mknod - make block or character special files


     mknod [options] name {bc} major minor
     mknod [options] name p

     GNU options (shortest form):  [-m mode] [--help] [--version]


     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

          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


     -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.


          Print a usage message on standard output and exit  suc-

          Print version information on standard output, then exit

     --   Terminate option list.


     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.


     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     and and .  Report
     bugs in the program to


     chmod(1), mkfifo(1), mknod(2)