/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:
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.
/dev/fd/#
/dev/stdin
/dev/stdout
/dev/stderr
/dev/tty