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.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.TH null 4 (date) "Linux man-pages (unreleased)"
.SH NAME
null, zero \- data sink
.SH DESCRIPTION
Data written to the
.I /dev/null
and
.I /dev/zero
special files is discarded.
.P
Reads from
.I /dev/null
always return end of file (i.e.,
.BR read (2)
returns 0), whereas reads from
.I /dev/zero
always return bytes containing zero (\[aq]\[rs]0\[aq] characters).
.P
These devices are typically created by:
.P
.in +4n
.EX
mknod \-m 666 /dev/null c 1 3
mknod \-m 666 /dev/zero c 1 5
chown root:root /dev/null /dev/zero
.EE
.in
.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.
.P
Since Linux 2.6.31,
.\" commit 2b83868723d090078ac0e2120e06a1cc94dbaef0
reads from
.I /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)
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