A regular expression line\d+= won't match with a text "blah1,blah1,blah1=".

You must adjust your regular expression, so it can match your 'blah...' string.

Please see perlretut, perlrequick and perlre for more information about regular expressions.

And you must print to your output handle, if you want the result in value.txt. Currently you are printing to STDOUT; see print