PV208 Advanced Topics of Linux Administration jaro 2008
Jméno: Miloš Jakubíček, UCO: 172962 Login: xjakub
Comparison of binary package formats
Purpose of binary packages
The general purpose of binary packages (no matter what format they use), or
to be more precise, package management systems, is to provide a prebuilt
software including related metainformation in a from that can be used to
enable the users and administrators to easily maintain (i. e. install, upgrade,
remove etc.) the systems and applications programs so that the system
remains consistent and its resources are used in a efficient way.
To achieve this, several standard methods are in use such as centralized
package repositories, dependencies detection mechanisms, automated updates
etc.
Binary package formats
There are various package formats which differ in their internal structure,
features or available functional overlays for yet advanced management, but
probably most widespread are RPM, deb and TGZ formats.
The RPM (the abbreviation stands for Redhat package management
according to the original vendor) format is used e. g. in SUSE/openSUSE,
Mandriva, CentOS and of course also RHEL and Fedora.
The deb(ian) format can be found especially on Debian-based distributions
such as Debian or Ubuntu and TGZ is actually not a standardized package
format as there are several (in most cases smaller) distributions (ArcliLinux,
Slackware, ...) which use tar&gzip to store their binary packages (in wide
range of formats).
In this paper, I would like to concentrate on the comparison between deb
and RPM format as these formats are most widespread nowadays and provide
the richest features. There is also a conversion tool between RPM and deb
called alien under development.
RPM
A standard way of packaging a program using RPM is to create a SPEC file
containing all the metainformation about the package such as name, version,
release (often abbreviated as N-V-R), runtime and buildtime dependencies,
various installation scripts (called scriptlets) or triggers (event-driven scripts
which can be executed when a specific action of another package occurs - like
installation, update, uninstallation, ...) etc.
Further, an SRPM (source RPM) is created from the SPEC file and all
source files which can be used to easily build the package or distribute the
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PV208 Advanced Topics of Linux Administration jaro 2008
Jméno: Miloš Jakubíček, UCO: 172962 Login: xjakub
package sources. From this SRPM one or more final RPMs are created to be
installed on the target systems. There is also useful program for automated
checking well-formed SPEC files and RPMS called rpmlint.
deb
The deb package structure consist of three main components: first it is the
debian-binary file containing the format version number, second, there is
a control.tar.gz package entailing all the metainformation about the package
similar to the RPM SPEC file, however separated into many files (such as
the control file with general metainformation or installation scripts which are
each in a separate file too).
Finally as third, there is a data.tar.gz package where all the binaries
and other applications programs files are stored. The counterpart of RPM's
rpmlint is lintian.
Comparison
First of all, I should anticipate that there are several aspects which are hard
to compare but important to consider. One of them is that each distribution
usually defines a more or less precise set of packaging rules which influence
the usability of their packaging systems in a big way. Moreover, users usually
do not choose their distribution according to the package management system
it uses and although it would be technically possible to use any of the package
management systems on every distribution, there are hardly more users doing
it.
From these (and yet more) reasons Ell just point out some pros and cons
of both RPM and deb package formats.
* RPM
+ DeltaRPM which saves users traffic by downloading only deltas (diffs)
between package versions
+ GPG signed packages
+ very good support for multilib (e. g. both 32bit and 64bit) systems
+ proper autogeneration of runtime dependencies in most of the cases
- no way to handle suggested (not necessary) dependencies
- non-standard format (rpm2cpio is needed for extraction)
- rich features mean less simple design
* deb
+ suggested dependencies
+ package priorities used to classify packages by their importance
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PV208 Advanced Topics of Linux Administration
Jméno: Miloš Jakubíček, UČO: 172962
jaro 2008
Login: xjakub
+ standard format (tar)
+ some developers appreciate decentralized design of stored metainfor-
mation
- no direct multilib support
- no file dependencies
Conclusion
During my presentation and subsequent discussion, there were several valuable
notices from my colleagues that I highly appreciate. Two of them I listed
below:
* Although the deb packages can signed using GPG, this option is not
used presently in Debian.
* Although the deb package format intended to be desktop-based and
therefore it is interactive whereas the RPM package format intended to
be server-based and as such it is strictly non-interactive, surprisingly in
these days RPM is used rather on desktops than servers.
Reference
* DEB:
http
http
http
http
en.wikipedia.org/wiki/Deb_(file_format)
tldp.org/HOWTO/html_single/Debian-Binary-Package-Building-HOWTO/
www.linuxdevices.com/articles/AT8047723203.html
www.debian.org/doc/FAQ/ch-pkg_basics.en.html
RPM
http
http
http
http
http
http
'www.rpm.org
/en.wikipedia.org/wiki/RPM_Package_Manager
/docs.fedoraproject.org/drafts/rpm-guide-en/
_enetikayos.com/code/repos/rpm-tutorial/trunk/rpm-tutorial.html
/www.ibm.com/developerworks/library/l-rpml/
/ www.abclinuxu.cz/clanky/navody/rukovet-balice-rpm-i-uvod
TGZ:
http://www.abclinuxu.cz/clanky/system/balickovaci-system-arch-linuxu-l-format-
balicku
Others:
plkárna FL thread Distro showdown let your voices be heard (21.9.2007)
http
http
http
/kitenet.net/ joey/pkg-comp/
/linux.die.net/man/1/alien
/www.howtoforge.com/converting_ rpm_to_deb_with_alien
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