I seem to remember many releases ago playing with this, and there was a
config file to set /tmp to tmpfs. A quick google leads me to to look at
'man tmpfs' which says:
/tmp Previously configured using RAMTMP in /etc/default/rcS. Note that the
setting in /etc/default/rcS, if present, will still be used, but the
setting in /etc/default/tmpfs will take precedence if enabled.
Configured using RAMTMP, TMPFS_SIZE and TMP_SIZE. If desired, the
defaults may also be overridden with an entry in in /etc/fstab, for
example:
I also found a 10 year old debian-devel post [1] where it looks like
Debian we're thinking of making /tmp be in RAM by default. (I though it
was at some point, but could well be mistaken).