Currently, there's no way to selectively consider cabal files for init. I think it makes sense to have it take a list of sub-directories to search in, defaulting to .. This'd be consistent with stack build taking a list of sub-directories and building all projects in those sub-directories.

The --ignore-subdirs flag would still work - it'd mean that cabal files in sub-directories of the specified dirs are ignored.

I'd hope that this would work with bash expansion, so that if you do stack init --ignore-subdirs *, it'd build all the packages that are immediate subdirs (to faciliate this, merely warn when a path to a file is specified).