Five of the top 10 most downloaded distributions on Distrowatch use the Debian package system. It has developed a rich infrastructure of utilities — not just the core commands apt-get and dpkg, but also such less well-known commands as apt-cache, apt-spy, and apt-listbugs.
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These scripts join a host of graphical front ends to apt-get and GUI tools for searching package repositories. However, because efficient package management is still done at the command line, they have a relevance that many command lines tools lack today. Some are simple, some are specific to one distribution (usually Ubuntu), and you might need to modify them before they suit your needs. However, all can be surprisingly useful if you believe in making hands-on decisions about the contents of your system instead of relying on the update applet in your notification tray. Here are three excellent examples.