tell.n

tcl是工具命令语言

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'\" RCS: @(#) $Id: tell.n,v 1.5 2001/09/14 19:20:40 andreas_kupries Exp $
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.so man.macros
.TH tell n 8.1 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
tell \- Return current access position for an open channel
.SH SYNOPSIS
\fBtell \fIchannelId\fR
.BE

.SH DESCRIPTION
.PP
.VS 8.1
Returns an integer string giving the current access position in
\fIchannelId\fR.  This value returned is a byte offset that can be passed to
\fBseek\fR in order to set the channel to a particular position.  Note
that this value is in terms of bytes, not characters like \fBread\fR.
.VE 8.1
The value returned is -1 for channels that do not support
seeking.
.PP
.VS
\fIChannelId\fR must be an identifier for an open channel such as a
Tcl standard channel (\fBstdin\fR, \fBstdout\fR, or \fBstderr\fR),
the return value from an invocation of \fBopen\fR or \fBsocket\fR, or
the result of a channel creation command provided by a Tcl extension.
.VE

.SH "SEE ALSO"
file(n), open(n), close(n), gets(n), seek(n), Tcl_StandardChannels(3)

.SH KEYWORDS
access position, channel, seeking