perl if elsif else

if ( $#ARGV < 0 ){
        print "请输入一个日期参数
";
        exit(-1);
    }
  $var = $ARGV[0];
print "$var is $var
";
if ($var =~/fred/) {
print "fred
";
}
elsif ($var =~/red/) {
print "red
";
}
else  {
print "black
";
}