### “Private” installations of files

It sometimes happens that you need a new version of some macro package or font, but that the machine you use is maintained by someone who’s unwilling to update and won’t give you privileges to do the job yourself. A “temporary” installation is sometimes the correct approach, but if there’s the slightest chance that the installation will be needed on more than one project, temporary installations aren’t right.

In circumstances where you have plenty of quota on backed-up media, or adequate local scratch space, the correct approach is to create a private installation of (La)TeX which includes the new stuff you need; this is the ideal, but is not generally possible.

So, since you can’t install into the public `texmf` tree, you have to install into a texmf of your own; fortunately, the TDS standard allows for this, and teTeX 2.0 actually makes provision for it, defining an internal variable `HOMETEXMF` which points to the directory $HOME/texmf. (TeTeX 1.0 had the definition, but suppressed it with comment markers.)

So, install your new package (or whatever) in the correct place in a tree based on $HOME/texmf, and generate an index of that tree

>     texhash $HOME/texmf

(the argument specifies which tree you are indexing: it’s necessary since you don’t, by hypothesis, have access to the main tree, and texhash without the argument would try to write the main tree.

There are two wrinkles to this simple formula: first, the installation you’re using may not define `HOMETEXMF` (teTeX 1.0 didn’t, for example), and second, there may be some obstruction to using $HOME/texmf as the default name. In either case, a good solution is to have your own texmf.cnf — an idea that sounds more frightening that it actually is. The installation’s existing file may be located with the command:

>     kpsewhich texmf.cnf

Take a copy of the file and put it into a directory of your own; this could be any directory, but an obvious choice is the web2c directory of the tree you want to create, i.e., $HOME/texmf/web2c or the like. Make an environment variable to point to this directory:

>     TEXMFCNF=$HOME/texmf/web2c
>     export TEXMFCNF

(for a Bourne shell style system), or

>     setenv TEXMFCNF $HOME/texmf/web2c

(for a C-shell style system). Now edit the copy of texmf.cnf

There will be a line in the existing file that defines the tree where everything searches; the simplest form of the line is:

>     TEXMF = !!$TEXMFMAIN

but, as teTeX 1.0 is distributed, there are several alternative settings behind comment markers (“`%`”), and the person who installed your system may have left them there. Whatever, you need to modify the line that’s in effect: change the above to three lines:

>     HOMETEXMF = $HOME/texmf
>     TEXMF = {$HOMETEXMF,!!$TEXMFMAIN}
>     % TEXMF = !!$TEXMFMAIN

the important point being that `$HOMETEXMF` must come before whatever was there before, inside the braces. For example, if the original was

>     TEXMF = {!!$LOCALTEXMF,!!$TEXMFMAIN}

it should be converted to:

>     HOMETEXMF = $HOME/texmf
>     TEXMF = {$HOMETEXMF,!!$LOCALTEXMF,!!$TEXMFMAIN}
>     % TEXMF = {!!$LOCALTEXMF,!!$TEXMFMAIN}

(retaining the original, as a comment, is merely an aide-memoir in case you need to make another change, later). The `!!` signs tell the file-searching library that it should insist on a texhash-ed directory tree; if you can count on yourself remembering to run texhash on your new tree every time you change it, then it’s worth adding the marks to your tree:

>     TEXMF = {!!$HOMETEXMF,!!$LOCALTEXMF,!!$TEXMFMAIN}

as this will make (La)TeX find its files marginally faster.

Having made all these changes, (La)TeX should “just use” files in your new tree, in preference to anything in the main tree — you can use it for updates to packages in the main tree, as well as for installing new versions of things.

This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=privinst