sub checkLogin {

  my $loginName = shift;

  # Do not clobber open FH file handles
  local *FH;

  my $file = $SETTINGS{userfile};
  open FH, $file or die qq(Cannot open "$file": $!);
  flock FH, LOCK_EX if $^O ne 'MSWin32';

  while ( <FH> ) {
    my( $user, $password ) = ( split /\t/, $_ )[1, 2];
    if ( $user =~ m/^$loginName$/) {
      if ( $password =~ m/^$password$/) {
        return 'true';
      }
    }
  }
  close FH;
  return '';
}

Example 3: Eliminating a flag variable.