Tag a commit:

$ git tag 0.1

$ git tag

0.1

Delete a tag:

$ git tag -d 0.1

Get the latest commit hash:

$ git rev-list --tags --max-count=1

94c5715694c5715687a962008dd71191460fc4e32370425a

Get any tag on a commit:

$ git describe --tags 94c5715

0.1