NAME
mknod - make block or character special files
SYNOPSIS
mknod [options] name {bc} major minor
mknod [options] name p
GNU options (shortest form): [-m mode] [--help] [--version]
[--]
DESCRIPTION
mknod creates a FIFO (named pipe), character special file,
or block special file with the specified name.
A special file is a triple (boolean, integer, integer)
stored in the filesystem. The boolean chooses between char-
acter special file and block special file. The two integers
are the major and minor device number.
Thus, a special file takes almost no place on disk, and is
used only for communication with the operating system, not
for data storage. Often special files refer to hardware dev-
ices (disk, tape, tty, printer) or to operating system ser-
vices (/dev/null, /dev/random).
Block special files usually are disk-like devices (where
data can be accessed given a block number, and e.g. it is
meaningful to have a block cache). All other devices are
character special devices. (Long ago the distinction was a
different one: I/O to a character special file would be
unbuffered, to a block special file buffered.)
The mknod command is what creates files of this type.
The argument following name specifies the type of file to
make:
p for a FIFO
b for a block (buffered) special file
c for a character (unbuffered) special file
The GNU version of mknod allows u (`unbuffered') as a
synonym for c.
When making a block or character special file, the major and
minor device numbers must be given after the file type (in
decimal, or in octal with leading 0; the GNU version also
allows hexadecimal with leading 0x). By default, the mode
of created files is 0666 (`a+rw') minus the bits set in the
umask.
OPTIONS
-m mode, --mode=mode
Set the mode of created directories to mode, which can
be symbolic as in chmod(1) and then uses the default
mode as the point of departure.
GNU STANDARD OPTIONS
--help
Print a usage message on standard output and exit suc-
cessfully.
--version
Print version information on standard output, then exit
successfully.
-- Terminate option list.
CONFORMING TO
POSIX does not describe this command as it is nonportable,
and recommends using mkfifo(1) to make FIFOs. SVID has a
command /etc/mknod with the above syntax, but without the
mode option.
NOTES
On a Linux system (version 1.3.22 or newer) the file
/usr/src/linux/Documentation/devices.tex contains a list of
devices with device name, type, major and minor number.
The present page describes mknod as found in the fileutils-
3.16 package; other versions may differ slightly. Mail
corrections and additions to aeb@cwi.nl and
aw@mail1.bet1.puv.fi and ragnar@lightside.ddns.org . Report
bugs in the program to fileutils-bugs@gnu.ai.mit.edu.
SEE ALSO
chmod(1), mkfifo(1), mknod(2)