Question

I have the following tree:

O---O---O---O <- master
 \--O---O <- work branch
        /\
        ||
        TAG

When I run git cat-file I get an error:

> git cat-file tag TAG
fatal: git cat-file TAG: bad file

Do anyone has an idea what is wrong here?

Answer 1

What do you expect to happen? Perhaps you want:

git cat-file commit TAG

… which prints some information about the commit that TAG points to. (i.e. the <type> that git cat-file is expecting should be commit rather than tag.)

Update: as I mentioned in a comment below, if what you want is the object name (the hash) of the commit, you can get that with:

git rev-parse --verify TAG