What happened to the TMP environment variable?

Question

I always heard that the proper way to find the temporary folder on a UNIX machine was to look at the TMP environment variable. When writing code that worked on Windows as well as Linux, I would check for TEMP and TMP.

Today, I discovered that my Ubuntu install does not have that environment variable at all.

I know it seems you can always count on /tmp being there to put your temporary files in, but I understood that TMP was the way the user could tell you to put the temporary files someplace else.

Is that still the case?

Answer 1

You are probably thinking of TMPDIR.

This variable shall represent a pathname of a directory made available for programs that need a place to create temporary files.

Answer 2

A good way to create a temporary directory is using mktemp, e.g.

mktemp -d -t 

This way, you can even make sure, that your file names won't collide with existing files.

Answer 3

POSIX/FHS says that /tmp is the root for temporary files, although some programs may choose to examine $TEMP or $TMP instead.

Answer 4

Similar to what @Chris Lercher said, I find that this works for me:

dirname $(mktemp -u -t tmp.XXXXXXXXXX)

That won't actually create a temp file (because of the -u flag to mktemp) but it'll give you the directory that temp files would be written to. This snippet works on OSX and Ubuntu (probably other *nix too).

If you want to set it into a variable, do something like this:

TMPDIR=`dirname $(mktemp -u -t tmp.XXXXXXXXXX)`