.\" Copyright (c) 1993 Michael Haardt (michael@moria.de),
.\"     Fri Apr  2 11:32:09 MET DST 1993
.\"
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.\" Modified Sat Jul 24 17:00:12 1993 by Rik Faith (faith@cs.unc.edu)
.TH NULL 4 2015-07-23 "Linux" "Linux Programmer's Manual"
.SH NAME
null, zero \- data sink
.SH DESCRIPTION
Data written to the
.IR /dev/null
and
.IR /dev/zero
special files is discarded.
.PP
Reads from
.IR /dev/null
always return end of file (i.e.,
.BR read (2)
returns 0), whereas reads from
.IR /dev/zero
always return bytes containing zero (\(aq\e0\(aq characters).
.LP
These devices are typically created by:
.RS
.sp
mknod \-m 666 /dev/null c 1 3
.br
mknod \-m 666 /dev/zero c 1 5
.br
chown root:root /dev/null /dev/zero
.RE
.SH FILES
.I /dev/null
.br
.I /dev/zero
.SH NOTES
If these devices are not writable and readable for all users, many
programs will act strangely.

Since Linux 2.6.31,
.\" commit 2b83868723d090078ac0e2120e06a1cc94dbaef0
reads from
.IR /dev/zero
are interruptible by signals.
(This change was made to help with bad latencies for large reads from
.IR /dev/zero .)
.SH SEE ALSO
.BR chown (1),
.BR mknod (1),
.BR full (4)