null (4)

Leading comments

Copyright (c) 1993 Michael Haardt (michael@moria.de),
    Fri Apr  2 11:32:09 MET DST 1993

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(The comments found at the beginning of the groff file "man4/null.4".)

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) returns 0), whereas reads from /dev/zero always return bytes containing zero (aq\0aq 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), mknod(1), full(4)

COLOPHON

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