DEVFS(5)                     BSD File Formats Manual                    DEVFS(5)

     devfs — device 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

     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:

                     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.

     /dev       The normal devfs mount point.

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

           mount -t devfs devfs /mychroot/dev

     fdescfs(5), devfs(8), mount(8), make_dev(9)

     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 <>.

BSD                             February 9, 2012                             BSD