How do I determine callable commands provided by an installed Debian package?

Question

I'm a relatively new Linux user, so today I ran into an issue. I installed an emulator front-end ("visualboyadvance-gtk") from my distro's apt repository, but after it finished installing, I couldn't figure out what the terminal command for the program was. Generally, the terminal command and the package name are pretty close, so I've never run into this issue before. (In this case, the command ended up being 'gvba'; nothing like the name of the package in the repo..)

So, my question is: Is there a quick and easy way to determine the terminal command for any package that I've installed? I looked through the 'apt-cache show' information for that package, but there was nothing in it the actual terminal command. I'm guessing there must be a way to find that type of information with APT or dpkg or something..

Answer 1

I usually do

  dpkg -L packagename | grep -E '/s?bin/'

to get the list of everything "callable" that package offers.

The rule is simple: as per Debian policy (and the FHS) all programs callable by regular users (non-admin) must place their binaries (or links to them, usually symbolic) under /bin or /usr/bin¹, and all programs callable by sysadmins must place their binaries (or links to them) under /sbin or /usr/sbin¹.

Any local programs—not installed from packages, and therefore not part of "the system"—have to place their callable binaries under /usr/local/bin or /usr/local/sbin—these places are "yours", and you're guaranteed no package installed from official repositories will ever place/link a binary there.

If you run

echo $PATH

in your terminal as a regular user, you'll see /bin and /usr/bin and /usr/local/bin listed—that's where the shell looks for the non-builtin commands you ask it to run. The superuser will have "sbin" versions of these directories listed as well.

And finally one minor note: you can't—just by looking at the list of programs a package offers—determine which of them are command-line ("callable in a terminal") or GUI (requiring an X server to connect) because both kinds of programs are placed in the same hierarchy of directories. On the other hand, those GUI applications which wish to integrate into the desktop environment (such as GNOME, KDE, XFCE, LXDE etc) usually provide the so-called "desktop files" (ending with the .desktop extension) which give their program a descriptive title, a description of its purpose and state the way the application has to be called. These files are scanned by the desktop enviroment and are displayed in its "application menu" (or are otherwise used in a similar way). Hence if you're looking for this kind of programs, you might grep the output of dpkg -L for .desktop.

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¹ The distinction between the /usr and / hierarchies is subtle and currently debatable in the Linux-centric communities so let's not digress into discussing it.

Answer 2

The problem you have is that packages may include many commands, or (as in the case of libraries) none at all.

You can see the contents of the package with dpkg -L packagename. Anything the package has installed in /usr/bin will be runnable from the command line, although not all commands will give very sensible results.

You could also try searching the manpages -- man -k visualboyadvance might give you something useful.

Answer 3

Search here for your Package.

Then open the list of files.

Everything under /usr/bin/ is an executable you can use from your terminal.

In your case only gvba.