Lack of memory on computers is less of a problem than it was in the past. Instead, the opposite problem is more common: In two or three terabytes, files can be easily hidden that could be deleted. If the misplaced files are package files, they can can become a security problem and interfere with the installation of new packages or, worse still, system updates.

In 2011, Raphaël Hertzog, the founder of Freexian, posted a series of five blogs with the running title of "Debian Cleanup Tips" that explains how to locate different types of misplaced files – mostly for packages – and deal with them [1]. Specifically, he mentions cruft (unneeded clutter), configuration files, obsolete packages, third-party packages, and broken packages. Hertzog's tips remain relevant today, so I thought it would be useful to summarize them for a general audience, adding my own comments such as where to obtain package information. Taken together, these tips form a maintenance routine that can be followed on any Debian or Debian-derived system.

Deleting Unused Packages

Security is strongest when only needed packages are installed. For security, or to free memory on a small filesystem, you may want to look up information about a package. This information can be found online [2] or on an installed system [3]. You may also want to check the last time a binary was accessed, using stat FILE, which shows the last time that a file was accessed, modified, or changed, as well as its birth (date of creation) (Figure 1). If a long-unused package is not essential, it might be a candidate for deletion using apt remove PACKAGE. Candidates for deletion are most likely to be found in /usr or sometimes /opt.

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