Copying an untracked folder to another branch

Question

Is there a way to copy an untracked folder to another branch?

I know you can copy tracked folders to another branch by doing something like this:

git checkout mybranch
git checkout master -- myfolder

But is there a way to copy a folder that isn't tracked on master, but is tracked on the branch I want to copy to?

I'm trying to do this for GitHub pages and I'm following this guide, but he commits to master and pushes it to upstream gh-pages. I don't want to do that. I just want my build to generate the docs and copy the untracked docs to another branch and then push them upstream.

Answer 1

What you have here is a situation that you have some untracked files which conflict with tracked files in another branch. You'd like to switch to that branch, but checkout won't let you.

The "first level" solution in git is to promote these untracked files to the index:

git add folder

Now you still cannot check out to the branch. However, you are presented with a new possibility: you can git stash save the changes:

git stash save

Now you can switch to the branch, and do a git stash pop. At this point you can deal with merge conflicts, if any, followed by a git reset and you're done.

[Update: the git add is not necessary because git stash has an option to include untracked files!]

Let's work through a complete example, involving a single file called topicfile which exists only in a branch, and is created as a working file while on master, but with different contents:

~$ mkdir gittest
~$ cd gittest/
~/gittest$ git init
Initialized empty Git repository in /home/kaz/gittest/.git/
~/gittest$ touch emptyfile
~/gittest$ git add emptyfile
~/gittest$ git commit -m "starting repo"
[master (root-commit) 75ea7cd] starting repo
 0 files changed
 create mode 100644 emptyfile
~/gittest$ git branch
* master
~/gittest$ git checkout -b topic
Switched to a new branch 'topic'
~/gittest$ cat > topicfile
a
b
c
d
e
~/gittest$ git add topicfile
~/gittest$ git commit -m "topicfile"
[topic 875efc5] topicfile
 1 file changed, 5 insertions(+)
 create mode 100644 topicfile
~/gittest$ git checkout master
Switched to branch 'master'
~/gittest$ ls
emptyfile
~/gittest$ cat > topicfile
@
a
b
c
d
e
f
g
h
~/gittest$ git add topicfile
~/gittest$ git stash save topicfile
Saved working directory and index state On master: topicfile
HEAD is now at 75ea7cd starting repo
~/gittest$ git checkout topic
Switched to branch 'topic'
~/gittest$ git stash pop
Auto-merging topicfile
CONFLICT (add/add): Merge conflict in topicfile
~/gittest$ cat topicfile
<<<<<<< Updated upstream
=======
@
>>>>>>> Stashed changes
a
b
c
d
e
<<<<<<< Updated upstream
=======
f
g
h
>>>>>>> Stashed changes
~/gittest$ cat > topicfile  # resolve in favor of stashed changes:
@
a
b
c
d
e
f
g
h
~/gittest$ git add topicfile
~/gittest$ git reset
Unstaged changes after reset:
M       topicfile
~/gittest$ git diff
diff --git a/topicfile b/topicfile
index 9405325..bea0ebb 100644
--- a/topicfile
+++ b/topicfile
@@ -1,5 +1,9 @@
+@
 a
 b
 c
 d
 e
+f
+g
+h

At this point we can commit our topicfile changes to the topic branch, and the file is still not tracked on master.

Because there were conflicts in git stash pop, the stash still exists. We can clean that away with git stash drop.

The alternative to all this is to not only git add the untracked files to the index, but to git commit that to make a proper commit. Then we can cherry pick the commit into the branch. If we don't want those files tracked on master, that is okay: we can later git reset --hard HEAD^ on master to eliminate that commit.