72 lines
2.5 KiB
Plaintext
72 lines
2.5 KiB
Plaintext
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'\"
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'\" Copyright (c) 1993 The Regents of the University of California.
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'\" Copyright (c) 1994-1996 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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.TH gets n 7.5 Tcl "Tcl Built-In Commands"
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.so man.macros
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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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gets \- Read a line from a channel
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.SH SYNOPSIS
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\fBgets \fIchannelId\fR ?\fIvarName\fR?
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.BE
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.SH DESCRIPTION
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.PP
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This command reads the next line from \fIchannelId\fR, returns everything
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in the line up to (but not including) the end-of-line character(s), and
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discards the end-of-line character(s).
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.PP
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\fIChannelId\fR must be an identifier for an open channel such as the
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Tcl standard input channel (\fBstdin\fR), the return value from an
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invocation of \fBopen\fR or \fBsocket\fR, or the result of a channel
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creation command provided by a Tcl extension. The channel must have
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been opened for input.
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.PP
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If \fIvarName\fR is omitted the line is returned as the result of the
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command.
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If \fIvarName\fR is specified then the line is placed in the variable by
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that name and the return value is a count of the number of characters
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returned.
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.PP
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If end of file occurs while scanning for an end of
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line, the command returns whatever input is available up to the end of file.
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If \fIchannelId\fR is in non-blocking mode and there is not a full
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line of input available, the command returns an empty string and
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does not consume any input.
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If \fIvarName\fR is specified and an empty string is returned in
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\fIvarName\fR because of end-of-file or because of insufficient
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data in non-blocking mode, then the return count is -1.
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Note that if \fIvarName\fR is not specified then the end-of-file
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and no-full-line-available cases can
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produce the same results as if there were an input line consisting
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only of the end-of-line character(s).
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The \fBeof\fR and \fBfblocked\fR commands can be used to distinguish
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these three cases.
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.SH "EXAMPLE"
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This example reads a file one line at a time and prints it out with
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the current line number attached to the start of each line.
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.PP
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.CS
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set chan [open "some.file.txt"]
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set lineNumber 0
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while {[\fBgets\fR $chan line] >= 0} {
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puts "[incr lineNumber]: $line"
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}
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close $chan
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.CE
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.SH "SEE ALSO"
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file(n), eof(n), fblocked(n), Tcl_StandardChannels(3)
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.SH KEYWORDS
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blocking, channel, end of file, end of line, line, non-blocking, read
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'\" Local Variables:
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'\" mode: nroff
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'\" fill-column: 78
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'\" End:
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