diff options
Diffstat (limited to 'doc/fcopy.n')
| -rw-r--r-- | doc/fcopy.n | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/doc/fcopy.n b/doc/fcopy.n index de74d3c..5cda3e3 100644 --- a/doc/fcopy.n +++ b/doc/fcopy.n @@ -5,7 +5,7 @@ '\" 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 1.6 2005/05/10 18:33:59 kennykb Exp $ +'\" RCS: @(#) $Id: fcopy.n,v 1.7 2006/11/15 09:23:01 dkf Exp $ '\" .so man.macros .TH fcopy n 8.0 Tcl "Tcl Built-In Commands" @@ -19,47 +19,47 @@ fcopy \- Copy data from one channel to another .SH DESCRIPTION .PP -The \fBfcopy\fP command copies data from one I/O channel, \fIinchan\fR to another I/O channel, \fIoutchan\fR. -The \fBfcopy\fP command leverages the buffering in the Tcl I/O system to +The \fBfcopy\fR command copies data from one I/O channel, \fIinchan\fR to another I/O channel, \fIoutchan\fR. +The \fBfcopy\fR command leverages the buffering in the Tcl I/O system to avoid extra copies and to avoid buffering too much data in main memory when copying large files to slow destinations like network sockets. .PP -The \fBfcopy\fP +The \fBfcopy\fR command transfers data from \fIinchan\fR until end of file -or \fIsize\fP bytes have been -transferred. If no \fB\-size\fP argument is given, +or \fIsize\fR bytes have been +transferred. If no \fB\-size\fR argument is given, then the copy goes until end of file. All the data read from \fIinchan\fR is copied to \fIoutchan\fR. -Without the \fB\-command\fP option, \fBfcopy\fP blocks until the copy is complete +Without the \fB\-command\fR option, \fBfcopy\fR blocks until the copy is complete and returns the number of bytes written to \fIoutchan\fR. .PP -The \fB\-command\fP argument makes \fBfcopy\fP work in the background. -In this case it returns immediately and the \fIcallback\fP is invoked +The \fB\-command\fR argument makes \fBfcopy\fR work in the background. +In this case it returns immediately and the \fIcallback\fR is invoked later when the copy completes. -The \fIcallback\fP is called with +The \fIcallback\fR is called with one or two additional arguments that indicates how many bytes were written to \fIoutchan\fR. If an error occurred during the background copy, the second argument is the error string associated with the error. With a background copy, it is not necessary to put \fIinchan\fR or \fIoutchan\fR into -non-blocking mode; the \fBfcopy\fP command takes care of that automatically. +non-blocking mode; the \fBfcopy\fR command takes care of that automatically. However, it is necessary to enter the event loop by using -the \fBvwait\fP command or by using Tk. +the \fBvwait\fR command or by using Tk. .PP You are not allowed to do other I/O operations with \fIinchan\fR or \fIoutchan\fR during a background fcopy. If either \fIinchan\fR or \fIoutchan\fR get closed while the copy is in progress, the current copy is stopped -and the command callback is \fInot\fP made. +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\fP handlers during a background +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\fP handler will get a "channel busy" error. +Any I/O attempted by a \fBfileevent\fR handler will get a "channel busy" error. .PP \fBFcopy\fR translates end-of-line sequences in \fIinchan\fR and \fIoutchan\fR according to the \fB\-translation\fR option @@ -69,8 +69,8 @@ See the manual entry for \fBfconfigure\fR for details on the 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\fP or -as the argument to the callback for an asynchronous \fBfcopy\fP. +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 |