# phpman > man > NULL(4)

[NULL(4)](https://www.chedong.com/phpMan.php/man/NULL/4/markdown)                               Linux Programmer's Manual                              [NULL(4)](https://www.chedong.com/phpMan.php/man/NULL/4/markdown)



## NAME
       null, zero - data sink

## DESCRIPTION
       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)](https://www.chedong.com/phpMan.php/man/read/2/markdown) 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
       _/dev/null_
       _/dev/zero_

## NOTES
       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
       [**chown**(1)](https://www.chedong.com/phpMan.php/man/chown/1/markdown), [**mknod**(1)](https://www.chedong.com/phpMan.php/man/mknod/1/markdown), [**full**(4)](https://www.chedong.com/phpMan.php/man/full/4/markdown)

## COLOPHON
       This page is part of release 5.10 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)](https://www.chedong.com/phpMan.php/man/NULL/4/markdown)