CODEWITHSUNDEEP
git
Raviraj
Raviraj

Reputation: 21

GIT checkout tag points to wrong sha1

I have a repository HELPER and about 350 tags created on it. I am on 'master' branch and want to checkout a tag for read-only purpose.

When i do checkout, it says it is pointing to some sha1 id which not the sha1 of that tag.

here is the snippet,

bash-4.1$ git checkout **HELPER_F62.3.REL**

HEAD is now at **7e04dfb**... *HELPER_OS4.1.35*

bash-4.1$ git show-ref **HELPER_F62.3.REL**

**d722076d24ec9d13d845094181f47801ca77b4ca** refs/tags/HELPER_F62.3.REL

bash-4.1$ git show-ref HELPER_OS4.1.35

2782a48d2044b0fc0aa60ecf2823967a2312e1dd refs/tags/HELPER_OS4.1.35

I do not want to create a new branch, and I am fine with the detached HEAD as i use this repo as a read-only repo.

Currently on git version 1.8.0-rc0

Upvotes: 1

Views: 724

Answers (1)

torek
torek

Reputation: 489638

I suspect you have an annotated tag. When you use git checkout to detach HEAD and get on the corresponding commit, you see the commit-ID rather than the annotated tag's ID.

You can see this with, e.g., git show-ref --deref:

$ git show-ref --deref master annotag
a430f6d91b98d382b8d96f6812fc2056a6e6f678 refs/heads/master
20e14672ee2253d38c1001179d8f17688d47059c refs/tags/annotag
a430f6d91b98d382b8d96f6812fc2056a6e6f678 refs/tags/annotag^{}

shows that branch master (which I tagged with git tag -a annotag to create an annotated tag) is where annotag resolves once de-referenced, even though annotag points to a separate git object.

(Lightweight tags point directly at commits, and are unchanged under --deref.)

Dealing with tags in shell scripts

If you just want to get the annotated tag's hash ID, or just want to get the target of the tag, use git rev-parse, like this:

$ git rev-parse annotag
2e79bc84c11eda5d73add5a9dfc6bf03c50c432d
$ git rev-parse annotag^{}
676699a0e0cdfd97521f3524c763222f1c30a094

Note that the ^{} suffix means follow the tag to whatever object it locates. If the tag locates a tree or blob object, rather than a commit, the hash ID you get from the above is that of the tree or blob. If you want to be sure that it is a commit, use the ^{commit} suffix notation:

$ git rev-parse annotag^{commit}
676699a0e0cdfd97521f3524c763222f1c30a094

If the commit points to some other kind of object than the one specified in the braces, you get an error:

$ git rev-parse annotag^{tag}
2e79bc84c11eda5d73add5a9dfc6bf03c50c432d
$ git rev-parse annotag^{blob}
error: annotag^{blob}: expected blob type, but the object dereferences to tree type
[more error messages, snipped]

These syntaxes (syntaces? syntagma?) are described in the gitrevisions documentation (q.v.).

Upvotes: 2

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