.TH READ 2
.SH NAME
read, write \- read or write file
.SH SYNOPSIS
.B
long read(int fd, void *buf, long nbytes)
.PP
.B
long write(int fd, void *buf, long nbytes)
.SH DESCRIPTION
.I Read
reads
.I nbytes
bytes of data
from the offset in the file associated with
.I fd
into memory at
.IR buf .
The offset is advanced by the number of bytes read.
It is not guaranteed
that all
.I nbytes
bytes will be read; for example
if the file refers to the console, at most one line
will be returned.
In any event the number of characters read is returned.
A return value of
0 is conventionally interpreted as end of file.
.PP
.I Write
writes
.I nbytes
bytes of data starting at
.I buf
to the file associated with
.I fd
at the file offset.
The offset is advanced by the number of bytes written.
The number of characters actually written is returned.
It should be regarded as an error
if this is not the same as requested.
.SH SEE ALSO
.IR intro (2),
.IR open (2), 
.IR dup (2),
.IR pipe (2)
.SH DIAGNOSTICS
These functions set
.I errstr.