开发者

Create a branch in Git from another branch

开发者 https://www.devze.com 2023-01-31 06:30 出处:网络
I have two branches: master and dev I want to create a "feature branch" from the dev branch.

I have two branches: master and dev

I want to create a "feature branch" from the dev branch.

Currently on the branch dev, I do:

git checkout -b myfeature dev

... (some work)

git commit -am "blablabla"
git push origin myfeature

But, after visualizing my branches, I go开发者_如何转开发t:

--**master**
------0-----0-----0-----0-----0
------------------------**dev**----**myfeature**

I mean that the branch seems fast-forward merged, and I don't understand why...

What am I doing wrong?

How can you branch off from another branch and push back to the remote repository for the feature branch?

All that in a branching model like the one described here.


If you like the method in the link you've posted, have a look at Git Flow.

It's a set of scripts he created for that workflow.

But to answer your question:

git checkout -b myFeature dev

Creates the MyFeature branch off dev. Do your work and then

git commit -am "Your message"

Now merge your changes to dev without a fast-forward

git checkout dev
git merge --no-ff myFeature

Now push the changes to the server

git push origin dev
git push origin myFeature

And you'll see it how you want it.


If you want create a new branch from any of the existing branches in Git, just follow the options.

First change/checkout into the branch from where you want to create a new branch. For example, if you have the following branches like:

  • master
  • dev
  • branch1

So if you want to create a new branch called "subbranch_of_b1" under the branch named "branch1" follow the steps:

  1. Checkout or change into "branch1"

     git checkout branch1
    
  2. Now create your new branch called "subbranch_of_b1" under the "branch1" using the following command.

     git checkout -b subbranch_of_b1 branch1
    

    The above will create a new branch called subbranch_of_b1 under the branch branch1 (note that branch1 in the above command isn't mandatory since the HEAD is currently pointing to it, you can precise it if you are on a different branch though).

  3. Now after working with the subbranch_of_b1 you can commit and push or merge it locally or remotely.

Create a branch in Git from another branch

Push the subbranch_of_b1 to remote:

 git push origin subbranch_of_b1


Create a Branch

  • Create branch when master branch is checked out. Here commits in master will be synced to the branch you created.

    git branch branch1

  • Create branch when branch1 is checked out . Here commits in branch1 will be synced to branch2 git branch branch2


Checkout a Branch

git checkout command switch branches or restore working tree files

  • git checkout branchname

Renaming a Branch

  • git branch -m branch1 newbranchname

Delete a Branch

  • git branch -d branch-to-delete
  • git branch -D branch-to-delete ( force deletion without checking the merged status )

Create and Switch Branch

  • git checkout -b branchname

Branches that are completely included

  • git branch --merged


Branch Differences [ git diff branch1..branch2 ]

Multiline difference

  • git diff master..branch1

Singleline difference

  • git diff --color-words branch1..branch2


Various ways to create a branch in Git from another branch:

This answer adds some additional insight, not already present in the existing answers, regarding just the title of the question itself (Create a branch in Git from another branch), but does not address the more narrow specifics of the question which already have sufficient answers here.

I'm adding this because I really needed to know how to do #1 below just now (create a new branch from a branch I do not have checked out), and it wasn't obvious how to do it, and Google searches led to here as a top search result. So, I'll share my findings here. This isn't touched upon well, if at all, by any other answer here.

While I'm at it, I'll also add my other most-common git branch commands I use in my regular workflow, below.

1. To create a new branch from a branch you do not have checked out:

Create branch2 from branch1 while you have any branch whatsoever checked out (ex: let's say you have master checked out):

git branch branch2 branch1

The general format is:

git branch <new_branch> [from_branch]

man git branch shows it as follows. What I call <new_branch> is what they call <branchname>, and what I call [from_branch] is what they call [<start-point>]:

git branch [--track | --no-track] [-l] [-f] <branchname> [<start-point>]

2. To create a new branch from the branch you do have checked out:

git branch new_branch

This is great for making backups before rebasing, squashing, hard resetting, etc.—before doing anything which could mess up your branch badly.

Example: I'm on feature_branch1, and I'm about to squash 20 commits into 1 using git rebase -i master. In case I ever want to "undo" this, let's back up this branch first! I do this ALL...THE...TIME and find it super helpful and comforting to know I can always easily go back to this backup branch and re-branch off of it to try again in case I mess up feature_branch1 in the process:

git branch feature_branch1_BAK_20200814-1320hrs_about_to_squash

The 20200814-1320hrs part is the date and time in format YYYYMMDD-HHMMhrs, so that would be 13:20 hours (1:20 pm) on 14 Aug. 2020. This way I have an easy way to find my backup branches until I'm sure I'm ready to delete them. If you don't do this and you mess up badly, you have to use git reflog to go find your branch prior to messing it up, which is much harder, more stressful, and more error-prone.

Interjection: notes about git checkout vs git switch

  1. The classic, universal "Swiss army knife" which can do 1000 things: git checkout.
  2. The new and experimental alternative commands to git checkout: git switch + git restore.

git switch was added recently in Git v2.23. See your git version with git --version. It is designed to be an extremely limited form of git checkout, designed only to switch branches rather than also having the ability to check out or restore files, like git checkout can do. Read more here: https://www.git-tower.com/learn/git/commands/git-switch.

See also: What does git checkout still do after git switch got introduced?. git restore offers some of the rest of the functionality of git checkout which git switch does not contain.

Both man git switch and man git restore caution:

THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.

So, feel free to stick with git checkout if you like. Its behavior is not likely to change.

I pretty much just use git checkout myself, but you are welcome to use git switch (and git restore to restore or "check out" files) if you like.

3. To create and check out a new branch from the branch you do have checked out:

# the standard, "classic" command most people still use; `-b` stands
# for "create 'b'ranch"
git checkout -b new_branch

# the newer, "experimental" command now available as of Git v2.23; `-c` stands
# for "'c'reate branch"
git switch -c new_branch

To make it obvious what is happening there, know that this one command above is equivalent to these two separate commands:

# classic
git branch new_branch
git checkout new_branch

# OR: new/experimental as of Git v2.23
git branch new_branch
git switch new_branch

4. To create and check out a new branch from a branch you do not have checked out:

# classic
git checkout -b new_branch from_branch

# OR: new/experimental as of Git v2.23
git switch -c new_branch from_branch

To make it obvious what is happening there, know that this one command above is equivalent to these three separate commands:

# classic
git checkout from_branch
git branch new_branch
git checkout new_branch

# OR: new/experimental as of Git v2.23
git switch from_branch
git branch new_branch
git switch new_branch

5. To rename a branch

Just like renaming a regular file or folder in the terminal, git considered "renaming" to be more like a 'm'ove command, so you use git branch -m to rename a branch. Here's the general format:

git branch -m <old_name> <new_name>

man git branch shows it like this:

git branch (-m | -M) [<oldbranch>] <newbranch>

Example: let's rename branch_1 to branch_1.5:

git branch -m branch_1 branch_1.5

OR, if you already have branch_1 checked out, you can rename the currently-checked-out branch to branch_1.5 like this:

git branch -m branch_1.5

6. To create a new feature branch (feature2) based off of the latest upstream changes on main when you currently have feature1 checked out

Let's put a lot of what we learned above together to present a very common example we need to run whenever we finish one feature and need to start another one.

# The beginner/intermediate way

git checkout main           # check out main branch
git pull                    # pull latest upstream changes down
git checkout -b feature2    # create branch `feature2` from `main`, and check
                                # it out, all in one step`

# The advanced way

# [this is what I do--I'll explain why, below]
git fetch origin main:main      # pull latest upstream changes down from the
                                    # remote `main` branch, to the
                                    # locally-stored remote-tracking **hidden**
                                    # branch named `origin/main`, **and** to
                                    # the local `main` branch
git checkout -b feature2 main   # create branch `feature2` from `main`, and
                                    # check it out, all in one step`

# OR (nearly the same thing)
git fetch origin main           # pull latest upstream changes down from the
                                    # remote `main` branch, to the
                                    # locally-stored remote-tracking **hidden**
                                    # branch named `origin/main`. This does NOT
                                    # update the local `main` branch though!
git checkout -b feature2 origin/main # create branch `feature2` from
                                        # `origin/main`, and check it out, all
                                        # in one step`

So, when I'm on branch feature1, and have just finished it and am ready to start on a new feature2 based off of the latest main branch, why do I do this:

git fetch origin main:main
git checkout -b feature2 main

...instead of this?:

git checkout main
git pull
git checkout -b feature2

The answer, surprisingly, is that git checkout can be a horribly slow and heavy operation!—taking up to 3+ hours on a massive mono-repo utilizing git lfs post-checkout hooks in the repo's .git/hooks/post-checkout file. Let me explain. The .git/hooks/post-checkout file is an executable file containing a script that git will run after each time you run git checkout. If it contains a call to git lfs post-checkout "$@", then it may try to download 20+ GB of git lfs data (specific to the repo I work in—your scenario may vary) after running an innocent-looking git checkout. I don't want to do that! So, I skip the git checkout process to avoid that hassle and get started on my feature2 branch immediately without downloading all of that stuff I don't need first!

See also:

  1. Quick links to my answers I reference frequently and consider to be "git fundamentals":
    1. Various ways to create a branch in git from another branch
    2. All about checking out files or directories in git
    3. Who is "us" and who is "them" according to Git?
    4. How to use git diff filters via --diff-filter=
    5. How to use git lfs as a basic user: What is the difference between git lfs fetch, git lfs fetch --all, and git lfs pull?


To create a branch from another branch in your local directory you can use the following command.

git checkout -b <sub-branch> branch

For example:

  • the name of the new branch to be created is 'XYZ'
  • the name of the branch, 'ABC', under which 'XYZ' has to be created
git checkout -b XYZ ABC


Git 2.23 introduces git switch and git restore to split the responsibilities of git checkout.

Creating a new branch from an existing branch as of Git 2.23:

git switch -c my-new-branch

Switched to a new branch 'my-new-branch'

  • -c is short for --create and replaces the well-known git checkout -b

Take a look at this GitHub blog post explaining the changes in greater detail:

Git 2.23 brings a new pair of experimental commands to the suite of existing ones: git switch and git restore. These two are meant to eventually provide a better interface for the well-known git checkout. The new commands intend to each have a clear separation, neatly divvying up what the many responsibilities of git checkout


Do simultaneous work on the dev branch. In your scenario, the feature branch moves forward from the tip of the dev branch, but the dev branch does not change. It's easier to draw as a straight line, because it can be thought of as forward motion. You made it to point A on dev, and from there you simply continued on a parallel path. The two branches have not really diverged.

Now, if you make a commit on dev, before merging, you will again begin at the same commit, A, but now features will go to C and dev to B. This will show the split you are trying to visualize, as the branches have now diverged.

*-----*Dev-------*Feature

Versus

       /----*DevB
*-----*DevA
       \----*FeatureC


If you want to make a branch from some another branch then follow the below steps:

Assumptions:

  1. You are currently in the master branch.
  2. You have no changes to commit. (If you have any changes to commit, stash it!)
  3. BranchExisting is the name of branch from which you need to make a new branch with name BranchMyNew.

Steps:

  1. Fetch the branch to your local machine.

    git fetch origin BranchExisting : BranchExisting
    

This command will create a new branch in your local with same branch name.

  1. Now, from the master branch checkout to the newly fetched branch

    git checkout BranchExisting
    
  2. You are now in BranchExisting. Now create a new branch from this existing branch.

    git checkout -b BranchMyNew
    

Here you go!


For creating a branch from another one can use this syntax as well:

git push origin refs/heads/<sourceBranch>:refs/heads/<targetBranch>

It is a little shorter than "git checkout -b " + "git push origin "


Switch to the develop branch:

git checkout develop

Creates feature/foo branch of develop.

git checkout -b feature/foo develop

Merge the changes to develop without a fast-forward

git checkout develop
git merge --no-ff myFeature

Now push changes to the server:

git push origin develop
git push origin feature/foo


It's worked for me:

Go to your GitHub repository, and select the branch name from where you want to create a new branch, as shown in the below image:

Create a branch in Git from another branch

Then type the branch name you want to create, and click on Create branch.

Create a branch in Git from another branch

0

精彩评论

暂无评论...
验证码 换一张
取 消