DESCRIPTION
/dev/zero
is a zero special file.
Reads from a zero special file always return characters whose
value is "0" (\0 characters).
Data written on a zero special file is discarded or ignored.
Seeks on a zero special file always succeed.
Private
mmap()
of a zero special file is allowed (see
mmap(2)).
Shared
mmap()
is allowed but the memory region can be shared only with
descendants of the current process.
The
mmap()
of
/dev/zero
is special in that it behaves as a
MAP_ANONYMOUS
object.
Mapping
/dev/zero
gives the calling program a block of zero-filled
virtual memory of the size specified in the call to
mmap().
EXAMPLES
In the following example, the buffer "buf" is filled with "len" \0 characters.
fildes = open("/dev/zero",...)
read(fildes, buf, len)
In the following example, the process now has a range of "len" \0
characters at memory location "address":
fildes = open("/dev/zero",...)
address = mmap(0, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fildes,
any_offset)
