null man page

null, zero — data sink


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




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)

Referenced By

dmsetup(8), full(4), gsisshd_config(5), sshd_config(5).

Explore man page connections for null(4).

zero(4) is an alias of null(4).