TubeTK/Development/GITCheatSheet

Policy

Just because a thing can be done with git doesn't mean it should be done.

• Please don't revise history after it's been made publicly available (i.e. don't revise history after a "git push")

These instructions

Whenever these instructions refer to origin or upstream, they assume you've setup your development environment according to the instructions on Git Usage and Procedures

Workspace tips

Show the current branch in your prompt: add the following to your .bashrc

PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\[\033[01;33m\]`git branch 2>/dev/null|cut -f2 -d\* -s|sed -e"s/ //g"`\[\033[00m\]\$ '

gitk is a great tool for visualizing the git history and seeing where your master or branch is with respect to origin:master

gitk

git gui is a great tool for performing git commands via a graphical user interface

git gui

Use a global ignore file for editor backups

Different developers' editors use different backup file names. Rather than put every possible editor backup file name in every project .gitignore, use a personal gitignore file to ignore your own editor backup files:

git config --global core.excludesfile ~/.gitignore
echo '*~' >> ~/.gitignore

Now, the exclusion pattern '*~' will be applied in every directory of every git project you use.

Work with branches

To list the branches in your local repository:

git branch

To list all the branches in the remote repositories:

git branch -r

To create a local branch:

git branch branch_name

To check out a new local branch based off of a published branch:

git checkout -b branch_name upstream/branch_name

To checkout a new local branch based off another local branch:

git checkout -b new_branch_name existing_branch_name

After you branch, you can switch freely between master and your branch:

git checkout master
git checkout branch_name

To work on the Beta branch instead of master:

git branch --track vBeta upstream/vBeta
git checkout vBeta

Remove a local branch:

git checkout master
git branch -d <branch>

Delete a remote branch

• Don't do this unless you're incredibly confident in what you're doing

git push origin :branch_name

If you prefer to use different directories for different branches

The following sequence creates "tubetk-vBeta" alongside "tubetk", then uses 'git relink' to save disk space, then switches to the vBeta in the tubetk directory:

cp -r tubetk/ tubetk-vBeta
git relink tubetk-vBeta/ tubetk/
cd tubetk-vBeta
git branch vBeta origin/vBeta 
git checkout vBeta

Check with tubetk developers before pushing changes to vBeta. If your bugfix is approved for vBeta, then it will also be fixed on master when changes in the branch are merged up.

Commits

Add to local commit:

git add <filename>
git add -A

Push local commits to your personal public gitorious repository:

git push origin branch_name

View history

(You can also view the history online on gitorious, but viewing the history locally is often more powerful.)

Take a look at the history:

• git log has a bunch of options; this set detects renames and copies, and shows a summary of what files are changed in each commit:

git log -C --stat

Get a closer look at a particular change by commit:

• -p shows a patch, -1 restricts to a single change, and 57c609 is the start of a commit shown by the first 'git log' command

git log -C -p -1 57c609

Get a list of commits to a particular file since vBeta branch:

git log --oneline vBeta..origin/v1.0 -- CMakeLists.txt

View history graphically, if you installed the necessary program:

gitk --all
qgit --all

View commits affecting a certain file only:

git whatchanged filename

Working with a stash

Stash local changes temporarily:

git stash

Stash only those changes that have not been staged:

git stash save --keep-index

Get stashed local changes:

git stash pop

Update a branch to the remote master's head (assuming origin master is up to date):

git stash # Push your uncommitted local changes to a stack.  Be careful, they are not saved anywhere else.
git rebase origin master
git stash pop # To re-apply the changes on the stack to the local repository

Get changes from others

From the central repository

To get changes that have been committed to the TubeTK central repository.

git checkout master
git fetch upstream
git merge upstream/master
git push origin master

From other repositories

Pull changes made by another developer in his/her public repository, but not yet committed to the central repository:

git pull git://<some-other-repo>.git master

'git remote' can be used to manage short names for repositories that you frequently pull from.

From patches

Apply a patch from another developer, preserving the other developer's identity as the patch author:

git am --signoff patch.mbox

Prepare commits to share with fellow developers

With git, it's possible to record every edit and false start as a separate commit. This is very convenient as a way to create checkpoints during development, but often you don't want to share these false starts with others.

Git provides two main ways to do this, both of which can be done freely before you share the change:

• 'git commit --amend' lets you make additional changes a part of the last thing you committed, optionally modifying the commit message as well. Use this if you realized right away that you left something out of the commit, or if you typo'd the commit.
• 'git rebase --interactive origin' lets you go back through each change made since 'origin', possibly editing it or combining ('squashing') it with another change. In the most extreme case, you can 'squash' it into a single commit, if there's no value to other developers in seeing the individual steps.
  • For example, to squash the most recent four commits into one commit:

git rebase --interactive HEAD~4
change all lines except the first one to “squash” instead of “pick”, and save (note list of commits is backwards, from oldest at top to newest at bottom)
edit the commit message, and save

• At any time, to abort the rebase:

git rebase --abort

Send patches through e-mail or the web

When you think your changes are ready to be used by others, you can share it in the form of a patch. Make a series of patches for each commit in your local branch but not in 'upstream':

git format-patch -M upstream

This creates a number of files with names like

0001-my-well-intentioned-change.patch

These patch files are suitable for putting on a webserver or for sending as e-mail with your favorite mail client or git-send-email (some configuration required).

To submit a patch, email it to one of the TubeTK Developers.

Additional References

• GIT tutorial
• GIT guide from gitorious
• GIT guide in CMake
• GIT quick reference
• A visual git reference

[Category:TubeTK]]