[git] Is it possible to cherry-pick a commit from another git repository?

I'm working with a git repository that needs a commit from another git repository that knows nothing of the first.

Typically I would cherry-pick using the HEAD@{x} in the reflog, but because this .git knows nothing of this reflog entry (different physical directory), how can I cherry-pick this, or can I?

I'm using git-svn. My first branch is using git-svn of the trunk of a Subversion repo, and the next branch is using git-svn on a Subversion branch.

Yes. Fetch the repository and then cherry-pick from the remote branch.

Here are the steps to add a remote, fetch branches, and cherry-pick a commit

# Cloning our fork
$ git clone [email protected]:ifad/rest-client.git

# Adding (as "endel") the repo from we want to cherry-pick
$ git remote add endel git://github.com/endel/rest-client.git

# Fetch their branches
$ git fetch endel

# List their commits
$ git log endel/master

# Cherry-pick the commit we need
$ git cherry-pick 97fedac

Source: https://coderwall.com/p/sgpksw

See How to create and apply a patch with Git. (From the wording of your question, I assumed that this other repository is for an entirely different codebase. If it's a repository for the same code base, you should add it as a remote as suggested by @CharlesB. Even if it is for another code base, I guess you could still add it as a remote, but you might not want to get the entire branch into your repository...)

Here's an example of the remote-fetch-merge.

cd /home/you/projectA
git remote add projectB /home/you/projectB
git fetch projectB

Then you can:

git cherry-pick <first_commit>..<last_commit>

or you could even merge the whole branch

git merge projectB/master

If you want to cherry-pick multiple commits for a given file until you reach a given commit, then use the following.

# Directory from which to cherry-pick
GIT_DIR=...
# Pick changes only for this file
FILE_PATH=...
# Apply changes from this commit
FIST_COMMIT=master
# Apply changes until you reach this commit
LAST_COMMIT=...

for sha in $(git --git-dir=$GIT_DIR log --reverse --topo-order --format=%H $LAST_COMMIT_SHA..master -- $FILE_PATH ) ; do 
  git --git-dir=$GIT_DIR  format-patch -k -1 --stdout $sha -- $FILE_PATH | 
    git am -3 -k
done

You can do it, but it requires two steps. Here's how:

git fetch <remote-git-url> <branch> && git cherry-pick FETCH_HEAD

Replace <remote-git-url> with the url or path to the repository you want cherry-pick from.

Replace <branch> with the branch or tag name you want to cherry-pick from the remote repository.

You can replace FETCH_HEAD with a git SHA from the branch.

Updated: modified based on @pkalinow's feedback.

Assuming A is the repo you want to cherry-pick from, and B is the one you want to cherry-pick to, you can do this by adding </path/to/repo/A/>/.git/objects to </path/to/repo/B>/.git/objects/info/alternates. Create this alternates files if it does not exist.

This will make repo B access all git objects from repo A, and will make cherry-pick work for you.

My situation was that I have a bare repo that the team pushes to, and a clone of that sitting right next to it. This set of lines in a Makefile work correctly for me:

git reset --hard
git remote update --prune
git pull --rebase --all
git cherry-pick -n remotes/origin/$(BRANCH)

By keeping the master of the bare repo up to date, we are able to cherry-pick a proposed change published to the bare repo. We also have a (more complicated) way to cherry-pick multiple braches for consolidated review and testing.

If "knows nothing" means "can't be used as a remote", then this doesn't help, but this SO question came up as I was googling around to come up with this workflow so I thought I'd contribute back.

You can do it in one line as following. Hope you are in git repository which need the cherry-picked change and you have checked out to correct branch.

git fetch ssh://[email protected]:7999/repo_to_get_it_from.git branchToPickFrom && git cherry-pick 02a197e9533
# 

git fetch [branch URL] [Branch to cherry-pick from] && git cherry-pick [commit ID]

The answer, as given, is to use format-patch but since the question was how to cherry-pick from another folder, here is a piece of code to do just that:

$ git --git-dir=../<some_other_repo>/.git \
format-patch -k -1 --stdout <commit SHA> | \
git am -3 -k

(explanation from @cong ma)

The git format-patch command creates a patch from some_other_repo's commit specified by its SHA (-1 for one single commit alone). This patch is piped to git am, which applies the patch locally (-3 means trying the three-way merge if the patch fails to apply cleanly). Hope that explains.