Refer the reader to fdesc(5) for detailed info on the fdesc filesystem.
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@ -73,98 +73,24 @@ See the
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man page for possible options and their meanings.
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.El
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.Pp
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The contents of the mount point are
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.Pa fd ,
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.Pa stderr ,
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.Pa stdin ,
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.Pa stdout
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and
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.Pa tty .
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.Pp
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.Pa fd
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is a directory whose contents
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appear as a list of numbered files
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which correspond to the open files of the process reading the
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directory.
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The files
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.Pa /dev/fd/0
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through
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.Pa /dev/fd/#
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refer to file descriptors which can be accessed through the file
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system.
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If the file descriptor is open and the mode the file is being opened
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with is a subset of the mode of the existing descriptor, the call:
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.Bd -literal -offset indent
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fd = open("/dev/fd/0", mode);
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.Ed
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.Pp
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and the call:
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.Bd -literal -offset indent
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fd = fcntl(0, F_DUPFD, 0);
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.Ed
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.Pp
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are equivalent.
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.Pp
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The files
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.Pa /dev/stdin ,
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.Pa /dev/stdout
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and
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.Pa /dev/stderr
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appear as symlinks to the relevant entry in the
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.Pa /dev/fd
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sub-directory.
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Opening them is equivalent to the following calls:
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.Bd -literal -offset indent
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fd = fcntl(STDIN_FILENO, F_DUPFD, 0);
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fd = fcntl(STDOUT_FILENO, F_DUPFD, 0);
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fd = fcntl(STDERR_FILENO, F_DUPFD, 0);
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.Ed
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.Pp
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Flags to the
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.Xr open 2
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call other than
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.Dv O_RDONLY ,
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.Dv O_WRONLY
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and
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.Dv O_RDWR
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are ignored.
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.Pp
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The
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.Pa /dev/tty
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entry is an indirect reference to the current process's controlling terminal.
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It appears as a named pipe (FIFO) but behaves in exactly the same way as
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the real controlling terminal device.
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See
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.Xr fdesc 5
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for a detailed description of the contents
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of the
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.Nm fdesc
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filesystem.
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.Sh FILES
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.Bl -tag -width /dev/stderr -compact
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.It Pa /dev/fd/#
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.It Pa /dev/stdin
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.It Pa /dev/stdout
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.It Pa /dev/stderr
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.It Pa /dev/tty
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.El
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.It Pa /dev
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Normal mount point for the
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.Nm fdesc
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filesystem.
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.Sh SEE ALSO
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.Xr mount 2 ,
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.Xr unmount 2 ,
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.Xr tty 4 ,
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.Xr fdesc 5 ,
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.Xr fstab 5 ,
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.Xr mount 8
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.Sh CAVEATS
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No
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.Pa .
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and
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.Pa ..
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entries appear when listing the contents of the
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.Pa /dev/fd
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directory.
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This makes sense in the context of this filesystem, but is inconsistent
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with usual filesystem conventions.
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However, it is still possible to refer to both
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.Pa .
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and
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.Pa ..
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in a pathname.
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.Pp
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This filesystem may not be NFS-exported.
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.Sh HISTORY
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The
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.Nm mount_fdesc
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