DEVFS(5) FreeBSD File Formats Manual DEVFS(5)


devfsdevice file system


devfs /dev devfs rw 0 0


The device file system, or devfs, provides access to kernel's device namespace in the global file system namespace. The conventional mount point is /dev.

The file system includes several directories, links, symbolic links and devices, some of which can also be written. In a chroot'ed environment, devfs can be used to create a new /dev mount point.

The mknod(8) tool can be used to recover deleted device entries under devfs.

The fdescfs(5) filesystem is an alternate means for populating /dev/fd. The character devices that both devfs and fdescfs(5) present in /dev/fd correspond to the open file descriptors of the process accessing the directory. devfs only creates files for the standard file descriptors 0, 1 and 2. fdescfs(5) creates files for all open descriptors.

The options are as follows:

-o options
Use the specified mount options, as described in mount(8). The following devfs file system-specific options are available:
ruleset= ruleset
Set ruleset number ruleset as the current ruleset for the mount-point and apply all its rules. If the ruleset number ruleset does not exist, an empty ruleset with the number ruleset is created. See devfs(8) for more information on working with devfs rulesets.


The normal devfs mount point.


To mount a devfs volume located on /mychroot/dev:

mount -t devfs devfs /mychroot/dev


The devfs file system first appeared in FreeBSD 2.0. It became the preferred method for accessing devices in FreeBSD 5.0 and the only method in FreeBSD 6.0. The devfs manual page first appeared in FreeBSD 2.2.


The devfs manual page was written by Mike Pritchard <mpp@FreeBSD.org>.
February 9, 2012 FreeBSD