 | Level: Introductory Daniel Robbins (drobbins@gentoo.org), President/CEO, Gentoo Technologies, Inc
01 Sep 2000 So, you've compiled and installed your first application from source code, and it's working great. Congratulations! But now, there's a new version of the sources available and you'd like to upgrade, but you want to make sure that everything goes smoothly. What practical steps can you take to avoid pitfalls? In this tip, I'll show you several.
Upgrading can be simple
Upgrading software from sources can be very simple, but there are
several precautions you should take, especially if you're new
to compiling from sources, or if you're not very familiar with the
particular source archive you are installing. The top things to watch
out for are listed below, but in most cases, an update is almost
identical to the original compilation and install steps. That is,
the steps include a tarball extraction, a possible "./configure", "make", and "make install". If these terms are not familiar to you, then
check out developerWorks' tutorial on Compiling and installing software from sources, and then head back here.
Read the Changelog
After downloading the sources, familiarize yourself with any new
changes to the software -- normally, these changes are itemized in the
ChangeLog or README file in the main source directory. You may find
that configuration file settings have changed slightly, or that new
features have been added. It's best to find out about these changes
from the source documentation, rather than stumbling upon them later. Not doing so is definitely a bad
move -- and besides, since you're taking the time to install a new
version of this particular software package, wouldn't it be a good thing to
know what new features or bug fixes are included?
Upgrading critical applications
If you're upgrading an application that many users rely on (like
the Apache on your busy Web server), then it pays to be extremely careful.
If possible, practice installing the new version of the sources on a
non-production box, and write down all the steps you performed to get
the new version up and running. That way, if you run into a problem
during the upgrade, no harm is done. And, when you're ready to
upgrade your production box, you'll have a careful list of steps
to perform -- reducing precious downtime.
In addition, if you're upgrading a critical app, it's always best to do
so during off-peak hours.
Configure it the same way
One of the main mistakes that people make when upgrading an app is to
specify different and incompatible options on the "./configure" line
or to uncomment different lines in a configuration Makefile. If you want to perform a simple upgrade, make sure
that the new version of the software is configured exactly like your current version was.
If your current version looks for its configuration files in /etc, it would be nice
if the new version did too. Don't be sloppy; if you pass
different options to the "./configure" command, you could easily end
up with a new version that has significantly different functionality,
installs into the wrong directory tree, or looks in the wrong place
for its configuration or data files. If you can't remember the
configure options or Makefile defines you used originally, make sure
you find out before you compile and install the new sources.
To make the upgrade go smoothly, you'll want to get these settings right
from the start.
Back up old config files before install
For many packages, the real challenge comes not in the compilation and
installation stages, but in the process of setting up an application
to work properly after you've typed "make install". This normally involves spending a few good hours
editing an application's config file, which is normally found in /etc,
sporting the popular ".conf" suffix.
When you install a new version of a package by typing "make install",
most Makefiles won't overwrite your existing configuration
files sitting on disk -- but it's always better to be safe than sorry. If you're not
completely sure, by all means back up those precious config files!
Depending on the package, some configuration files could take days to
reconstruct. If they happen to contain encrypted passwords,
reconstruction may be extremely time consuming or impossible.
If you're planning on making major upgrades to your Linux system, this may
be a good time to perform a full system backup. It's
an especially good idea if you're going to upgrade a critical system library or
tool that many other packages depend on to function properly. Full system backups are good
things in their own right, and I hope you back up your system on at least a
semi-regular basis.
Keep the older source handy
I don't mean to discourage you from upgrading to the latest version of
your favorite program -- but it is possible that the new
version simply won't work. Maybe "./configure" will bomb out, or
maybe "make" will. Worst case scenario, maybe everything, including "make
install", will go splendidly until you actually try to run the
program. Buggy source releases do happen, and that's why it's a great
idea to keep your older sources (and any installation steps) handy in
case the newer sources aren't up to snuff.
Test it!
It's one thing to compile and install something, and quite another
thing to make sure that the new software actually works. You'll want
to make sure that you didn't just install 500 KB worth of garbage onto
your root partition. Maybe the new version's config file needs slight, or even heavy, tweaking.
If you're
updating a daemon, make sure your configuration scripts
successfully start the new version on reboot. You definitely don't
want to find any problems two weeks later, when you reboot your
server (and the program's configuration details are not fresh in
your mind). You can follow all the advice in this article,
but if you don't test your setup, you're skipping the most important step.
Now, you should be adequately equipped to upgrade your
favorite app. Have fun!
Resources
About the author | | | Residing in Albuquerque, New Mexico, Daniel Robbins is the
President/CEO of Gentoo Technologies,
Inc., the creator of Gentoo Linux, an advanced Linux for the
PC, and the Portage system, a next-generation ports system for Linux.
He has also served as a contributing author for the Macmillan books
Caldera OpenLinux Unleashed, SuSE Linux Unleashed, and Samba Unleashed.
Daniel has been involved with computers in some fashion since the
second grade, when he was first exposed to the Logo programming
language as well as a potentially dangerous dose of Pac Man. This
probably explains why he has since served as a Lead Graphic Artist at
SONY Electronic Publishing/Psygnosis. Daniel enjoys spending
time with his wife, Mary, and his new baby daughter, Hadassah. You can reach Daniel Robbins at drobbins@gentoo.org. |
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