Filtering lines efficiently

Whenever you are dealing with log lines or that you're program is filtering data you always have to handle 'escaping' efficiently.

While developing a log module using a gen_event, I needed to escape simple quotes.
Sometime thoses quotes were already escaped...

I've found this regexp to handle gracefully the case:

re:replace( Bin, "(?<!\\\\)'", "\\\\'", [ global ] ).

Reading an openssl .priv.key file and extracting the key

Extracting the private key from a .priv.key file is simple.
The private key is encrypted using a AES-128 with your passphrase.

The initial vector is also stored in the file, you can extract it directly from the first line:

get_salt( <<"Salted__", Salt:8/binary, Rest/binary>> ) ->
        {Salt, Rest}.