How to find a package name by a command name?

Question

Often I'm trying to use a command in my document and it doesn't compile, because I haven't included the package I need for it. Of course, I know, that I can try to google it, but Google often finds some manuals and usage examples without package information (but this is probably because I don't know, how to google better). In all the cases I've succeeded in determining of the package name, but wasted more than 30 minutes in many of them.

Which ways would you advise to search for package name? Which hints would you suggest?

Answer 1

$ grep -r '\\commandname' $TEXMF/tex/latex

Answer 2

If the command is for a symbol, I would look it up in the comprehensive symbols list or in Detexify, both let you know which package you need to load in order to get the symbol.

If the command is for a specific topic or feature, I would try to google for “latex feature” or even “ctan feature” instead of searching for the particular command.

Answer 3

Since April 2023 there is TeXFindPkg, a tool that does it!

On your terminal type:

texfindpkg query [<name>]

where <name> could be a file name, a command name, or an environment name.

The tool was created to install TeX packages and their dependencies by file names, command names, or environment names.

Its general usage is

texfindpkg <action> [<name>]

where <action> could be install or query, and <name> could be what is listed above.
For example:

texfindpkg install array.sty
texfindpkg install \fakeverb
texfindpkg install {frame}
texfindpkg query array.sty
texfindpkg query \fakeverb
texfindpkg query {frame}

TeXFindPkg supports both TeXLive and MiKTeX distributions.

More info on https://ctan.org/pkg/texfindpkg.

Answer 4

in general, ctan doesn't have this information (except in the sources of the packages themselves, of course). the catalogue package descriptions (already mentioned) do occasionally mention command names, but they're not a reliable source of this information.

there's no particular reason why ctan shouldn't hold the information, but collecting it would take absolutely ages. one would have to be careful about duplicates (mentions above of graphics vs graphicx for the same command, for example), and the simple volume of packages is going to make it an unwieldy operation.

(note that commands in latex itself aren't a problem, in that they appear at least twice on the web anyway.)

Answer 5

You can try searching here for the command name in the package descriptions on CTAN.

Answer 6

Succinctly: Go back to where you learned about the command for the first time (be it a person or a web page) and see if he/she/it can tell you.

More verbosely (since I got a downvote on this answer I'm guessing it's because I came off as glib, sorry): you put that command in the document for a reason. Either somebody suggested it or you found a code snippet on a web page somewhere. That same person/page should also know what package needs to be included to make it work.

Example 1 You are following the advice of your colleague, let's call him...Martin. But because the conversation took place in the hallway you couldn't write down the actual code required.

"Hey, Martin, you remember how you told me I could use \snarfbbf to snarf the bumblefrack?"

"Yeah."

"Well, it doesn't work. It says the control sequence is undefined."

"Did you include the bbfrack package?"

"Oh, I get it. Thanks."

Example 2 Somebody (let's call him...Stefan) writes a blog post about snarfing bumblefracks in TeX documents. You copied-and-pasted a code snippet from part of the post. But because you didn't copy the preamble you have missed the required packages.

Go back to that web page, where either the complete document or a note about which packages are required should be there. If not, ask the blogger.