Recently I discovered on Debian Wheezy that they are introducing /tmp automatically mounted as tmpfs. On current Debian Wheezy, this has been changed.
Check the old advisory
# man 5 rcS ... NOTE The EDITMOTD, RAMRUN and UTC variables are no longer used. The RAMLOCK, RAMSHM and RAMTMP variables have been moved to /etc/default/tmpfs; RAMSHM and RAMTMP settings in rcS are used (if set) for backward compatibility, but will be overridden by settings enabled in /etc/default/tmpfs. See tmpfs(5) for further details. The settings are not automatically migrated to /etc/default/tmpfs. Please update /etc/default/tmpfs appropriately. The UTC setting is replaced by the UTC or LOCAL setting in /etc/adjtime, and should have been migrated automatically. See hwclock(5) and hwclock(8) for further details on configuring the system clock.
Which is now handled within tmpfs(5).
# man 5 tmpfs ... RAMTMP Mount /tmp as a tmpfs. Defaults to no; set to yes to enable (/tmp will be part of the root filesystem if disabled). /tmp may also be configured to be a separate mount in /etc/fstab, which will override the RAMTMP setting.
So for gods sake, this is disabled by default now (# mount will tell you). If you require this to be enabled, set this accordingly in /etc/default/tmpfs – which is pretty nice, thanks Debian!
# vim /etc/default/tmpfs ... # mount /tmp as a tmpfs. Defaults to no; set to yes to enable (/tmp # will be part of the root filesystem if disabled). /tmp may also be # configured to be a separate mount in /etc/fstab. #RAMTMP=no # Size limits. Please see tmpfs(5) for details on how to configure # tmpfs size limits. #TMPFS_SIZE=20%VM #RUN_SIZE=10% #LOCK_SIZE=5242880 # 5MiB #SHM_SIZE= #TMP_SIZE=