tmpfs is a memory based file system which uses kernel resources relating to the VM system and page cache as a file system.

mount attaches a tmpfs file system to the file system hierarchy at the pathname location mount_point, which must already exist. If mount_point has any contents prior to the mount operation, these remain hidden until the file system is once again unmounted. The attributes (mode, owner, and group) of the root of the tmpfs filesystem are inherited from the underlying mount_point, provided that those attributes are determinable. If not, the root's attributes are set to their default values.

The special argument is usually specified as swap but is in fact disregarded and assumed to be the virtual memory resources within the system.

-o specific_options

Specify tmpfs file system specific options in a comma-separated list with no intervening spaces. If invalid options are specified, a warning message is printed and the invalid options are ignored. The following options are available:

size=sz

The sz argument controls the size of this particular tmpfs file system. If the argument is has a `k' suffix, the number will be interpreted as a number of kilobytes. An `m' suffix will be interpreted as a number of megabytes. No suffix is interpreted as bytes. In all cases, the actual size of the file system is the number of bytes specified, rounded up to the physical pagesize of the system.

suid | nosuid

Allow or disallow setuid execution. The default is suid.

xattr | noxattr

Allow or disallow the creation and manipulation of extended attributes. The default is xattr. See fsattr(5) for a description of extended attributes.

-O

Overlay mount. Allow the file system to be mounted over an existing mount point, making the underlying file system inaccessible. If a mount is attempted on a pre-existing mount point without setting this flag, the mount will fail, producing the errordevice busy.

/etc/mnttab

table of mounted file systems

See attributes(5) for descriptions of the following attributes:

mount(1M), mkdir(2), mount(2), open(2), umount(2), mnttab(4), attributes(5), fsattr(5), tmpfs(7FS)

If the directory on which a file system is to be mounted is a symbolic link, the file system is mounted on the directory to which the symbolic link refers, rather than on top of the symbolic link itself.