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+.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\"
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\" 
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date.  The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein.  The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\" 
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" License.
+.\" Modified Sat Jul 24 18:34:44 1993 by Rik Faith (faith@cs.unc.edu)
+.\" Merged readv.[23], 2002-10-17, aeb
+.\"
+.TH READV 2  2002-10-17 "" "Linux Programmer's Manual"
+.SH NAME
+readv, writev \- read or write data into multiple buffers
+.SH SYNOPSIS
+.nf
+.B #include <sys/uio.h>
+.sp
+.BI "ssize_t readv(int " fd ", const struct iovec *" vector ", int " count );
+.sp
+.BI "ssize_t writev(int " fd ", const struct iovec *" vector ", int " count );
+.fi
+.SH DESCRIPTION
+The
+.B readv()
+function reads
+.I count
+blocks from the file associated with the file descriptor
+.I fd
+into the multiple buffers described by
+.IR vector .
+.PP
+The
+.B writev()
+function writes at most
+.I count
+blocks described by
+.I vector
+to the file associated with the file descriptor
+.IR fd .
+.PP
+The pointer
+.I vector
+points to a
+.B struct iovec
+defined in
+.B <sys/uio.h>
+as
+.PP
+.br
+.nf
+.in 10
+struct iovec {
+.in 14
+void *iov_base;   /* Starting address */
+size_t iov_len;   /* Number of bytes */
+.in 10
+};
+.fi
+.PP
+Buffers are processed in the order specified.
+.PP
+The
+.B readv()
+function works just like
+.BR read (2)
+except that multiple buffers are filled.
+.PP
+The
+.B writev()
+function works just like
+.BR write (2)
+except that multiple buffers are written out.
+.PP
+.SH "RETURN VALUE"
+On success, the
+.B readv()
+function returns the number of bytes read; the
+.B writev()
+function returns the number of bytes written.
+On error, \-1 is returned, and \fIerrno\fP is set appropriately.
+.SH ERRORS
+The errors are as given for
+.BR read (2)
+and
+.BR write (2).
+Additionally the following error is defined.
+.TP
+.B EINVAL
+The sum of the
+.I iov_len
+values overflows an
+.B ssize_t
+value. Or,
+the vector count \fIcount\fR is zero or greater than \fBMAX_IOVEC\fR.
+.SH "CONFORMING TO"
+4.4BSD (the
+.B readv
+and
+.B writev
+functions first appeared in BSD 4.2), Unix98, POSIX 1003.1-2001.
+Linux libc5 used \fBsize_t\fR as the type of the \fIcount\fR parameter,
+and \fBint\fP as return type for these functions.
+.\" The readv/writev system calls were buggy before Linux 1.3.40.
+.\" (Says release.libc.)
+.SH BUGS
+It is not advisable to mix calls to functions like
+.B readv()
+or
+.BR writev() ,
+which operate on file descriptors, with the functions from the stdio
+library; the results will be undefined and probably not what you want.
+.SH "SEE ALSO"
+.BR read (2),
+.BR write (2)