June 23, 2011, 5:21 a.m.
posted by char
Querying the Package Management Database
The RPM package management database is an essential source of information about your system. The database is created when the system is installed and is updated whenever packages are added or removed.
As RPM packages are installed on your system, the metadata for those packages is stored in a database that can be queried. If you have a mystery file on your system and want to know where it came from, or want to know which version of a package is installed, or what a package does, an RPM query can answer your question in a few seconds.
How Do I Do That?
The rpm program provides access to the RPM database. The -q option enables query mode.
The default query takes a package name and tells you whether it is installed and, if so, which version is installed:
$ rpm -q selmyscan package selmyscan is not installed $ rpm -q httpd httpd-2.0.54-10.2
More advanced queries use two different sets of arguments: one to control which packages are reported in the output, and one to control what is reported about the selected packages.
Figure describes the most commonly used options for selecting packages.
For example, to find out which package installed the file /usr/lib/libcdda_interface.so:
$ rpm -qf /usr/lib/libcdda_interface.so cdparanoia-libs-alpha9.8-25
$ rpm -q --whatprovides smtpdaemon sendmail-8.13.4-2 postfix-2.2.2-2
Sometimes, though, you need more information than the name and version number of the packages selected. Figure lists the most common query output options.
When output options and selection options are combined, rpm becomes a very powerful tool. For example, to see the description of the package that installed /etc/mail/access:
$ rpm -qif /etc/mail/access Name : sendmail Relocations: (not relocatable) Version : 8.13.4 Vendor: Red Hat, Inc. Release : 2 Build Date: Fri 06 May 2005 08:35:13 AM EDT Install Date: Mon 29 Aug 2005 12:46:19 AM EDT Build Host: decompose.build.redhat.com Group : System Environment/Daemons Source RPM: sendmail-8.13.4-2.src.rpm Size : 1332268 License: Sendmail Signature : DSA/SHA1, Fri 20 May 2005 01:44:43 PM EDT, Key ID b44269d04f2a6fd2 Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla> Summary : A widely used Mail Transport Agent (MTA). Description : The Sendmail program is a very widely used Mail Transport Agent (MTA). MTAs send mail from one machine to another. Sendmail is not a client program, which you use to read your email. Sendmail is a behind-the-scenes program which actually moves your email over networks or the Internet to where you want it to go. If you ever need to reconfigure Sendmail, you will also need to have the sendmail.cf package installed. If you need documentation on Sendmail, you can install the sendmail-doc package.
$ rpm -qlf /usr/lib/libcdda_interface.so /usr/lib/libcdda_interface.so /usr/lib/libcdda_interface.so.0 /usr/lib/libcdda_interface.so.0.9.8 /usr/lib/libcdda_paranoia.so /usr/lib/libcdda_paranoia.so.0 /usr/lib/libcdda_paranoia.so.0.9.8
Or to see those files along with the package name:
$ rpm -qf --filesbypkg /usr/lib/libcdda_interface.so cdparanoia-libs /usr/lib/libcdda_interface.so cdparanoia-libs /usr/lib/libcdda_interface.so.0 cdparanoia-libs /usr/lib/libcdda_interface.so.0.9.8 cdparanoia-libs /usr/lib/libcdda_paranoia.so cdparanoia-libs /usr/lib/libcdda_paranoia.so.0 cdparanoia-libs /usr/lib/libcdda_paranoia.so.0.9.8
To see all of the other capabilities provided by the package that provides the capability perl:
$ rpm -q --whatprovides perl --provides APItest.so B.so Base64.so Byte.so ByteLoader.so ...(Lines snipped)... perl(warnings::register) = 1.00 re.so scalar.so shared.so threads.so via.so perl = 3:5.8.6-15
To see the scripts that will be triggered by removing sendmail:
$ rpm -q --triggeredby sendmail --triggers triggerpostun scriptlet (using /bin/sh) -- sendmail < 8.10.0 /sbin/chkconfig --add sendmail triggerpostun scriptlet (using /bin/sh) -- sendmail < 8.11.6-11 /usr/sbin/alternatives --auto mta
To list the files in the uninstalled RPM package file a52dec-0.7.4-4.fr.i386.rpm:
$ rpm -qlp a52dec-0.7.4-4.fr.i386.rpm /usr/bin/a52dec /usr/bin/extract_a52 /usr/share/doc/a52dec-0.7.4 /usr/share/doc/a52dec-0.7.4/AUTHORS /usr/share/doc/a52dec-0.7.4/COPYING /usr/share/doc/a52dec-0.7.4/ChangeLog /usr/share/doc/a52dec-0.7.4/NEWS /usr/share/doc/a52dec-0.7.4/README /usr/share/doc/a52dec-0.7.4/TODO /usr/share/doc/a52dec-0.7.4/liba52.txt /usr/share/man/man1/a52dec.1.gz /usr/share/man/man1/extract_a52.1.gz
If that RPM were on a remote web server or FTP server, you could substitute the URI for the filename:
$ rpm -qlp \ftp://ftp.ntua.gr/pub/video/videolan/testing/vlc-0.7.0-test1/rpm/rh9-fc1/rh9-fc1/vlc/a52dec-0.7.4-4.fr.i386.rpm /usr/bin/a52dec /usr/bin/extract_a52 ...(Lines snipped)...
How Does It Work?
RPM packages are compressed archives of files with metadata. The archive is in cpio format, with gzip compression; the metadata is stored in a flexible, easily extensible format for forward- and (limited) backward-compatibility.
When a package is installed, the metadata is copied to the RPM database. If this were not done, it would be necessary to keep all of the original package files in storage to find out about installed packages, and queries would run very slowly because hundreds of files would have to be individually opened and searched.
The RPM database is stored in several files in /var/lib/rpm. These databases are in the indexed DBM/GDBM format, which is also used for other configuration databases such as /etc/aliases.db; this indexed format permits high-speed searching.
...converting an RPM to a plain archive?
$ rpm2cpio gnome-applet-gvid-0.3-1.i386.rpm > gnome-applet.cpio
You can then use cpio to examine or install the archive. Note that rpm2cpio removes the gzip compression on the archive contents, so the resulting file is larger than the original RPM file. If you want to extract a specific file from the archive, you can use the cpio command. However, this is not a good way to install the file, since none of the scripts and other install-time actions will be performed:
$ rpm2cpio gnome-applet-gvid-0.3-1.i386.rpm | cpio -idv
...a damaged RPM database?
Use rpm with the -- rebuilddb option to recover from most forms of database corruption (this can take a while to run). You will need to run it as root:
# rpm --rebuilddb
Where Can I Learn More?