[SLL] Anybody have any idea of what I will typically break by initializing /tmp at bootup?

[Jeremy C. Reed]

To answer your question in your Subject: line...

Nothing should break. If anything breaks, then that software is broken. 

Some Unix operating systems use memory filesystems for /tmp so they are 
always clean at boot. And many operating systems clean /tmp automatically 
at boot. And many automatically clean /tmp periodically for old files.

In many cases, a /tmp directory is not even needed as a lot of software 
has configurations to choose their temp directory or honor TMP or TMPDIR 
environment variables.