for str in zzz aaa; do for file in `find -regex “.*$str.*\.js”`; do if [ `wc -l < $file` -ge 5 ]; then head -n 5 $file | tail -n 1 | tr “\n” ‘+’; fi; done; echo; done

(-iname is wrong here, we need full paths. Needless to say, the task for me was the fifth line of *zzz*.js and of *aaa*.js.) It gave the output

2594+9005+3949+2058+8393+
2594+1249+8496+4728+

I then copy-pasted that to

$ echo $(((2594+9005+3949+2058+8393)*(2594+1249+8496+4728)))

and got 443724933, which was correct. My first try was wrong, because I was processing files with less than 4 lines (in that run it was the fourth line for me), despite their explicit hint. head happily returned less than four lines and tail got the last of those, despite it not being the fourth line. But with the added conditional it works fine.

People doing this with a real programming language aren’t doing it right, IMO.

It’s nice to see somebody else using F# for this problems

There’s another overloaded version of GetFiles that receives a SearchOption. Here you can specify to get files of subdirectories in the given directory.