without some Debian-specific tweaking?">
<linkhref="ch-kernel.en.html#s-customkernel"rel="section"title="10.2 What tools does Debian provide to build custom kernels?">
<linkhref="ch-kernel.en.html#s-custombootdisk"rel="section"title="10.3 How can I make a custom boot floppy?">
<linkhref="ch-kernel.en.html#s-modules"rel="section"title="10.4 What special provisions does Debian provide to deal with modules?">
<linkhref="ch-kernel.en.html#s-removeoldkernel"rel="section"title="10.5 Can I safely de-install an old kernel package, and if so, how?">
<linkhref="ch-customizing.en.html#s-papersize"rel="section"title="11.1 How can I ensure that all programs use the same paper size?">
<linkhref="ch-customizing.en.html#s-hardwareaccess"rel="section"title="11.2 How can I provide access to hardware peripherals, without compromising security?">
<linkhref="ch-customizing.en.html#s-consolefont"rel="section"title="11.3 How do I load a console font on startup the Debian way?">
<linkhref="ch-customizing.en.html#s-appdefaults"rel="section"title="11.4 How can I configure an X11 program's application defaults?">
<linkhref="ch-customizing.en.html#s-booting"rel="section"title="11.5 Every distribution seems to have a different boot-up method. Tell me about Debian's.">
<linkhref="ch-customizing.en.html#s-custombootscripts"rel="section"title="11.6 It looks as if Debian does not use <samp>rc.local</samp> to customize the boot process; what facilities are provided?">
<linkhref="ch-customizing.en.html#s-interconffiles"rel="section"title="11.7 How does the package management system deal with packages that contain configuration files for other packages?">
<linkhref="ch-customizing.en.html#s-divert"rel="section"title="11.8 How do I override a file installed by a package, so that a different version can be used instead?">
<linkhref="ch-customizing.en.html#s-localpackages"rel="section"title="11.9 How can I have my locally-built package included in the list of available packages that the package management system knows about?">
<linkhref="ch-customizing.en.html#s-diverse"rel="section"title="11.10 Some users like mawk, others like gawk; some like vim, others like elvis; some like trn, others like tin; how does Debian support diversity?">
<linkhref="ch-support.en.html#s-debiandocs"rel="section"title="12.1 What other documentation exists on and for a Debian system?">
<linkhref="ch-support.en.html#s-onlineresources"rel="section"title="12.2 Are there any on-line resources for discussing Debian?">
<linkhref="ch-support.en.html#s-searchtools"rel="section"title="12.3 Is there a quick way to search for information on Debian GNU/Linux?">
<linkhref="ch-support.en.html#s-buglogs"rel="section"title="12.4 Are there logs of known bugs?">
<linkhref="ch-support.en.html#s-bugreport"rel="section"title="12.5 How do I report a bug in Debian?">
<linkhref="ch-contributing.en.html#s-contrib"rel="section"title="13.1 How can I become a Debian software developer?">
<linkhref="ch-contributing.en.html#s-contribresources"rel="section"title="13.2 How can I contribute resources to the Debian project?">
<linkhref="ch-contributing.en.html#s-supportingorganizations"rel="section"title="13.3 How can I contribute financially to the Debian project?">
<linkhref="ch-redistrib.en.html#s-sellcds"rel="section"title="14.1 Can I make and sell Debian CDs?">
<linkhref="ch-redistrib.en.html#s-packagednonfree"rel="section"title="14.2 Can Debian be packaged with non-free software?">
<linkhref="ch-redistrib.en.html#s-childistro"rel="section"title="14.3 I am making a special Linux distribution for a "vertical market". Can I use Debian GNU/Linux for the guts of a Linux system and add my own applications on top of it?">
<linkhref="ch-redistrib.en.html#s-commercialdebs"rel="section"title="14.4 Can I put my commercial program in a Debian "package" so that it installs effortlessly on any Debian system?">
<linkhref="ch-nexttime.en.html#s-i18n"rel="section"title="15.1 Extended support for non-English users">
<linkhref="ch-nexttime.en.html#s-dependencybasedboot"rel="section"title="15.2 Faster booting: Dependency based boot sequence">
<linkhref="ch-nexttime.en.html#s-di"rel="section"title="15.3 Improvements in the Debian Installer">
<linkhref="ch-nexttime.en.html#s-morearches"rel="section"title="15.4 More architectures">
<linkhref="ch-nexttime.en.html#s-morekernels"rel="section"title="15.5 More kernels">
<linkhref="ch-choosing.en.html#s3.1.1"rel="subsection"title="3.1.1 You asked me to install stable, but in stable so and so hardware is not detected/working. What should I do?">
<linkhref="ch-choosing.en.html#s3.1.2"rel="subsection"title="3.1.2 Will there be different different versions of packages in different distributions?">
<linkhref="ch-choosing.en.html#s3.1.3"rel="subsection"title="3.1.3 The stable distributions really contains outdated packages. Just look at Kde, Gnome, Xorg or even the kernel. They are very old. Why is it so?">
<linkhref="ch-choosing.en.html#s3.1.4"rel="subsection"title="3.1.4 If I were to decide to change to another distribution, Can I do that?">
<linkhref="ch-choosing.en.html#s3.1.5"rel="subsection"title="3.1.5 Could you tell me whether to install testing or unstable?">
<linkhref="ch-choosing.en.html#s3.1.6"rel="subsection"title="3.1.6 You are talking about testing being broken. What do you mean by that?">
<linkhref="ch-choosing.en.html#s3.1.7"rel="subsection"title="3.1.7 Why is it that testing could be broken for months? Wont the fixes introduced in unstable flow directly down into testing?">
<linkhref="ch-choosing.en.html#s3.1.8"rel="subsection"title="3.1.8 From an administrator's point of view, Which distribution requires more attention?">
<linkhref="ch-choosing.en.html#s3.1.9"rel="subsection"title="3.1.9 What happens when a new release is made?">
<linkhref="ch-choosing.en.html#s3.1.10"rel="subsection"title="3.1.10 I have a working Desktop/cluster with Debian installed. How do I know which distribution I am running?">
<linkhref="ch-choosing.en.html#s3.1.11"rel="subsection"title="3.1.11 I am currently tracking stable. Can I change to testing or unstable? If so, How?">
<linkhref="ch-choosing.en.html#s3.1.12"rel="subsection"title="3.1.12 I am currently tracking testing (lenny). What will happen when a release is made? Will I still be tracking testing or will my machine be running the new stable distribution?">
<linkhref="ch-choosing.en.html#s3.1.13"rel="subsection"title="3.1.13 I am still confused. What did you say I should install?">
<linkhref="ch-choosing.en.html#s3.2.1"rel="subsection"title="3.2.1 I know that Knoppix/Linex/Ubuntu/... is Debian-based. So after installing it on the hard disk, can I use 'apt' package tools on it?">
<linkhref="ch-choosing.en.html#s3.2.2"rel="subsection"title="3.2.2 I installed Knoppix/Linex/Ubuntu/... on my hard disk. Now I have a problem. What should I do?">
<linkhref="ch-choosing.en.html#s3.2.3"rel="subsection"title="3.2.3 I'm using Knoppix/Linex/Ubuntu/... and now I want to use Debian. How do I migrate?">
<linkhref="ch-ftparchives.en.html#s-oldcodenames"rel="subsection"title="6.2.1 Which other codenames have been used in the past?">
<linkhref="ch-ftparchives.en.html#s-sourceforcodenames"rel="subsection"title="6.2.2 Where do these codenames come from?">
<linkhref="ch-ftparchives.en.html#s-frozen"rel="subsection"title="6.5.1 What about "testing"? How is it `frozen'?">
<br>Chapter 11 - Customizing your installation of Debian GNU/Linux
</h1>
<hr>
<h2><aname="s-papersize"></a>11.1 How can I ensure that all programs use the same paper size?</h2>
<p>
Install the <code>libpaper1</code> package, and it will ask you for a
system-wide default paper size. This setting will be kept in the file
<samp>/etc/papersize</samp>.
</p>
<p>
Users can override the paper size setting using the <samp>PAPERSIZE</samp>
environment variable. For details, see the manual page
<code>papersize(5)</code>.
</p>
<hr>
<h2><aname="s-hardwareaccess"></a>11.2 How can I provide access to hardware peripherals, without compromising security?</h2>
<p>
Many device files in the <samp>/dev</samp> directory belong to some predefined
groups. For example, <samp>/dev/fd0</samp> belongs to the <samp>floppy</samp>
group, and <samp>/dev/dsp</samp> belongs to the <samp>audio</samp> group.
</p>
<p>
If you want a certain user to have access to one of these devices, just add the
user to the group the device belongs to, i.e. do:
</p>
<pre>
adduser user group
</pre>
<p>
This way you won't have to change the file permissions on the device.
</p>
<p>
If you do this from within a user's shell or a GUI environment you have to
logout and login again to become an effective member of that group. To check
which groups you belong to run <samp>groups</samp>.
</p>
<p>
Notice that, since the introduction of <samp>udev</samp> if you change the
permissions of a hardware peripheral they might be be adjusted for some devices
when the system starts, if this happens to the hardware peripherals you are
instered in you will have to adjust the rules at <samp>/etc/udev</samp>.
</p>
<hr>
<h2><aname="s-consolefont"></a>11.3 How do I load a console font on startup the Debian way?</h2>
<p>
The <code>kbd</code> and <code>console-tools</code> packages support this, edit
<samp>/etc/kbd/config</samp> or <samp>/etc/console-tools/config</samp> files.
</p>
<hr>
<h2><aname="s-appdefaults"></a>11.4 How can I configure an X11 program's application defaults?</h2>
<p>
Debian's X programs will install their application resource data in the
<samp>/etc/X11/app-defaults/</samp> directory. If you want to customize X
applications globally, put your customizations in those files. They are marked
as configuration files, so their contents will be preserved during upgrades.
</p>
<hr>
<h2><aname="s-booting"></a>11.5 Every distribution seems to have a different boot-up method. Tell me about Debian's.</h2>
<p>
Like all Unices, Debian boots up by executing the program <samp>init</samp>.
The configuration file for <samp>init</samp> (which is
<samp>/etc/inittab</samp>) specifies that the first script to be executed
should be <samp>/etc/init.d/rcS</samp>. This script runs all of the scripts in
<samp>/etc/rcS.d/</samp> by sourcing or forking subprocess depending on their
file extension to perform initialization such as to check and to mount file
systems, to load modules, to start the network services, to set the clock, and
to perform other initialization. Then, for compatibility, it runs the files
(except those with a `.'in the filename) in <samp>/etc/rc.boot/</samp> too.
Any scripts in the latter directory are usually reserved for system
administrator use, and using them in packages is deprecated.
</p>
<p>
After completing the boot process, <samp>init</samp> executes all start scripts
in a directory specified by the default runlevel (this runlevel is given by the
entry for <samp>id</samp> in <samp>/etc/inittab</samp>). Like most System V
compatible Unices, Linux has 7 runlevels:
</p>
<ul>
<li>
<p>
0 (halt the system),
</p>
</li>
</ul>
<ul>
<li>
<p>
1 (single-user mode),
</p>
</li>
</ul>
<ul>
<li>
<p>
2 through 5 (various multi-user modes), and
</p>
</li>
</ul>
<ul>
<li>
<p>
6 (reboot the system).
</p>
</li>
</ul>
<p>
Debian systems come with id=2, which indicates that the default runlevel will
be '2' when the multi-user state is entered, and the scripts in
<samp>/etc/rc2.d/</samp> will be run.
</p>
<p>
In fact, the scripts in any of the directories, <samp>/etc/rcN.d/</samp> are
just symbolic links back to scripts in <samp>/etc/init.d/</samp>. However, the
<em>names</em> of the files in each of the <samp>/etc/rcN.d/</samp> directories
are selected to indicate the <em>way</em> the scripts in
<samp>/etc/init.d/</samp> will be run. Specifically, before entering any
runlevel, all the scripts beginning with 'K' are run; these scripts kill
services. Then all the scripts beginning with 'S' are run; these scripts start
services. The two-digit number following the 'K' or 'S' indicates the order in
which the script is run. Lower numbered scripts are executed first.
</p>
<p>
This approach works because the scripts in <samp>/etc/init.d/</samp> all take
an argument which can be either `start', `stop', `reload', `restart' or
`force-reload' and will then do the task indicated by the argument. These
scripts can be used even after a system has been booted, to control various
processes.
</p>
<p>
For example, with the argument `reload' the command
</p>
<pre>
/etc/init.d/sendmail reload
</pre>
<p>
sends the sendmail daemon a signal to reread its configuration file. (BTW,
Debian supplies <code>invoke-rc.d</code> as a wrapper for invoking the scripts
in <samp>/etc/init.d/</samp>.)
</p>
<hr>
<h2><aname="s-custombootscripts"></a>11.6 It looks as if Debian does not use <samp>rc.local</samp> to customize the boot process; what facilities are provided?</h2>
<p>
Suppose a system needs to execute script <samp>foo</samp> on start-up, or on
entry to a particular (System V) runlevel. Then the system administrator
should:
</p>
<ul>
<li>
<p>
Enter the script <samp>foo</samp> into the directory <samp>/etc/init.d/</samp>.
</p>
</li>
</ul>
<ul>
<li>
<p>
Run the Debian command <samp>update-rc.d</samp> with appropriate arguments, to
specify which runlevels should start the service, and which runlevels should
stop the service.
</p>
</li>
</ul>
<ul>
<li>
<p>
Consider rebooting the system to check that the service starts correctly
(assuming that you've asked for it to be started in the default runlevel).
Otherwise, manually start it by running `<samp>/etc/init.d/foo start</samp>'.
</p>
</li>
</ul>
<p>
One might, for example, cause the script <samp>foo</samp> to execute at
boot-up, by putting it in <samp>/etc/init.d/</samp> and running
<samp>update-rc.d foo defaults 19</samp>. The argument `<samp>defaults</samp>'
refers to the default runlevels, which means (at least in absence of any LSB
comment block to the contrary) to start the service in runlevels 2 through 5,
and to stop the service in runlevels 0, 1 and 6. (Any LSB Default-Start and
Default-Stop directives in <samp>foo</samp> take precedence when using the
sysv-rc version of update-rc.d, but are ignored by the current (v0.8.10)
file-rc version of update-rc.d.) The argument `<samp>19</samp>' ensures that
<samp>foo</samp> is called after all scripts whose number is less than 19 have
completed, and before all scripts whose number is 20 or greater.
</p>
<hr>
<h2><aname="s-interconffiles"></a>11.7 How does the package management system deal with packages that contain configuration files for other packages?</h2>
<p>
Some users wish to create, for example, a new server by installing a group of
Debian packages and a locally generated package consisting of configuration
files. This is not generally a good idea, because <code>dpkg</code> will not
know about those configuration files if they are in a different package, and
may write conflicting configurations when one of the initial "group"
of packages is upgraded.
</p>
<p>
Instead, create a local package that modifies the configuration files of the
"group" of Debian packages of interest. Then <code>dpkg</code> and
the rest of the package management system will see that the files have been
modified by the local "sysadmin" and will not try to overwrite them
when those packages are upgraded.
</p>
<hr>
<h2><aname="s-divert"></a>11.8 How do I override a file installed by a package, so that a different version can be used instead?</h2>
<p>
Suppose a sysadmin or local user wishes to use a program
"login-local" rather than the program "login" provided by
the Debian <code>login</code> package.
</p>
<p>
Do <strong>not</strong>:
</p>
<ul>
<li>
<p>
Overwrite <samp>/bin/login</samp> with <samp>login-local</samp>.
</p>
</li>
</ul>
<p>
The package management system will not know about this change, and will simply
overwrite your custom <samp>/bin/login</samp> whenever <samp>login</samp> (or
any package that provides <samp>/bin/login</samp>) is installed or updated.
</p>
<p>
Rather, do
</p>
<ul>
<li>
<p>
Execute:
</p>
<pre>
dpkg-divert --divert /bin/login.debian /bin/login
</pre>
<p>
in order to cause all future installations of the Debian <code>login</code>
package to write the file <samp>/bin/login</samp> to
<samp>/bin/login.debian</samp> instead.
</p>
</li>
</ul>
<ul>
<li>
<p>
Then execute:
</p>
<pre>
cp login-local /bin/login
</pre>
<p>
to move your own locally-built program into place.
</p>
</li>
</ul>
<p>
Run <samp>dpkg-divert --list</samp> to see which diversions are currently
active on your system.
</p>
<p>
Details are given in the manual page <code>dpkg-divert(8)</code>.
</p>
<hr>
<h2><aname="s-localpackages"></a>11.9 How can I have my locally-built package included in the list of available packages that the package management system knows about?</h2>
BIN-DIR is a directory where Debian archive files (which usually have an
extension of ".deb") are stored.
</p>
</li>
</ul>
<ul>
<li>
<p>
OVERRIDE_FILE is a file that is edited by the distribution maintainers and is
usually stored on a Debian FTP archive at <samp>indices/override.main.gz</samp>
for the Debian packages in the "main" distribution. You can ignore
this for local packages.
</p>
</li>
</ul>
<ul>
<li>
<p>
PATHPREFIX is an <em>optional</em> string that can be prepended to the
<samp>my_Packages</samp> file being produced.
</p>
</li>
</ul>
<p>
Once you have built the file <samp>my_Packages</samp>, tell the package
management system about it by using the command:
</p>
<pre>
dpkg --merge-avail my_Packages
</pre>
<p>
If you are using APT, you can add the local repository to your
<code>sources.list(5)</code> file, too.
</p>
<hr>
<h2><aname="s-diverse"></a>11.10 Some users like mawk, others like gawk; some like vim, others like elvis; some like trn, others like tin; how does Debian support diversity?</h2>
<p>
There are several cases where two packages provide two different versions of a
program, both of which provide the same core functionality. Users might prefer
one over another out of habit, or because the user interface of one package is
somehow more pleasing than the interface of another. Other users on the same
system might make a different choice.
</p>
<p>
Debian uses a "virtual" package system to allow system administrators
to choose (or let users choose) their favorite tools when there are two or more
that provide the same basic functionality, yet satisfy package dependency
requirements without specifying a particular package.
</p>
<p>
For example, there might exist two different versions of newsreaders on a
system. The news server package might 'recommend' that there exist
<em>some</em> news reader on the system, but the choice of <samp>tin</samp> or
<samp>trn</samp> is left up to the individual user. This is satisfied by
having both the <code>tin</code> and <code>trn</code> packages provide the
virtual package <code>news-reader</code>. <em>Which</em> program is invoked is
determined by a link pointing from a file with the virtual package name
<samp>/etc/alternatives/news-reader</samp> to the selected file, e.g.,
<samp>/usr/bin/trn</samp>.
</p>
<p>
A single link is insufficient to support full use of an alternate program;
normally, manual pages, and possibly other supporting files must be selected as
well. The Perl script <samp>update-alternatives</samp> provides a way of
ensuring that all the files associated with a specified package are selected as
a system default.
</p>
<p>
For example, to check what executables provide `x-window-manager', run:
</p>
<pre>
update-alternatives --display x-window-manager
</pre>
<p>
If you want to change it, run:
</p>
<pre>
update-alternatives --config x-window-manager
</pre>
<p>
And follow the instructions on the screen (basically, press the number next to
the entry you'd like better).
</p>
<p>
If a package doesn't register itself as a window manager for some reason (file
a bug if it's in error), or if you use a window manager from /usr/local
directory, the selections on screen won't contain your preferred entry. You
can update the link through command line options, like this:
