Nix represents its builds in a way that's similar: each "derivation" is a text file like /nix/store/XXXXXXX-foo.drv, where XXXXXX is a hash of that file's content. This way each file can reference any others by their path, and there can never be cycles (unless we brute-forced SHA256 to find a pair of files which contain each others hashes!). This uses of hashing requires the files to be immutable, but that's good for caching/validation/reuse/etc. anyway.

Note that Nix doesn't use a shell to execute things, it uses raw `exec` calls (each .drv file specifies the absolute path to an executable, a list of argument strings, and a set of environment variable strings). Though in practice, most .drv files specify a bash executable ;)