Merge pull request #14 from nsidc/cherry-pick-1

Post about `cherry-pick`
nsidc · Sep 28, 2023 · 31af9ee · 31af9ee
2 parents 7bea8c1 + 09f1b50
commit 31af9ee
Show file tree

Hide file tree

Showing 15 changed files with 101 additions and 0 deletions.
diff --git a/posts/git-cherry-pick/index.md b/posts/git-cherry-pick/index.md
@@ -0,0 +1,99 @@
+---
+title: "Cherry-Pick on GitHub"
+author: "Robyn Marowitz"
+date: "2023-09-26"
+description: "Committing a mistake in GitHub can feel so scary. Cherry picking is a tool to help you fix your history when something like that happens. This post lays out instructions on the cherry picking method."
+categories: [github, open-science]
+image: "cherry_pick.jpeg"
+---
+
+## What is `git cherry-pick`?
+
+It is the act of picking a commit from one branch and applying it to another branch.  
+Read more in the [official docs](https://git-scm.com/docs/git-cherry-pick)
+
+## When should I use `git cherry-pick`?
+
+`cherry-pick` is best used when a change has been committed onto a different branch than desired. You can *pick* commits one by one or by choose a range and move them to the desired branch. 
+
+```
+git cherry-pick <commit>
+git cherry-pick <commit A> <commit B>
+git cherry-pick <commit A>...<commit C>
+```
+
+### How is `cherry-pick` different than `rebase`?
+
+`git cherry-pick` usually brings a commit from somewhere else and applies it on top of your current branch, recording a new commit, while `git rebase` reapplies commits on top of another base tip.
+
+`cherry-pick` is simpler and less risky. `rebase` is a valuable tool, but if you don't understand what it's doing, you can get in trouble pretty easily.
+
+`rebase` will likely be covered in a future post. 
+
+## Git command/syntax:
+
+When using cherry pick it is very important to look at your git log and understand what is going on.
+
+First it can be useful to look at the branches you have. I did this with the `git branch` command and as you can see the one with the asterik and in green is the branch I am currently on. 
+
+![](show-branches.png)
+
+I use `git lola` which is an alias:  `lola = log --graph --decorate --oneline --all`. I highly recommending adding this alias to your `.gitconfig`. 
+
+![](lola-1.png)
+
+
+Here you can see that I have the `cherry-pick-post` branch checked out, as indicated by the `HEAD` ref. I have made changes to the about section which I actually wanted to do on the main branch. So I will use `git cherry-pick` to make that happen. First you want to be sure you are on the branch that you want to put the commit on.
+
+![](status-on-cpp-branch.png)
+
+I can see I am on the `cherry-pick-post` branch but I want the new commits to be created on `main`, so I will use `git switch` to go to the `main` branch. 
+
+![](switch-main.png)
+
+Now I am on the desired branch so I can go ahead and cherry-pick using the syntax `git cherry-pick <commit>`.
+
+![](pick-commit-1.png)
+
+To see what this did we will once again do `git lola`:
+
+![](lola-after-pick1.png)
+
+Now the `Update about page` commit is on both the `cherry-pick-post` branch and the `main` branch. Note that the commit ID on the `main` branch is a new ID, but the original commit  on `cherry-pick-post` branch has the same ID as before.
+
+We will now push and look at the log again. 
+
+![](push-and-lola.png)
+
+At this point `main` appears exactly as we want it to, but `chery-pick-post` still has the unwanted commit. 
+
+So at this point we will once again use the cherry-pick command to move forward. I will create a new branch called `cherry-pick-1` from the main branch.
+
+![](new-branch.png)
+
+Now at this point I want to take everything from the old `cherry-pick-post` branch and pick it to my new branch. 
+
+There are 3 commits that I want so I can actually pick them all a once. 
+
+`git cherry-pick 9e5da76 463956b 3edb3ee`
+
+![](pick-2.png)
+
+Git gives a great summary of what is happening and shows the commits I am picking. 
+To see where I am at I will do `git lola` once again.
+
+![](lola-2.png)
+
+At this point I have the 3 commits I want on my new branch so I can go ahead and push that branch. `git push -u origin cherry-pick-1`
+
+![](lola-3.png)
+
+Now I no loger want the old branch so I will delete it using `git branch -D cherry-pick-post` this will only delete it locally, so I will also need to do `git push origin :cherry-pick-post` to delete the branch from GitHub.
+
+Note: Git may keep untracked history for around 2 weeks so there is always time to alter if you decide you want to revive something. 
+
+## Summary
+
+Cherry picking is a tool for copying commit(s) from one branch to another.
+It is important to remember that this is a powerful tool and you should proceed with caution when using it to copy a commit(s) to a different branch. 
+Learning `cherry-pick` is a useful step on the way to learning about `rebase` - which will be covered in this space soon. 
diff --git a/posts/git-cherry-pick/lola-1.png b/posts/git-cherry-pick/lola-1.png
diff --git a/posts/git-cherry-pick/lola-2.png b/posts/git-cherry-pick/lola-2.png
diff --git a/posts/git-cherry-pick/lola-3.png b/posts/git-cherry-pick/lola-3.png
diff --git a/posts/git-cherry-pick/lola-after-pick1.png b/posts/git-cherry-pick/lola-after-pick1.png
diff --git a/posts/git-cherry-pick/new-branch.png b/posts/git-cherry-pick/new-branch.png
diff --git a/posts/git-cherry-pick/pick-2.png b/posts/git-cherry-pick/pick-2.png
diff --git a/posts/git-cherry-pick/pick-commit-1.png b/posts/git-cherry-pick/pick-commit-1.png
diff --git a/posts/git-cherry-pick/pick2.png b/posts/git-cherry-pick/pick2.png
diff --git a/posts/git-cherry-pick/push-and-lola.png b/posts/git-cherry-pick/push-and-lola.png
diff --git a/posts/git-cherry-pick/show-branches.png b/posts/git-cherry-pick/show-branches.png
diff --git a/posts/git-cherry-pick/status-on-cpp-branch.png b/posts/git-cherry-pick/status-on-cpp-branch.png
diff --git a/posts/git-cherry-pick/switch-main.png b/posts/git-cherry-pick/switch-main.png
diff --git a/posts/git-rebase/branch-list-2.png b/posts/git-rebase/branch-list-2.png
diff --git a/posts/git-rebase/index.md b/posts/git-rebase/index.md
@@ -0,0 +1,2 @@
+# Note: 
+-- Rebase does not re-write hitory because you cannot change a commit, it creates a new history
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		# Note:
		-- Rebase does not re-write hitory because you cannot change a commit, it creates a new history