7: Software Management
7.1: Introduction
Methods
Synaptic is the recommended method for beginners to manipulate software packages, although other methods are also available and may be
required for certain situations.
Packages
Installing, removing, and upgrading software on MEPIS is accomplished through the Advanced Package Tool (APT) system. Software
is provided in the form of a package, a discrete, non-executable bundle of data that includes instructions for your package manager
about installation. They are stored on servers called repositories, and can be browsed, downloaded, and installed through special
client software called a package manager. The recommended package manager for MEPIS is Synaptic (see Section 7.2), though the graphical utility KPackage and the command-line utility apt-get are also included for those who prefer them (see Section 7.3).
The majority of packages have one or more dependencies, meaning that they have one or more packages that must also be
installed in order for them to work. The APT system is designed to automatically handle dependencies for you; in other words, when you
try to install a package whose dependencies aren't already installed, your APT package manager will automatically mark those dependencies
for installation as well.
Repositories
APT repositories (repos) are much more
than just web sites with downloadable software. The packages on repository sites are specially organized and indexed to be accessed through
a package manager, rather
than browsed directly. MEPIS Linux 7.0 comes with a set of enabled repositories that offer you both security and choice. If you are new to
MEPIS (and especially if you are new to Linux), it is recommended that you stick with the default repositories (though see Section 8.2).
For security reasons, these repositories are digitally signed, meaning that packages are authenticated with an encryption key to make sure
they are authentic. You can install packages without the key, but you will get a warning that they could not be authenticated. To get rid
of this warning and make sure your installations are secure, you need to install any keys not installed by default. Most repositories should
have a keyring package which installs the necessary keys (search keyring in Synaptic). Here are the most common:
- gnome-keyring
- debian-archive-keyring
- debian-multimedia-keyring
If you add other repositories aside from the default, see if they contain a keyring package, or check the repository's home page for
instructions on adding the key.
Repositories are most easily added, removed, or edited through Synaptic using the repository editor (Settings -->
Repositories). They can also be altered by hand, using as root any text editor to modify the list stored in
/etc/apt/sources.list.
Some repositories carry special labels:
- contrib, which depend on or are accessory to non-free packages.
- non-free, which do not meet the Debian free software guidelines (DFSG).
- security repository, which contains security-related updates only.
- backports repository, which contains packages from newer versions of Debian that have been backwards compiled for Debian 4.0
(“Etch,” the version SimplyMEPIS 7.0 is built with) to keep your OS up-to-date.
- MEPIS repository, which contains the special packages that make MEPIS what it is.
Tips
- Be sure to have only one package manager open at a time, or you will get an error message.
- MEPIS Linux 7.0 is binary-compatible with Etch. This means that software compiled to run on Etch should be able to be run without
modification on MEPIS Linux 7.0. Adding repostiories or installing packages designed for newer versions of Debian, Ubuntu, or Ubuntu
derivatives (including SimplyMEPIS 6.x) may cause system instability.
- In addition to dependencies, packages can also specify suggests and recommends. Recommends, unlike
“dependencies,” are not absolutely required, but should be installed along with the package in most circumstances.
Suggests are packages that enhance or compliment the package in question, but are in no way required. To see and/or mark
suggested or recommended packages, right-click the package and select mark suggested for install or mark
recommended for install, respectively.
- MEPIS Linux 7.0 includes a special desktop applet called APT-Notify, which is already in the kicker-bar of the
default desktop. Normally it appears as an empty yellow-brown box, but when updates are available a green arrow will appear on the box and
the number of available updates will appear below it. Click the icon to open Synaptic, click Mark all upgrades, and run the updates.
- If you plan to install software using methods other than APT (for instance, to get a newer version), make sure you purge any
versions that have been installed using Synaptic (right-click, Mark for Complete Removal) or apt-get in a terminal (type
dpkg --help for information). Since non-repository installations often put files in different locations than repository
installations, failing to remove the repository version can cause two conflicting versions to be installed side-by-side.
Troubleshooting
- Uninstall?: Occasionally, conflicts in package dependencies can cause the APT system to require the uninstallation of a
large number of important packages in order to install some other package. This is rare with the default configuration, but becomes
increasingly likely as you add unsupported repositories. BE VERY ATTENTIVE whenever installing a package would require
that others be removed! If a large number of packages are going to be removed, you may want to investigate another method of installing
this application.
- Keep?: When upgrading, you will often be informed that a new configuration file is available for a certain package, and be asked
whether you want to install the new version (a.k.a. “the package maintainer's version”) or keep your current version. The
safest answer to this question is usually keep the current version (N), which is also the default choice.
If the package in question is from a MEPIS Linux repository, it is recommended that you say “yes” (Y) instead.
- Broken packages: Occasionally, packages will fail to install because their install scripts fail one or more safety
checks; for instance, a package might try to overwrite a file that is part of another package, or require downgrading another package
due to dependencies. If you have an install or upgrade that is stuck on one of these errors, it is called a broken package. You
can fix this by opening Synaptic, click on the Custom button on the bottom of the left panel, then the entry
Broken, and right-click the package(s) to uninstall. You can also use dpkg or apt-get, consult
the documentation.
Links and Guides
