NAME
       if - Execute scripts conditionally

SYNOPSIS
       if expr1 ?then? body1 elseif expr2 ?then? body2 elseif ...
       ?else? ?bodyN?


DESCRIPTION
       The if command evaluates expr1 as an  expression  (in  the
       same  way that expr evaluates its argument).  The value of
       the expression must be a boolean (a numeric value, where 0
       is  false  and anything is true, or a string value such as
       true or yes for true and false or no for false); if it  is
       true  then  body1  is  executed  by  passing it to the Tcl
       interpreter.   Otherwise  expr2   is   evaluated   as   an
       expression  and  if it is true then body2 is executed, and
       so on.  If none of the expressions evaluates to true  then
       bodyN  is  executed.   The  then  and  else  arguments are
       optional ``noise words'' to make  the  command  easier  to
       read.    There  may  be  any  number  of  elseif  clauses,
       including zero.  BodyN may also be omitted as long as else
       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 bodyN.


KEYWORDS
