Comment by diggan

This the latest edition I know about being online somewhere: https://archive.org/details/pil-4th (Programming In Lua - Fourth edition, for Lua 5.3, 2016)

I'm not sure there is a fifth edition (for Lua 5.4) but the manual/reference + fourth edition seems good enough for at least my usage: https://www.lua.org/manual/5.4/manual.html