46 lines
1.7 KiB
Plaintext
46 lines
1.7 KiB
Plaintext
'\"
|
|
'\" 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.
|
|
'\"
|
|
'\" SCCS: @(#) if.n 1.6 96/03/25 20:16:42
|
|
'\"
|
|
.so man.macros
|
|
.TH if n "" Tcl "Tcl Built-In Commands"
|
|
.BS
|
|
'\" Note: do not modify the .SH NAME line immediately below!
|
|
.SH NAME
|
|
if \- Execute scripts conditionally
|
|
.SH SYNOPSIS
|
|
\fBif \fIexpr1 \fR?\fBthen\fR? \fIbody1 \fBelseif \fIexpr2 \fR?\fBthen\fR? \fIbody2\fR \fBelseif\fR ... ?\fBelse\fR? ?\fIbodyN\fR?
|
|
.BE
|
|
|
|
.SH DESCRIPTION
|
|
.PP
|
|
The \fIif\fR command evaluates \fIexpr1\fR as an expression (in the
|
|
same way that \fBexpr\fR evaluates its argument). The value of the
|
|
expression must be a boolean
|
|
.VS
|
|
(a numeric value, where 0 is false and
|
|
anything is true, or a string value such as \fBtrue\fR or \fByes\fR
|
|
for true and \fBfalse\fR or \fBno\fR for false);
|
|
.VE
|
|
if it is true then \fIbody1\fR is executed by passing it to the
|
|
Tcl interpreter.
|
|
Otherwise \fIexpr2\fR is evaluated as an expression and if it is true
|
|
then \fBbody2\fR is executed, and so on.
|
|
If none of the expressions evaluates to true then \fIbodyN\fR is
|
|
executed.
|
|
The \fBthen\fR and \fBelse\fR arguments are optional
|
|
``noise words'' to make the command easier to read.
|
|
There may be any number of \fBelseif\fR clauses, including zero.
|
|
\fIBodyN\fR may also be omitted as long as \fBelse\fR is omitted too.
|
|
The return value from the command is the result of the body script
|
|
that was executed, or an empty string
|
|
if none of the expressions was non-zero and there was no \fIbodyN\fR.
|
|
|
|
.SH KEYWORDS
|
|
boolean, conditional, else, false, if, true
|