Two Three tools for extracting information and/or manipulating large pgn files. Especially pgn-extract did impress me. From lichess I downloaded a file (213 GB!) for later training a NN. It took close to 12h on a single CPU but I was able to extract around 5 GB of games, filtering time control between 900 and 3600 seconds plus dividing the files into the ECO codes A – E.

(Update:) Someone asked for the uci-analyser, here you go:

Binary: analyse
Source/help: https://www.cs.kent.ac.uk/people/staff/djb/uci-analyser/

Binary: pgn-extract
Source: https://github.com/MichaelB7/pgn-extract
Help: https://www.cs.kent.ac.uk/people/staff/djb/pgn-extract/help.html

Binary: scoutfish-20170211 (x86-64, I wasn’t able yet to compile an arm64 binary)
Source: https://github.com/mcostalba/scoutfish