.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved. The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\" @(#)read.2 6.1 (Berkeley) %G%
read, readv \- read input
cc = read(d, buf, nbytes)
cc = readv(d, iov, iovcnt)
of data from the object referenced by the descriptor
into the buffer pointed to by
performs the same action, but scatters the input data
buffers specified by the members of the
array: iov[0], iov[1], ..., iov[iovcnt\|\-\|1].
entry specifies the base address and length of an area
in memory where data should be placed.
will always fill an area completely before proceeding
On objects capable of seeking, the
given by the pointer associated with
the pointer is incremented by the number of bytes actually read.
Objects that are not capable of seeking always read from the current
position. The value of the pointer associated with such a
Upon successful completion,
return the number of bytes actually read and placed in the buffer.
The system guarantees to read the number of bytes requested if
the descriptor references a file which has that many bytes left
before the end-of-file, but in no other cases.
If the returned value is 0, then
end-of-file has been reached.
number of bytes actually read is returned.
Otherwise, a \-1 is returned and the global variable
is set to indicate the error.
will fail if one or more of the following are true:
\fID\fP is not a valid file or socket descriptor open for reading.
\fIBuf\fP points outside the allocated address space.
A read from a slow device was interrupted before
any data arrived by the delivery of a signal.
may return one of the following errors:
was less than or equal to 0, or greater than 16.
array overflowed a 32-bit integer.
dup(2), open(2), pipe(2), socket(2), socketpair(2)