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mount_fdesc(8) [netbsd man page]

MOUNT_FDESC(8)						    BSD System Manager's Manual 					    MOUNT_FDESC(8)

mount_fdesc -- mount the file-descriptor file system SYNOPSIS
mount_fdesc [-o options] fdesc mount_point DESCRIPTION
The mount_fdesc command attaches an instance of the per-process file descriptor namespace to the global filesystem namespace. The conven- tional mount point is /dev and the filesystem should be union mounted in order to augment, rather than replace, the existing entries in /dev. The directory specified by mount_point is converted to an absolute path before use. This command is normally executed by mount(8) at boot time. The options are as follows: -o Options are specified with a -o flag followed by a comma separated string of options. See the mount(8) man page for possible options and their meanings. The contents of the mount point are fd, stderr, stdin, stdout and tty. fd is a directory whose contents appear as a list of numbered files which correspond 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 existing descriptor, the call: fd = open("/dev/fd/0", mode); and the call: fd = fcntl(0, F_DUPFD, 0); are equivalent. The files /dev/stdin, /dev/stdout and /dev/stderr appear as symlinks to the relevant entry in the /dev/fd sub-directory. Opening them is equivalent to the following calls: fd = fcntl(STDIN_FILENO, F_DUPFD, 0); fd = fcntl(STDOUT_FILENO, F_DUPFD, 0); fd = fcntl(STDERR_FILENO, F_DUPFD, 0); Flags to the open(2) call other than O_RDONLY, O_WRONLY and O_RDWR are ignored. The /dev/tty entry is an indirect reference to the current process's controlling terminal. It appears as a named pipe (FIFO) but behaves in exactly the same way as the real controlling terminal device. FILES
/dev/fd/# /dev/stdin /dev/stdout /dev/stderr /dev/tty SEE ALSO
mount(2), unmount(2), tty(4), fstab(5), mount(8) HISTORY
The mount_fdesc utility first appeared in 4.4BSD. BUGS
This filesystem may not be NFS-exported. BSD
March 27, 1994 BSD

Check Out this Related Man Page

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

devfs -- device file system SYNOPSIS
devfs /dev devfs rw 0 0 DESCRIPTION
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 environ- ment, 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. FILES
/dev The normal devfs mount point. EXAMPLES
To mount a devfs volume located on /mychroot/dev: mount -t devfs devfs /mychroot/dev SEE ALSO
fdescfs(5), devfs(8), mount(8) HISTORY
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. AUTHORS
The devfs manual page was written by Mike Pritchard <>. BSD
February 9, 2012 BSD
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