Actually, I've been symlinking /tmp to /var/tmp ever since I use FreeBSD (4 years orso), never had any problems with it.
/tmp gets cleared every day by the
periodic(8) script
/etc/periodic/daily/110.clean-tmp, there are several options available you can set in
/etc/periodic.conf
Code:
# 110.clean-tmps
daily_clean_tmps_enable="NO" # Delete stuff daily
daily_clean_tmps_dirs="/tmp" # Delete under here
daily_clean_tmps_days="3" # If not accessed for
daily_clean_tmps_ignore=".X*-lock .X11-unix .ICE-unix .font-unix .XIM-unix"
daily_clean_tmps_ignore="$daily_clean_tmps_ignore quota.user quota.group"
# Don't delete these
daily_clean_tmps_verbose="YES" # Mention files deleted
You may also want to take a look at
/etc/defaults/periodic.conf