set x 1;

if {$x == 2} {puts "$x is 2"} else {puts "$x is not 2"}

if {$x != 1} {
  puts "$x is != 1"
  } else {
  puts "$x is 1
  }

if $x==1 {puts "GOT 1"}

;# Two passes of substitution will be done on this test string
;#  The initial pass replaces $y with x
;#  Within the if statement, $x is replaced with 1

set y x;
if "$$y != 1" {
  puts "$$y is != 1"
  } else {
  puts "$$y is 1"
  }