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'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 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: read.n,v 1.5 2000/09/07 14:27:50 poenitz Exp $
'\"
.so man.macros
.TH read n 8.1 Tcl "Tcl Built-In Commands"
.BS
'\" Note: do not modify the .SH NAME line immediately below!
.SH NAME
read \- Read from a channel
.SH SYNOPSIS
\fBread \fR?\fB\-nonewline\fR? \fIchannelId\fR
.sp
\fBread \fIchannelId numChars\fR
.BE
.SH DESCRIPTION
.PP
In the first form, the \fBread\fR command reads all of the data from
\fIchannelId\fR up to the end of the file.
If the \fB\-nonewline\fR switch is specified then the last character
of the file is discarded if it is a newline.
.VS 8.1
In the second form, the extra argument specifies how many characters to
read. Exactly that many characters will be read and returned, unless
there are fewer than \fInumChars\fR left in the file; in this case
all the remaining characters are returned. If the channel is
configured to use a multi-byte encoding, then the number of characters
read may not be the same as the number of bytes read.
.PP
If \fIchannelId\fR is in nonblocking mode, the command may not read as
many characters as requested: once all available input has been read,
the command will return the data that is available rather than
blocking for more input. If the channel is configured to use a
multi-byte encoding, then there may actually be some bytes remaining
in the internal buffers that do not form a complete character. These
bytes will not be returned until a complete character is available or
end-of-file is reached.
.VE 8.1
The \fB\-nonewline\fR switch is ignored if the command returns
before reaching the end of the file.
.PP
\fBRead\fR translates end-of-line sequences in the input into
newline characters according to the \fB\-translation\fR option
for the channel.
See the \fBfconfigure\fR manual entry for a discussion on ways in
which \fBfconfigure\fR will alter input.
.SH "SEE ALSO"
file(n), eof(n), fblocked(n), fconfigure(n)
.SH KEYWORDS
blocking, channel, end of line, end of file, nonblocking, read, translation, encoding
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