I run df -h and found on my Debian Squeeze two tmpfs directory,
tmpfs 1.5G 0 1.5G 0% /lib/init/rw tmpfs 1.5G 0 1.5G 0% /dev/shm
Then, I added a line in my /etc/fstab as following,
tmpfs /tmp tmpfs size=1g 0 0
and I rebooted Debian and found /tmp mounted successfuly.
tmpfs 1.0G 236K 1.0G 1% /tmp tmpfs 1.5G 0 1.5G 0% /lib/init/rw tmpfs 1.5G 0 1.5G 0% /dev/shm
My physical memory's size is 3GB. I wonder: Is the three tmpfs either all resided on the memory(Is that possible?) or extended to the swap?