NULL(4)                   Linux Programmer's Manual                  NULL(4)

NAME         top

       null, zero - data sink

DESCRIPTION         top

       Data written to the /dev/null and /dev/zero special files is
       discarded.

       Reads from /dev/null always return end of file (i.e., read(2) returns
       0), whereas reads from /dev/zero always return bytes containing zero
       ('\0' characters).

       These devices are typically created by:

           mknod -m 666 /dev/null c 1 3
           mknod -m 666 /dev/zero c 1 5
           chown root:root /dev/null /dev/zero

FILES         top

       /dev/null
       /dev/zero

NOTES         top

       If these devices are not writable and readable for all users, many
       programs will act strangely.

       Since Linux 2.6.31, reads from /dev/zero are interruptible by
       signals.  (This change was made to help with bad latencies for large
       reads from /dev/zero.)

SEE ALSO         top

       chown(1), mknod(1), full(4)

COLOPHON         top

       This page is part of release 4.15 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                            2015-07-23                          NULL(4)

Pages that refer to this page: full(4),  dmsetup(8)

Copyright and license for this manual page

HTML rendering created 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.