Over time you accumulate cruft in Maven repos; maybe there are missing SHA1 files or POM files and you're getting stupid errors from Maven about bad checksums, etc. etc. Here are several simple scripts to regenerate all missing sha1 files as well as shell POM files (with enough information so Maven stops yelling at you).

To add missing sha1 files: Place add-missing-sha1-hashes.sh and make-sha1.sh in your Maven repository root directory, and make them executable. If you are on Mac OS X instead of Linux, you'll need to also add the sha1sum script and make sure it's on your path. You can add it to /usr/bin which is where it is in Linux. Then run add-missing-sha1-hashes.sh and voila!

To add missing POM files: Place the add-missing-poms.sh shell script and the make_poms.rb Ruby script in your Maven repository root directory. Make the shell script executable. Ruby should be on your path as well. Then run add-missing-poms.sh and voila!