man4/null.4

   1 .\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
   2 .\"     Fri Apr  2 11:32:09 MET DST 1993
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  23 .\" Modified Sat Jul 24 17:00:12 1993 by Rik Faith (faith@cs.unc.edu)
  24 .TH NULL 4 2009-02-23 "Linux" "Linux Programmer's Manual"
  25 .SH NAME
  26 null, zero \- data sink
  27 .SH DESCRIPTION
  28 Data written to a \fBnull\fP or \fBzero\fP special file is discarded.
  29 .PP
  30 Reads from the \fBnull\fP special file always return end of file (i.e.,
  31 .BR read (2)
  32 returns 0), whereas
  33 reads from \fBzero\fP always return bytes containing zero (\e0 characters).
  34 .LP
  35 \fBnull\fP and \fBzero\fP are typically created by:
  36 .RS
  37 .sp
  38 mknod \-m 666 /dev/null c 1 3
  39 .br
  40 mknod \-m 666 /dev/zero c 1 5
  41 .br
  42 chown root:root /dev/null /dev/zero
  43 .RE
  44 .SH FILES
  45 .I /dev/null
  46 .br
  47 .I /dev/zero
  48 .SH NOTES
  49 If these devices are not writable and readable for all users, many
  50 programs will act strangely.
  51 .SH SEE ALSO
  52 .BR chown (1),
  53 .BR mknod (1),
  54 .BR full (4)