null(4) — Linux manual page

null(4)                 Kernel Interfaces 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)

Linux man-pages 6.04           2023-02-05                        null(4)

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

HTML rendering created 2023-06-24 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.