GIT, a distributed version control system
GIT overview
Git is a distributed version control system. Unlike Subversion, this means whole copies of the repository can exist in multiple locations. In practice there is usually the notion of a central repository.
Hosted solutions
Stash has been renamed to Bitbucket Server, it is a self-hosted option.
Remote repositories
Remote repositories are git repositories that you can push changes to, or pull changes from. It is possible to have multiple remote repositories.
When a repo is initially cloned, a remote named origin is tracked that will point to the original repo.
To list all the remote repositories, run
git remote
To see all the URLs of the remote repositories, run
git remote -v
To find out the URL of the origin repo, run
git config remote.origin.url
It will print out the URL.
To change the remote URL for the remote named origin:
git remote set-url origin git@example.com:magicmonster/example.git
Setting your username and email
This can be configured globally or per repository
To change it for the current repo, set the config values user.name and user.email
git config user.email email@example.com
git config user.name "Joe Bloggs"
To change it for your user, use the –global option.
git config --global user.email email@example.com
Migrating from Subversion
See migrating to git
Ignoring files
Add a .gitignore which contains a list of file patterns that git should ignore. See the
gitignore documentation for detailed info.
SSH keys
gitolite, github, and bitbucket all support SSH keys. If you don’t already have a keypair, create one
using ssh-keygen, then you can use it for both authentication and identification.
Branching
Branching is different in git to subversion. You can have local only branches, which allows for different workflows.
Branch Creation
Local branch creation
Switch to your source branch, then checkout and create your new branch. In the following example feature/foo
is the original branch, and feature/foofix is the new branch.
git checkout feature/foo
git checkout -b feature/foofix
fatal: Failed to lock ref for update: Not a directory
error: unable to resolve reference refs/heads/feature/foo/fix: Not a directory
fatal: Failed to lock ref for update: Not a directory
This happened when trying to create a branch named feature/foo/fix. This is not allowed if a basename
or parent branch called feature/foo already exists.
Remote branch creation
If you are using a hosted solution, you can do this via the UI.
After it has been created, check it out to your local. In the following example it is assumed your branch is named ‘quickfix’.
git checkout -b quickfix origin/quickfix
To create a remote branch from an existing local branch named feature/quickfix, you need to push it.
git push origin feature/quickfix
Branch cleanup
Remove invalid remote tracking branches
The remote origin branch may have been removed, but your local branch still refers to it. This could happen when a pull request has been merged.
git remote prune origin
This will prune references to invalid remote origin branches.
Show merged branches
If a branch has been merged, it makes sense to delete it. I do this for feature branches that have been merged into master.
First list the branches that have been merged
git branch --merged
Delete a local branch
git branch -d foo
Reset branch
Sometimes you do not want to push your changes to the remote branch. You can reset your local branch with the following command:
git checkout quickfix
git reset --hard origin/quickfix
Merging
Switch to the target branch, then merge commits from the source branch.
git checkout target
git merge source
where source and target are branch names.
Pushing
There is a difference between author and committer. This can happen when you are merging commits authored by people on different branches. There may be special hooks added to the remote git repo that checks your pushes and may reject them. If you are using IntelliJ, use the command line instead to see the error message. e.g. Bitbucket can have hooks that checks that the name and email is valid within the organisation.
Export repo
If you are interested in an export of only the source code, use the git archive subcommand.
To access a remote repo, use the remote option.
git archive --remote git@example.com:example/example.git --output example.tar master