Research V3 release

[unix-history] / man / man2 / read.2

.pa 1
.he 'READ (II)'3/15/72'READ (II)'
.ti 0
NAME            read  --  read from file
.sp
.ti 0
SYNOPSIS        (file descriptor in r0)
.br
sys read; buffer; nbytes  / read = 3.
.br
(nread in r0)
.sp
.ti 0
DESCRIPTION     A file descriptor is a word
returned from a successful open\b\b\b\b____ or creat\b\b\b\b\b_____ call.
.sp
Buffer\b\b\b\b\b\b______ is the location of nbytes\b\b\b\b\b\b______ contiguous
bytes into which the input will be placed.  It is not guaranteed
that all nbytes\b\b\b\b\b\b______ bytes will be read; for example
if the file refers to a typewriter at most one line
will be returned.
In any event the number of characters read is returned
in r0.
.sp
If r0 returns with value 0, then
end-of-file has been reached.
.sp
.ti 0
SEE ALSO        open(II), creat(II)
.sp
.ti 0
DIAGNOSTICS     As mentioned,
r0 is 0 on return when the end of the file has been reached.
If the read was other\ 6wise unsuccessful
the error bit (c-bit) is set.  Many conditions,
can generate an error:
physical I/O errors, bad buffer address,
preposterous nbytes\b\b\b\b\b\b______, file descriptor not that of
an input file.
.sp
.ti 0
BUGS            --