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FDESCFS(5)		  FreeBSD File Formats Manual		    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.

     Note: /dev/fd/0, /dev/fd/1	and /dev/fd/2 files are	created	by default
     when devfs	alone is mounted.  fdescfs creates entries for all file
     descriptors opened	by the process.

FILES
     /dev/fd/#

EXAMPLES
     To	mount a	fdescfs	volume located on /dev/fd:

	   mount -t fdescfs null /dev/fd

SEE ALSO
     devfs(5), mount(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 manual page written by Jan-Simon Pendry.

FreeBSD	10.1		      September	18, 2010		  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=fdescfs&manpath=FreeBSD+10.1-RELEASE>

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