'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1997 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: fcopy.n,v 1.13 2007/10/25 14:07:32 dkf Exp $
'\" RCS: @(#) $Id: fcopy.n,v 1.14 2007/10/26 20:11:52 dgp Exp $
'\" 
.so man.macros
.TH fcopy n 8.0 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
fcopy \- Copy data from one channel to another

and the command callback is \fInot\fR made.
If \fIinchan\fR is closed,
then all data already queued for \fIoutchan\fR is written out.
.PP
Note that \fIinchan\fR can become readable during a background copy.
You should turn off any \fBfileevent\fR handlers during a background
copy so those handlers do not interfere with the copy.
Any I/O attempted by a \fBfileevent\fR handler will get a
Any I/O attempted by a \fBfileevent\fR handler will get a "channel busy" error.
.QW "channel busy"
error.
.PP
\fBFcopy\fR translates end-of-line sequences in \fIinchan\fR and \fIoutchan\fR
according to the \fB\-translation\fR option
for these channels.
See the manual entry for \fBfconfigure\fR for details on the
\fB\-translation\fR option.
The translations mean that the number of bytes read from \fIinchan\fR
can be different than the number of bytes written to \fIoutchan\fR.
Only the number of bytes written to \fIoutchan\fR is reported,
either as the return value of a synchronous \fBfcopy\fR or
as the argument to the callback for an asynchronous \fBfcopy\fR.
.PP
\fBFcopy\fR obeys the encodings and character translations configured
for the channels. This
means that the incoming characters are converted internally first
UTF-8 and then into the encoding of the channel \fBfcopy\fR writes
to. See the manual entry for \fBfconfigure\fR for details on the
\fB\-encoding\fR and \fB\-translation\fR options. No conversion is
done if both channels are set to encoding
.QW "binary"
and have matching translations. If only the output channel is set to encoding
done if both channels are
set to encoding "binary" and have matching translations. If only the
output channel is set to
.QW "binary"
the system will write the internal UTF-8 representation of the incoming
characters. If only the input channel is set to encoding
.QW "binary"
the system will assume that the incoming bytes are valid UTF-8 characters and
convert them according to the output encoding. The behaviour of the system for
bytes which are not valid UTF-8 characters is undefined in this case.
encoding "binary" the system will write the internal UTF-8
representation of the incoming characters. If only the input channel
is set to encoding "binary" the system will assume that the incoming
bytes are valid UTF-8 characters and convert them according to the
output encoding. The behaviour of the system for bytes which are not
valid UTF-8 characters is undefined in this case.

.SH EXAMPLES
.PP
The first example transfers the contents of one channel exactly to
another. Note that when copying one file to another, it is better to
use \fBfile copy\fR which also copies file metadata (e.g. the file
access permissions) where possible.
.CS

set out [socket $server $port]
set chunk 1024
set total 0
\fBfcopy\fR $in $out -size $chunk \\
        -command [list CopyMore $in $out $chunk]
vwait done
.CE

.SH "SEE ALSO"
eof(n), fblocked(n), fconfigure(n), file(n)

.SH KEYWORDS
blocking, channel, end of line, end of file, nonblocking, read, translation