FDESCFS(5)

NAME

     fdescfs -- file-descriptor file system

SYNOPSIS

     fdescfs /dev/fd fdescfs rw 0 0

DESCRIPTION

     The file-descriptor file system, or fdescfs, provides access to the per-
     process file descriptor namespace in the global file system namespace.
     The conventional mount point is /dev/fd.

     The file system's contents appear as a list of numbered files which cor-
     respond to the open files of the process reading the directory.  The
     files /dev/fd/0 through /dev/fd/# refer to file descriptors which can be
     accessed through the file system.	If the file descriptor is open and the
     mode the file is being opened with is a subset of the mode of the exist-
     ing descriptor, the call:

	   fd = open("/dev/fd/0", mode);

     and the call:

	   fd = fcntl(0, F_DUPFD, 0);

     are equivalent.

     Flags to the open(2) call other than O_RDONLY, O_WRONLY and O_RDWR are
     ignored.

FILES

     /dev/fd/#

SEE ALSO

     mount_devfs(8), mount_fdescfs(8)

HISTORY

     The fdescfs file system first appeared in 4.4BSD.	The fdescfs manual
     page first appeared in FreeBSD 2.2.

AUTHORS

     The fdescfs manual page was written by Mike Pritchard <mpp@FreeBSD.org>,
     and was based on the mount_fdescfs(8) manual page written by Jan-Simon
     Pendry.