179 lines
7.7 KiB
Plaintext
179 lines
7.7 KiB
Plaintext
'\"
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'\" Copyright (c) 1995-1996 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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'\" SCCS: @(#) fconfigure.n 1.23 96/04/16 08:20:07
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'\"
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.so man.macros
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.TH fconfigure n 7.5 Tcl "Tcl Built-In Commands"
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.BS
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'\" Note: do not modify the .SH NAME line immediately below!
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.SH NAME
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fconfigure \- Set and get options on a channel
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.SH SYNOPSIS
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.nf
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\fBfconfigure \fIchannelId\fR
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\fBfconfigure \fIchannelId\fR \fIname\fR
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\fBfconfigure \fIchannelId\fR \fIname value \fR?\fIname value ...\fR?
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.fi
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.BE
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.SH DESCRIPTION
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.PP
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The \fBfconfigure\fR command sets and retrieves options for channels.
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\fIChannelId\fR identifies the channel for which to set or query an option.
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If no \fIname\fR or \fIvalue\fR arguments are supplied, the command
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returns a list containing alternating option names and values for the channel.
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If \fIname\fR is supplied but no \fIvalue\fR then the command returns
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the current value of the given option.
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If one or more pairs of \fIname\fR and \fIvalue\fR are supplied, the
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command sets each of the named options to the corresponding \fIvalue\fR;
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in this case the return value is an empty string.
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.PP
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The options described below are supported for all channels. In addition,
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each channel type may add options that only it supports. See the manual
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entry for the command that creates each type of channels for the options
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that that specific type of channel supports. For example, see the manual
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entry for the \fBsocket\fR command for its additional options.
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.TP
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\fB\-blocking\fR \fIboolean\fR
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The \fB\-blocking\fR option determines whether I/O operations on the
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channel can cause the process to block indefinitely.
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The value of the option must be a proper boolean value.
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Channels are normally in blocking mode; if a channel is placed into
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nonblocking mode it will affect the operation of the \fBgets\fR,
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\fBread\fR, \fBputs\fR, \fBflush\fR, and \fBclose\fR commands;
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see the documentation for those commands for details.
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For nonblocking mode to work correctly, the application must be
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using the Tcl event loop (e.g. by calling \fBTcl_DoOneEvent\fR or
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invoking the \fBvwait\fR command).
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.TP
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\fB\-buffering\fR \fInewValue\fR
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If \fInewValue\fR is \fBfull\fR then the I/O system will buffer output
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until its internal buffer is full or until the \fBflush\fR command is
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invoked. If \fInewValue\fR is \fBline\fR, then the I/O system will
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automatically flush output for the channel whenever a newline character
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is output. If \fInewValue\fR is \fBnone\fR, the I/O system will flush
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automatically after every output operation.
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The default is for \fB\-buffering\fR to be set to \fBfull\fR except for
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channels that connect to terminal-like devices; for these channels the
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initial setting is \fBline\fR.
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.TP
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\fB\-buffersize\fR \fInewSize\fR
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\fINewvalue\fR must be an integer; its value is used to set the size of
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buffers, in bytes, subsequently allocated for this channel to store input
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or output. \fINewvalue\fR must be between ten and one million, allowing
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buffers of ten to one million bytes in size.
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.TP
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\fB\-eofchar\fR \fIchar\fR
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.TP
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\fB\-eofchar\fR \fB{\fIinChar outChar\fB}\fR
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This option supports DOS file systems that use Control-z (\ex1a) as
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an end of file marker.
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If \fIchar\fR is not an empty string, then this character signals
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end of file when it is encountered during input.
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For output, the end of file character is output when
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the channel is closed.
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If \fIchar\fR is the empty string, then there is no special
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end of file character marker.
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For read-write channels, a two-element list specifies
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the end of file marker for input and output, respectively.
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As a convenience, when setting the end-of-file character
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for a read-write channel
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you can specify a single value that will apply to both reading and writing.
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When querying the end-of-file character of a read-write channel,
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a two-element list will always be returned.
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The default value for \fB\-eofchar\fR is the empty string in all
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cases except for files under Windows. In that case the \fB\-eofchar\fR
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is Control-z (\ex1a) for reading and the empty string for writing.
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.TP
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\fB\-translation\fR \fImode\fR
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.TP
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\fB\-translation\fR \fB{\fIinMode outMode\fB}\fR
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In Tcl scripts the end of a line is always represented using a
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single newline character (\en).
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However, in actual files and devices the end of a line may be
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represented differently on different platforms, or even for
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different devices on the same platform. For example, under UNIX
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newlines are used in files, whereas carriage-return-linefeed
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sequences are normally used in network connections.
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On input (i.e., with \fBgets\fP and \fBread\fP)
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the Tcl I/O system automatically translates the external end-of-line
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representation into newline characters.
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Upon output (i.e., with \fBputs\fP),
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the I/O system translates newlines to the external
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end-of-line representation.
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The default translation mode, \fBauto\fP, handles all the common
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cases automatically, but the \fB\-translation\fR option provides
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explicit control over the end of line translations.
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.RS
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.PP
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The value associated with \fB\-translation\fR is a single item for
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read-only and write-only channels.
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The value is a two-element list for read-write channels;
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the read translation mode is the first element of the list,
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and the write translation mode is the second element.
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As a convenience, when setting the translation mode for a read-write channel
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you can specify a single value that will apply to both reading and writing.
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When querying the translation mode of a read-write channel,
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a two-element list will always be returned.
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The following values are currently supported:
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.TP
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\fBauto\fR
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As the input translation mode, \fBauto\fR treats any of newline (\fBlf\fP),
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carriage return (\fBcr\fP), or carriage return followed by a newline (\fBcrlf\fP)
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as the end of line representation. The end of line representation can
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even change from line-to-line, and all cases are translated to a newline.
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As the output translation mode, \fBauto\fR chooses a platform specific
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representation; for sockets on all platforms Tcl
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chooses \fBcrlf\fR, for all Unix flavors, it chooses \fBlf\fR, for the
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Macintosh platform it chooses \fBcr\fR and for the various flavors of
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Windows it chooses \fBcrlf\fR.
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The default setting for \fB\-translation\fR is \fBauto\fR for both
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input and output.
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.TP
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\fBbinary\fR
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No end-of-line translations are performed. This is nearly identical to
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\fBlf\fP mode, except that in addition \fBbinary\fP mode also sets the
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end of file character to the empty string, which disables it.
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See the description of
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\fB\-eofchar\fP for more information.
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.TP
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\fBcr\fR
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The end of a line in the underlying file or device is represented
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by a single carriage return character.
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As the input translation mode, \fBcr\fP mode converts carriage returns
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to newline characters.
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As the output translation mode, \fBcr\fP mode
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translates newline characters to carriage returns.
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This mode is typically used on Macintosh platforms.
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.TP
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\fBcrlf\fR
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The end of a line in the underlying file or device is represented
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by a carriage return character followed by a linefeed character.
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As the input translation mode, \fBcrlf\fP mode converts
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carriage-return-linefeed sequences
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to newline characters.
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As the output translation mode, \fBcrlf\fP mode
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translates newline characters to
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carriage-return-linefeed sequences.
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This mode is typically used on Windows platforms and for network
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connections.
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.TP
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\fBlf\fR
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The end of a line in the underlying file or device is represented
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by a single newline (linefeed) character.
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In this mode no translations occur during either input or output.
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This mode is typically used on UNIX platforms.
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.RE
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.PP
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.SH "SEE ALSO"
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close(n), flush(n), gets(n), puts(n), read(n), socket(n)
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.SH KEYWORDS
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blocking, buffering, carriage return, end of line, flushing, linemode,
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newline, nonblocking, platform, translation
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