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I've known about apt-cache for quite some time, but only yesterday stumbled on apt-file.

My question is, given this kind of output from the two...

ttsiod@avalon ~
$ apt-cache search setxkb
x11-xkb-utils - X11 XKB utilities
xfce4-xkb-plugin - xkb layout switch plugin for the Xfce4 panel

ttsiod@avalon ~
$ apt-file find setxkb
fish: /usr/share/fish/completions/setxkbmap.fish
fish: /usr/share/fish/functions/__fish_complete_setxkbmap.fish
x11-xkb-utils: /usr/bin/setxkbmap
x11-xkb-utils: /usr/share/man/man1/setxkbmap.1.gz
xmanpages-ja: /usr/share/man/ja/man1/setxkbmap.1.gz
zsh: /usr/share/zsh/functions/Completion/X/_setxkbmap
zsh-beta: /usr/share/zsh-beta/functions/Completion/X/_setxkbmap
zsh-common: /usr/share/zsh/functions/Completion/X/_setxkbmap

...why would one bother with apt-cache? Isn't apt-file superior in every way?

I am probably missing something.

EDIT: The reason I am asking is because apt-file reported MORE packages than apt-cache. I only use apt-cache for the use case "I need tool/manpage/whatever named foo - which packages contain foo?" and it seems that apt-file seems to do everything apt-cache does, but better - it reports more packages (apt-cache MISSES some), and it also shows the filenames involved.

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    They perform two completely separate tasks. The apt-cache search function is looking for packages within repositories. apt-file find is looking for files within your currently installed packages.
    – bsd
    Feb 10, 2014 at 10:55
  • I think that both apt-cache and apt-file don't look at the currently installed packages - they look at all of them. As you can see in the cmd above, apt-file in fact reported MORE matches than apt-cache (and I definitely don't have "fish" installed) - hence my question, about why one would prefer apt-cache instead of apt-file.
    – ttsiodras
    Feb 10, 2014 at 11:00
  • That depends on how the apt-file cache was built. By default it only builds a cache of packages that are installed. It has other options that lets it get contents from apt-sources.
    – bsd
    Feb 10, 2014 at 11:05
  • I installed it (with "apt-get install apt-file") and then used "apt-file update". I used no custom options... and the manpage for update says: "Resynchronize the package contents from their sources. The lists of the contents of packages are fetched from the locations specified in /etc/apt/sources.list".
    – ttsiodras
    Feb 10, 2014 at 11:13

1 Answer 1

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apt-cache queries a database of available packages and their metadata (installation source, version, dependencies, description, etc.).

apt-file queries a database of available packages and the files they contain.

The only information in common between these databases is that they both list available package names.

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  • The reason I am asking is because apt-file reported MORE packages than apt-cache. I only used apt-cache for the use case "I need tool/manpage/whatever named foo - which packages contain foo?" and it seems that apt-file seems to do everything apt-cache does, but better - it reports more packages (apt-cache MISSES some), and it also shows the filenames involved.
    – ttsiodras
    Feb 11, 2014 at 13:19
  • @ttsiodras apt-cache search searches package names and descriptions. apt-file search searches the list of file names. So if you're looking for the package containing a command with a certain name, apt-file has the information. If you're looking for a package about a certain topic, apt-cache has the information. Feb 11, 2014 at 14:32
  • Thanks, since I am always looking for packages based on contained files, indeed I was using the wrong tool. apt-file from now on!
    – ttsiodras
    Feb 11, 2014 at 14:43

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