This simple shell script will scrape all ID's from movies within an IMDb-List (filtered, no user lists) into a textfile
Example for a List-URL:
https://www.imdb.com/search/title/?genres=thriller&explore=title_type,genres&title_type=movie&ref_=adv_explore_rhs
Userlists like https://www.imdb.com/list/ls01239352349/ are coming soon.
You probably need to install lynx. Everything else should already be pre-installed on your linux machine.
For Ubuntu: sudo apt install lynx