How to Test if Git Repository is Shallow?

Question

When I make a local clone from a repository, the clone fails if the origin repository is shallow.

git clone -l -- . target-dir

As that is not always the case I'd like to find out prior clone but don't know how to do that.

What I tried so far is very little, basically creating error messages on clone. At the moment I just fetch to unshallow and if that fails, I do a plain fetch because if the repo would be shallow, it should be unshallow afterwards:

if ! git fetch --unshallow; then
    git fetch
fi

However there is no guarantee for being unshallow afterwards (remote to fetch from can be shallow, too), so a test for the (un)shallowness of a git repository would be much better.

Answer 1

If your Git is 2.15 or later, run:

git rev-parse --is-shallow-repository 

which will print false (not shallow) or true (shallow):

if $(git rev-parse --is-shallow-repository); then     ... repository is shallow ... fi 

The answer below dates back to Git versions before 2.15.

---

If your Git is older than 2.15,¹ just test for the file shallow in the Git repository directory:²

if [ -f "$(git rev-parse --git-dir)"/shallow ]; then     echo this is a shallow repository; else     echo not a shallow repository; fi 

or (shorter):

[ -f "$(git rev-parse --git-dir)"/shallow ] && echo true || echo false 

You can turn this into a shell function:

test_shallow() {     [ -f "$(git rev-parse --git-dir)"/shallow ] && echo true || echo false } 

and even automate the Git version checking:

test_shallow() {     set -- $(git rev-parse --is-shallow-repository)     if [ x$1 == x--is-shallow-repository ]; then         [ -f "$(git rev-parse --git-dir)"/shallow ] && set true || set false     fi     echo $1 } 

---

¹git --version will print the current version number:

$ git --version 2.14.1  $ git --version git version 2.7.4 

etc. (I have multiple versions on different VMs/machines at this point.) You can also run:

git rev-parse --is-shallow-repository 

If it just prints --is-shallow-repository, your Git is pre-2.15 and lacks the option.

²To see why there are double quotes around $(git rev-parse --git-dir), see Tom Hale's comment. Note that testing this is a bit tricky since git rev-parse --git-dir from the top level of, e.g., the repository /tmp/with space just prints .git; you must be in a subdirectory, such as /tmp/with space/sub to observe the problem.

Answer 2

When you don't have access to the remote repository (not the case here, but still a possible scenario), a git clone is still a good way to test if that remote repository is shallow or not.

The problem is not transfer/create file needlessly when the clone would ultimately fail because of the shallow nature of said remote repository.

This is now fixed with Git 2.32 (Q2 2021): "git clone"^(man) new --reject-shallow option fails the clone as soon as we notice that we are cloning from a shallow repository.

See commit 4fe788b (01 Apr 2021) by Li Linchao (Cactusinhand).
^{(Merged by Junio C Hamano -- gitster -- in commit 22eee7f, 08 Apr 2021)}

builtin/clone.c: add --reject-shallow option

^{Signed-off-by: Li Linchao}

In some scenarios, users may want more history than the repository offered for cloning, which happens to be a shallow repository, can give them.
But because users don't know it is a shallow repository until they download it to local, we may want to refuse to clone this kind of repository, without creating any unnecessary files.

The '--depth=x' option cannot be used as a solution; the source may be deep enough to give us 'x' commits when cloned, but the user may later need to deepen the history to arbitrary depth.

Teach '--reject-shallow' option to "git clone"^(man) to abort as soon as we find out that we are cloning from a shallow repository.

No local file created!

The error message will be (with the test clone command):

git -c clone.rejectshallow=true clone --no-local shallow-repo source repository is shallow, reject to clone. 

git config now includes in its man page:

clone.rejectShallow

Reject to clone a repository if it is a shallow one, can be overridden by passing option --reject-shallow in command line.

git clone now includes in its man page:

--[no-]reject-shallow

Fail if the source repository is a shallow repository.
The 'clone.rejectShallow' configuration variable can be used to specify the default.