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