Debian info for Sys Admins - RFC.
A group with whom I work is interested in using and supporting Linux.
These people have substantial experience in supporting many flavors of
Unix. Some of them have used RedHat on their own computers but none
have experience with Debian. As I am an enthusiastic Debian user and
I want to spread the word a bit, I offered to do a sample installation
for them this afternoon.
I wrote a few notes on things that you may not otherwise find out in
the documentation. I enclose them below. I welcome comments and
especially corrections if I mis-stated something.
Remember that the audience being addressed is a group of sophisticated
Unix Systems Administrators.
The full name of Debian is Debian GNU Linux reflecting the fact that
Linux is substantially based on the GNU system. The Free Software
Foundation sponsored the initial development of Debian by paying
Ian Murdoch's salary for some time when he first started the project.
The name Debian itself comes from Deborah and Ian Murdoch. Ian
resigned as director of the project several years ago but the name
propagates.
The distribution is currently the property of a non-profit
organization called Software in the Public Interest. The director is
Bruce Perens. He is also the chief architect of Debian. He works for
Pixar as a System Admin. If you see mail from him on a mailing list
or news group it is worth reading. He is very good.
There is always a "stable" and an "unstable" or development
distribution. In the master and mirror ftp sites those names are
symbolic links to actual directories named rex, bo, hamm,
... (characters from the movie "Toy Story"). Right now bo
(a.k.a. Debian-1.3.1) is the stable distribution. It is ELF-based but
uses the Linux libc5 (based on GNU libc 1) libraries. These are not
thread-safe. The unstable directory is hamm, the development version
of Debian-2.0. It is based on libc6 (GNU libc 2) which is (should
be?) thread-safe.
A goal is to provide parallel releases for Intel x86, Alpha, Sparc,
PPC and any other architectures on which Linux runs. Understandably
the most complete release is that for Intel x86. Within the
directories for distributions you will see subdirectories for source
and for binary-alpha, binary-i386, binary-sparc, etc. There is
usually a symbolic link "binary" to binary-i386.
In addition to "stable" and "unstable" you will see directories for
"contrib" and "non-free". Packages in these directories are not
covered by the equivalent of the GPL or the Artistic License. They
can be installed for personal use but should not be redistributed by
CD-ROM manufacturers unless the manufacturer obtains separate
permission. Debian encourages people or companies to create and sell
CD-ROMS's from their distribution. There is no royalty required.
There are tools for creating CD-ROM images. This may be handy if you
eventually decided to create a CD-ROM for your own installation.
Be aware that even the "stable" distribution changes frequently.
Because Debian is a distributed development effort there has been
considerable effort in creating the package management tools. The
basic tool is called "dpkg". It installs, uninstalls, verifies,
... packages in Debian's .deb format. That format contains a gzip'd
tar archive of all files to be installed for the package and another
gzip'd tar archive of the control information. The control
information lists package dependencies and also contains any scripts
that should be run before or after installation or removal. These
scripts eventually end up in the /var/lib/dpkg/info/ directory. For
example:
/var/lib/dpkg/info:
total 3500
drwxr-xr-x 3 root root 33792 Aug 13 08:58 .
drwxr-xr-x 6 root root 1024 Aug 13 08:58 ..
-rw-r--r-- 1 root root 61 Jul 9 21:29 acct.conffiles
-rw-r--r-- 1 root root 540 Jul 11 17:10 acct.list
-rwxr-xr-x 1 root root 1026 Jul 9 21:29 acct.postinst
-rwxr-xr-x 1 root root 615 Jul 9 21:29 acct.postrm
-rwxr-xr-x 1 root root 365 Jul 9 21:29 acct.preinst
-rwxr-xr-x 1 root root 576 Jul 9 21:29 acct.prerm
...
-rw-r--r-- 1 root root 667 May 19 10:22 mysql-manual.list
-rw-r--r-- 1 root root 1096 Apr 12 14:43 mysql-manual.md5sums
-rw-r--r-- 1 root root 17 May 11 08:35 mysql.conffiles
-rw-r--r-- 1 root root 1965 Jul 31 13:46 mysql.list
-rw-r--r-- 1 root root 3235 May 11 08:35 mysql.md5sums
-rwxr-xr-x 1 root root 269 May 11 08:35 mysql.postinst
-rwxr-xr-x 1 root root 386 May 11 08:35 mysql.postrm
-rwxr-xr-x 1 root root 194 May 11 08:35 mysql.prerm
-rw-r--r-- 1 root root 23 May 11 08:35 mysql.shlibs
...
The dpkg program is the raw interface to package management. It is
fine for installing one or two packages or quick maintenance chores.
For larger scale work where dependencies can get messy the full-screen
tool "dselect" is used. It is really a bear to get used to. Once you
do get used to using it, it is very convenient. I update the software
on my system at least every week.
*Very important* - the first time you use dselect after an
installation from scratch, just take the default settings that it
gives you and install them. Don't do any selection at this point or
you will get hopelessly muddled. That is, when you get to the select
option from the initial screen, you will get a screen with packages
already selected. *Just hit return* and take the recommended
selections, then go to install. Later you can come back and do the
actual package selection. You have been warned!
The primary distribution site is ftp://ftp.debian.org/. I use a very
fast mirror from Brookhaven National Lab called
ftp://llug.sep.bnl.gov/pub/debian/
As described in file README.non-US at the top level of the
distribution site, any packages that cannot legally be exported from
the U.S. are kept at offshore sites. These packages include pgp and
ssh. For me the best mirror is Jim Pick's site in Canada
ftp://jimpick.com/pub/mirrors/debian-non-US/
An rpm package is available for Debian to install or uninstall RedHat
.rpm files. Especially commercial software tends to be packaged as
.rpm before being packaged as a .deb file. The recommended way of
using .rpm files is to install both the "alien" and the "rpm" packages
and use alien to install the .rpm file as a virtual Debian package.
There is a development underway to produce a new package tool called Deity.
--
Douglas Bates bates@stat.wisc.edu
Statistics Department 608/262-2598
University of Wisconsin - Madison http://www.stat.wisc.edu/~bates/
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