Validate if commit exists

Question

How to validate whether the commit with given sha exists in current branch?

There are many ways to parse outputs, but I need optimal way which returns boolean (for usage in bash script).

e.g.

sha=$1
if [ -z `git magic --validate $sha` ]; then
  echo "Invalid commit sha: $sha"
  exit 1
fi

Answer 1

git rev-parse --quiet --verify <commit>

Does not actually verify that commit (I guess SHA1 is what is meant) exists. It verifies that there is an object in the database corresponding to the SHA1 provided. That is, if there is a blob or tree object that matches the SHA1, it will report that it exists, even if it is not a commit.

git rev-parse --quiet --verify <sha1>^{commit}

This will verify that the object exists and that it is an object that can be used as a commit (commit or annotated tag).

Answer 2

The rev-list | grep method works fine; there's the tiniest bit of overhead because git has to print out all the SHA1s for grep to see, but it's not really a big deal.

You can also do it with git merge-base if you like - if the merge base of the target commit and the branch is the target commit, the branch contains the target commit:

if [ "$(git merge-base $commit $branch)" = "$commit" ]; then
    ...
fi

Either way you do it, note that rev-list and merge-base are going to be printing out SHA1s, so if the commit you're testing for inclusion is named by a branch or tag, you'll want to use git rev-parse to turn it into an SHA1 first.