TeX Live package dependencies

In general, TL does not try to track package dependencies, since there is no reliable way to detect dependencies automatically. (That would mean installing packages during the TeX run, as MiKTeX does, and there are complications with doing this in TL.)

However, if you as the package author wish to specify dependencies, this can be done. We do not request this, and do not particularly recommend it, but since people have asked us, we've defined the following mechanism. Packages doing this must be uploaded to CTAN.

Provide a file named DEPENDS.txt (with that capitalization and extension) at the top level of your CTAN upload (sibling to your README file). A four-line example:

dep1
hard dep2
hard dep3 dep4
soft xedep # XeTeX only

The intent is for the file to be automatically processed. So its syntax must adhere to the following:

• Whitespace is ASCII space (0x20) and tab (0x09).
• Lines are terminated with ASCII linefeed (0x0a) possibly preceded by ASCII return (0x0d).
• Blank lines, consisting of only whitespace, are ignored.
• Leading and trailing whitespace on a line are ignored.
• Multiple whitespace characters are the same as one.
• Comments begin with # and continue to the end of line.
• Each non-blank line therefore consists of one or more whitespace-separated words.
• If the first word on a line is hard, soft, or package, all subsequent words are the arguments.
• If a line has only one word, hard is assumed (first line of example above).

• The arguments must be valid package names, as defined by CTAN. For example, that means they consist of all lowercase ASCII letters a-z, ASCII numbers 0-9, dash, underscore (very occasionally), and nothing else. If this is different from the TL package name, use the CTAN name anyway; we will convert, one way or another. If the package does not exist in TL at all, the depends file will be ignored.

• The hard directive means the following package(s) are always required. These will be converted into dependencies for tlmgr.

• The soft directive means the following package(s) may be needed, but are not required. As in the example above, perhaps they are only needed when running XeTeX (or some other specific engine). These must be listed as soft because not every installation wants or needs (for example) XeTeX. Similarly with packages that are only conditionally required, e.g., if some option to your package is specified. As far as tlmgr goes, soft dependencies are currently ignored, but they may serve as useful documentation. Your choice.

• The package directive must be followed by exactly one more word, and that word is the package name for which any following dependencies are applied. This is only useful in the extremely unusual case of two or more packages being distributed from a single CTAN directory; it's best to leave it out in the normal case.

• A DEPENDS.txt file is not required to have any directives. An empty or comment-only file is valid, though meaningless.

If experience shows that changes are necessary, we may extend the syntax in the future, but we don't expect to ever need to make an incompatible change.

If you have questions or suggestions, email tex-live@tug.org.