These directories contain all DOMjudge releases. Each release is
distributed as a gzipped source tarball, together with a detached
GPG signature and a MD5/SHA-checksum file. You can check the integrity
(and authenticity with GPG) of a downloaded release, e.g. by running

$ gpg domjudge-x.y.z.tar.gz.asc

or a variant of

$ sha256sum -c domjudge-x.y.z.tar.gz.sha256sum

Older DOMjudge releases include statically compiled versions of the
bash and dash shells. The source code for these can be found under
the sources sub-directory.