Editing Tmpfs (section)

== Semantics ==
Everything stored in tmpfs is temporary in the sense that no files will be directly created on [[non-volatile storage]] such as a [[hard drive]] (although [[swap space]] is used as backing store according to the [[page replacement]] policy of the operating system). On [[Reboot (computer)|reboot]], everything in tmpfs will be lost.

The memory used by tmpfs grows and shrinks to accommodate the files it contains.

Many Unix [[distribution (software)|distribution]]s enable and use tmpfs by default for the {{mono|[[/tmp]]}} branch of the file system or for [[Shared memory (interprocess communication)|shared memory]]. This can be observed with {{mono|[[df (Unix)|df]]}} as in this example:

 Filesystem     1K-blocks   Used Available Use% Mounted on 
 tmpfs            1686428      0   1686428   0% /dev/shm 
 tmpfs             674572   1808    672764   1% /run 
 tmpfs               1024      0      1024   0% /run/credentials/systemd-journald.service 
 tmpfs            1686428   1628   1684800   1% /tmp 
 tmpfs               1024      0      1024   0% /run/credentials/getty@tty1.service 
 tmpfs               1024      0      1024   0% /run/credentials/getty@tty3.service 
 tmpfs             337284     32    337252   1% /run/user/0 
 tmpfs               1024      0      1024   0% /run/credentials/getty@tty4.service 
 tmpfs             337284 280464     56820  84% /run/user/1000

Some Linux distributions (e.g. [[Debian]]) do not have a tmpfs mounted on {{mono|[[/tmp]]}} by default; in this case, files under {{mono|/tmp}} will be stored in the same file system as {{mono|/}}.

And on almost all Linux distributions, a tmpfs is mounted on {{mono|/run/}} or {{mono|/var/run/}} to store temporary run-time files such as [[Process identifier#Pidfile|PID files]] and [[Unix domain sockets]].