'\"
'\" 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 1.2 2003/11/24 05:09:59 bbbush Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
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'\"
'\" .AS ?type? ?name?
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'\" .BS
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'\"	Begin an indented unfilled display.
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'\"	End of indented unfilled display.
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'\" .SO
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'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
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'\" .UL arg1 arg2
'\"	Print arg1 underlined, then print arg2 normally.
'\"
'\" RCS: @(#) $Id: fcopy.n,v 1.2 2003/11/24 05:09:59 bbbush Exp $
'\"
'\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
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.nr ^l \n(.l
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.ie !"\\$4"" .TP \\$4
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\&\\$1	\\fI\\$2\\fP	(\\$3)
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\&\\$1	\\fI\\$2\\fP
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\&\\fI\\$1\\fP
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..
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.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
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..
.AS Tcl_Interp Tcl_CreateInterp in/out
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\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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See the \\fBoptions\\fR manual entry for details on the standard options.
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Command-Line Name:	\\fB\\$1\\fR
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\\$1\l'|0\(ul'\\$2
..
.TH fcopy 3tcl 8.0 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
fcopy \- 從一個通道向另一個複製數據
.SH "總覽 SYNOPSIS"
\fBfcopy \fIinchan\fR \fIoutchan\fR ?\fB\-size \fIsize\fR? ?\fB\-command \fIcallback\fR?
.BE

.SH "描述 DESCRIPTION"
.PP
\fBfcopy\fR  命令從一個 I/O 通道 \fIinchan\fR  向另一個 I/O 通道 \fIoutchan\fR  
複製數據。\fBfcopy\fR  命令在 Tcl I/O 系統中起到緩衝的槓桿作用(leverage)，它避免額外的複製，並且在向慢速目標如網絡套接口複製大文件的時候避免在主存中緩衝過多的數據。
.PP
 \fBfcopy\fR 命令從 \fIinchan\fR  傳輸數據直到文件結束或傳輸完 \fIsize\fR字節。如果沒有給出 \fB-size\fR 參數，則複製持續到文件結束。從 \fIinchan\fR讀的所有數據都複製到 \fIoutchan\fR。如果沒有 \fB-command\fR選項，在複製完成並返回寫到 \fIoutchan \fR的字節數之前 \fBfcopy\fR  將阻塞。
.PP
\fB-command\fR 參數使 \fBfcopy\fR在後臺工作。在這種情況下它立即返回，並在複製完成時調用  \fIcallback\fR。調用 \fIcallback\fR 加上一個或兩個額外的參數來指示有多少字節被寫到了 \fIoutchan\fR。在後臺複製期間如果發生了一個錯誤，第二個參數是與錯誤相關聯的錯誤字符串。使用後臺複製不需要把 \fIinchan\fR 或 \fIoutchan\fR 轉換成非阻塞模式；\fBfcopy\fR 命令將自動關照這些。但是，需要使用 \fBvwait\fR 命令或使用 Tk 進入事件循環。
.PP
在後臺複製期間不允許對 \fIinchan\fR 或 \fIoutchan \fR做其他 I/O 操作。如果在複製進行期間 \fIinchan\fR 或 \fIoutchan\fR  中被關閉，停止當前的複製並且不做命令回調。如果 \fIinchan\fR被關閉，則寫出爲 \fIoutchan\fR  而排隊(queue)的所有數據。
.PP
注意在一個命令複製期間 \fIinchan\fR 可以變成可讀的。在一個後臺複製期間你應該關閉任何 \fBfileevent\fR句柄，這樣這些句柄不與複製相觸及(interfere)。通過一個 \fBfileevent\fR句柄的任何 I/O 嘗試將得到一個 "channel busy"  錯誤。
.PP
.PP
\fBFcopy\fR  依據 \fIinchan\fR 和 \fIoutchan \fR的 \fB-translation\fR選項來轉換它們中的文件行結束序列。參見\fBfconfigure\fR的手冊條目來得到 \fB-translation\fR  選項的詳情。轉換意味着從 \fIinchan\fR 讀到的字節數與寫到 \fIoutchan\fR.的字節數可能不同。只報告寫到 \fIoutchan\fR中的字節數。要麼作爲同步的 \fBfcopy\fR 的返回值，要麼作爲給異步的 \fBfcopy \fR的回調的參數。  

.SH "範例 EXAMPLE"
.PP
第一個例子展示了回調如何得到傳遞給它的傳輸了的字節數。它還使用 vwait  來使應用進入事件循環。當然，不使用回調也能做出這個簡化了的例子。
.DS
proc Cleanup {in out bytes {error {}}} {
    global total
    set total $bytes
    close $in
    close $out
    if {[string length $error] != 0} {
	# error occurred during the copy
    }
}
set in [open $file1]
set out [socket $server $port]
fcopy $in $out -command [list Cleanup $in $out]
vwait total

.DE
.PP
第二個例子按塊(chunk)複製並在命令回調中測試文件結束。  
.DS
proc CopyMore {in out chunk bytes {error {}}} {
    global total done
    incr total $bytes
    if {([string length $error] != 0) || [eof $in] {
	set done $total
	close $in
	close $out
    } else {
	fcopy $in $out -command [list CopyMore $in $out $chunk] \\
	    -size $chunk
    }
}
set in [open $file1]
set out [socket $server $port]
set chunk 1024
set total 0
fcopy $in $out -command [list CopyMore $in $out $chunk] -size $chunk
vwait done

.DE

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

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

.SH "[中文版維護人]"
.B 寒蟬退士
.SH "[中文版最新更新]"
.B 2001/08/02
.SH "《中國 Linux 論壇 man 手冊頁翻譯計劃》:"
.BI http://cmpp.linuxforum.net
.SH "跋"
.br
本頁面中文版由中文 man 手冊頁計劃提供。
.br
中文 man 手冊頁計劃：\fBhttps://github.com/man-pages-zh/manpages-zh\fR