Git cheat sheet¶
When you clone a repository from GitLab or GitHub, the
git clone command
adds a remote named "origin", pulls down all Git data, creates a pointer named
origin/master to the remote's master branch, and a pointer master to your
own local master branch, starting at the same place as origin’s master branch.
My summary after reading the Branching chapter of Scott Chacon's Pro Git book:
master : the default branch that will be selected after cloning your repo. The name is purely conventional and has no special meaning for Git itself.
HEAD : pointer to the "current branch" (the one that is checked out).
Create a new branch called "20141022":
git branch 20141022
Select a branch :
git checkout 20141022
Shortcut to create and select :
git checkout -b 20141022
Starting and selecting a branch will not modify your local modifications.
List all branches:
See which branches are already merged into HEAD :
git branch --merged
See all the branches that contain work you haven’t yet merged :
git branch --merged
Merge a branch into current branch:
git merge 20141022(in case of a merge conflict, start reading at Basic Merge Conflicts)
Delete a branch:
git branch -d 20141022
Common names for long-term branches: develop, proposed, next.
When you want to share a branch with the world, you need to push it to a remote that you have write access to. For example:
$ git checkout -b myfeature # create a local branch $ git push origin myfeature # make it public $ # ... add files and commit changes
Remote branches :
TODO: Continue to read https://git-scm.com/book/en/Git-Branching-Remote-Branches
Most projects don't use the "shared repository model" (several users writing to a repo) but the "fork & pull" model as explained in Using pull requests).
Example: I have a fork of Ahmet's ablog project. Ahmet made changes in ablog and asked me to test them. So I need to merge his changes into the local copy of my fork.
So if I want to contribute to Ahmet's ablog project, I need to fork the project on GitHub (using their web interface) and then get a clone of this fork:
$ git clone email@example.com:lsaffre/ablog.git
Now I make my changes:
$ e ablog/__init__.py
When I decided that I want to share my local changes, I create a branch, commit it and push it to my repo:
$ git checkout -b feed_encoding $ git commit -m "Added encoding utf-8 to file atom.xml" $ git push origin feed_encoding
Now their web interface sees my branch and allows me to turn it into a pull request.
Every local project repository has a set of tracked repositories, also called "remotes". The default remote (the place from where my local repo has been taken) is called origin.
List all remotes:
$ git remote -v origin firstname.lastname@example.org:lsaffre/ablog.git (fetch) origin email@example.com:lsaffre/ablog.git (push)
First I must add Ahmet's repo as a new remote, which is usually called upstream:
$ git remote add upstream firstname.lastname@example.org:abakan/ablog.git
My local repo now has two remotes:
$ git remote -v origin email@example.com:lsaffre/ablog.git (fetch) origin firstname.lastname@example.org:lsaffre/ablog.git (push) upstream email@example.com:abakan/ablog.git (fetch) upstream firstname.lastname@example.org:abakan/ablog.git (push)
Now I can fetch all changes from the upstream repository:
$ git fetch upstream
Before continuing, make sure where you want the changes from upstream to go. Usually you want them to go to master, so you must select this branch:
$ git checkout master
And finally I can merge them into my local repo:
$ git merge upstream/master
fetch upstream looks up the specified remote, fetches any data from
it that you don’t yet have, and updates your local database, moving
upstream/master pointer to its new position.
You can rewrite the most recent commit message with
$ git commit --amend -m "new commit message"
This will change the commit id, i.e. actually you are creating a new commit that replaces the old one.
How to return back to my local changes?
What was this?
$ git pull upstream master
I had started a branch in my local copy of ablog:
$ git status On branch trans_estonian nothing to commit, working directory clean $ git push origin trans_estonian Everything up-to-date
Example: cuchac posted a pull request for a branch which he named
export_excel_datetime (on his fork of project lino).
Check that there are no local changes in my repo:
$ go lino $ git status On branch master Your branch is up-to-date with 'origin/master'. nothing to commit, working directory clean
Check out his branch into a new branch
inbox in order to test the
$ git checkout -b inbox master $ git pull email@example.com:cuchac/lino.git export_excel_datetime remote: Counting objects: 6, done. remote: Compressing objects: 100% (3/3), done. remote: Total 6 (delta 4), reused 5 (delta 3) Unpacking objects: 100% (6/6), done. From github.com:cuchac/lino * branch export_excel_datetime -> FETCH_HEAD Merge made by the 'recursive' strategy. lino/modlib/export_excel/models.py | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
Test the changes:
$ inv test [localhost] local: python setup.py -q test ........................................... ---------------------------------------------------------------------- Ran 43 tests in 36.290s OK Done.
Reactivate master and merge the changes:
$ git checkout master M docs/tutorials/pisa/pisa.Person-1.pdf Switched to branch 'master' Your branch is up-to-date with 'origin/master'. $ git merge --no-ff inbox Merge made by the 'recursive' strategy. lino/modlib/export_excel/models.py | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
Note: is the
--no-ff option necessary?
Push everything to the master:
$ git push origin master Counting objects: 43, done. Delta compression using up to 4 threads. Compressing objects: 100% (11/11), done. Writing objects: 100% (11/11), 1.39 KiB | 0 bytes/s, done. Total 11 (delta 8), reused 0 (delta 0) To firstname.lastname@example.org:lsaffre/lino.git 988adf9..55961b9 master -> master
And finally delete the
$ git branch -v --merged inbox bfd3f39 Merge branch 'export_excel_datetime' of github.com:cuchac/lino into inbox * master 55961b9 Merge branch 'inbox' $ git branch -d inbox Deleted branch inbox (was bfd3f39).
git fetch origin pull/999/head:my-branch git checkout my-branch
999 is the number of the pull request and
my-branch the name of