ironchest | Iron Chest minecraft | Video Game library

Reading / Writing the entire file every time you add a new block seems a bit messy, specially if you consider that you might restart the turtle in the process of writing the new file and end up with half your data being lost.

You do have a file system, so why not use that instead? Create a directory and write a new file for every block name, then save the coordinates in it. This also allows you to store more than one chest for each block-type, in case you get filthy rich happens sooner than you'd expect when using turtles to excavate huge chunks of the map.

I just realized that I didn't actually answer the question, so here goes that:

When you have a file file, you can easily read a single line with file.readLine(). This returns either the line it read as a string, or nil if you're at the end of a file. Assuming you just write three coordinates separated by spaces after the block name, you can then parse them into a table like this: