title: What happened to the TMP environment variable?
body: <p>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.</p>
  
  <p>Today, I discovered that my Ubuntu install does not have that environment variable at all.</p>
  
  <p>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.</p>
  
  <p>Is that still the case?</p>