$varalias =~ s/=.*//;  # Delete everything(.*) from the equals on
$vartarget =~ s/"$//;  # Delete the quote at the end($)

##</code><code>##

# If able to delete the stuff(.*) between the beginning
# of the line(^) and the word 'alias' and one-or-more spaces(\s+)
# found after that ...
if (s/^.*?alias\s+//)
{
     # Extract the 1st, 5th and 7th "words"
     my ($varalias, $varsource, $vartarget)
           = (split(' '))[1,5,7];

     # Then whatever...
}

##</code><code>##

print OUT <<END_HTML;
<FOO>
<FOO>$varsource
<FOO>
<FOO>$vartarget
<FOO>
<FOO>
END_HTML

##</code><code>##

if ($something)
{
      some_code();

      if ($something_else)
      {
             some_other_code();
      }
}