59 lines
2.5 KiB
Plaintext
59 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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'\" All rights reserved.
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'\"
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'\" Permission is hereby granted, without written agreement and without
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'\" license or royalty fees, to use, copy, modify, and distribute this
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'\" documentation for any purpose, provided that the above copyright
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'\" notice and the following two paragraphs appear in all copies.
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'\"
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'\" IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
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'\" FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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'\" ARISING OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
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'\" CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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'\"
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'\" THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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'\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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'\" AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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'\" ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
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'\" PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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'\"
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'\" $Header: /user6/ouster/tcl/man/RCS/if.n,v 1.1 93/05/03 17:34:01 ouster Exp $ SPRITE (Berkeley)
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'\"
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.so man.macros
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.HS if tcl
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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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if \- Execute scripts conditionally
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.SH SYNOPSIS
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\fBif \fIexpr1 \fR?\fBthen\fR? \fIbody1 \fBelseif \fIexpr2 \fR?\fBthen\fR? \fIbody2\fR \fBelseif\fR ... \fR?\fBelse\fR? ?\fIbodyN\fR?
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.BE
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.SH DESCRIPTION
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.PP
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The \fIif\fR command evaluates \fIexpr1\fR as an expression (in the
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same way that \fBexpr\fR evaluates its argument). The value of the
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expression must be a boolean
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.VS
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(a numeric value, where 0 is false and
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anything is true, or a string value such as \fBtrue\fR or \fByes\fR
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for true and \fBfalse\fR or \fBno\fR for false);
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.VE
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if it is true then \fIbody1\fR is executed by passing it to the
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Tcl interpreter.
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Otherwise \fIexpr2\fR is evaluated as an expression and if it is true
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then \fBbody2\fR is executed, and so on.
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If none of the expressions evaluates to true then \fIbodyN\fR is
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executed.
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The \fBthen\fR and \fBelse\fR arguments are optional
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``noise words'' to make the command easier to read.
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There may be any number of \fBelseif\fR clauses, including zero.
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\fIBodyN\fR may also be omitted as long as \fBelse\fR is omitted too.
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The return value from the command is the result of the body script
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that was executed, or an empty string
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if none of the expressions was non-zero and there was no \fIbodyN\fR.
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.SH KEYWORDS
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boolean, conditional, else, false, if, true
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