Git's not what you think it is Abizer Nasir 

Why Am I Here? • I’ve been convincing people to use try git since 2009. • I’ve since become a version control “rubber duck”. 

What This Talk Is Not • A git tutorial • Reasons to use X over any other DVCS • A handy list of commands for you to use 

What I Will Talk About • Some misconceptions about Git and some different ways of thinking about Version control. • I prefer questions at the end, but please don’t let that stop you if you really want to raise your hand. 

Git Is Not Just Version Control 

Git Is A Safety Rope • Mark safe points as the code develops. • Easier to trash changes to a known point than to manually edit back to it. • Small, frequent changes that can be rolled up into more atomic commits. http://www.flickr.com/photos/mariachily/3382813383/ 

Git Is Communication • With your colleagues • With your clients • With your future or parallel self • A stored conversation about the history of a code base 

Write Good Commit Messages • Short first line (less than 50 chars) in the present imperative tense. • “change” not “changes” • A blank line: • Body, wrapped to less than 80 chars, that provides more information about the commit. • Describe what applying the change will do, not what was done to create the change. 

Example Fixes issue #X in production ! This change uses a algorithm Y which is faster than than W. ! - I’m using a bullet point, for a list of changes. - I usually don’t need to list the changed files. 

Git Is Not A Silver Bullet 

Help Git to Help You • Merge conflicts can still happen. Small commits that affect minimum subsets are easier to manage. • Git is not a substitute for project management. If many changes are happening to the same place in the same file, there will be conflicts. • Branches are cheap. Tags are cheap. Don’t be tempted to clean history too often. • Multiple repositories as backups are a good idea. 

Git Allows History To Be Rewritten 

“Git is evil because it lets you change history” 

Changing History Is Bad When… • You change the history of any branch that somebody else is likely to have cloned and made changes to. 

Changing History Is Not Bad When… • You are on a local branch that is not shared with anybody else. • You are on a branch that is synced with a private repository that only you use. • You roll up your list of small individual commits on your working branch into a larger atomic commit that you then push. • rebase is your friend. Seriously. 

Reflog Is Your Lifeguard • Every change to HEAD is recorded. • State can be reconstructed using the shas. 

Avoid pulling changes • Use `git fetch` and then inspect the upstream changes. • Use `git remote update` to fetch changes if the repository has multiple remotes. • Merge or rebase onto a temporary branch if you aren’t sure if the changes will apply cleanly. 

You Don’t Need A GUI To Work With Git 

gitk 

git gui 

git log --oneline 

git log --graph --pretty=format:'%Cred%h %Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit 

Magit (emacs) 

Git Is Not Just For Text Based Code 

www.kaleidoscopeapp.com 

Git Can Be Used With A Team Of Mixed Ability 

Risks • Inexperienced team members (or clients) may mess up the repository. • History may be lost. • It could become hard to track development / test / production branches. 

Protections • You don’t need to use every bit of git: add, push, commit, pull, fetch, checkout, status, are usually enough to get started • Git objects are immutable, changes are not irrevocable. Errors can be corrected. • Well named branches and a set of conventions are a great help. • Make people care, and they will care. Everyone wants to do a good job. 

Git Flow • github.com/nvie/gitflow • datasift.github.io/gitflow • A set of scripts and workflows to define branching and merging. • Not everyone’s cup of tea but it helps when getting used to version control in a team. 

Git Does Not Require Branches To Be Related 

Independent Branches • I’m sure you’ve seen the gh-pages feature on github • `git checkout --orphan ` 

Branches Are Cheap • Never be afraid to create a branch. They are cheap. • Use some sort of naming convention so that you don’t get confused about them. • You can create a description for a branch • git branch --edit-description • If you want to park a branch - Create an annotated tag with a description. 

Related Branches • Keep the main code in one branch. • Create a separate branch for a demo that uses the main code. • Use rebase liberally when only one branch is being used for development, but be sure to make it clear which the non-development branch is. • Use `cherry-pick` if changes are made in both branches. 

Example 

Git Is Not Hard 

Err… 

Git Can Be Difficult 

132 Commands add am archive bisect branch bundle checkout cherry-pick citool clean clone commit describe diff fetch format-patch gc grep gui init log merge mv notes pull push rebase reset revert rm shortlog show stash status submodule tag gitk apply checkout-index commit-tree hash-object index-pack merge-file merge-index mktag mktree pack-objects prune-packed read-tree symbolic-ref unpack-objects update-index update-ref write-tree cat-file diff-files diff-index diff-tree for-each-ref ls-files ls-remote ls-tree merge-base name-rev pack-redundant rev-list show-index show-ref tar-tree unpack-file var verify-pack check-attr check-ref-format fmt-merge-msg mailinfo mailsplit merge-one-file patch-id peek-remote sh-setup stripspace daemon fetch-pack http-backend send-pack update-server-info http-fetch http-push parse-remote receive-pack shell upload-archive upload-pack config fast-export fast-import filter-branch lost-found mergetool pack-refs prune reflog relink remote repack replace repo-config annotate blame cherry count-objects difftool fsck get-tar-commit-id help instaweb merge-tree rerere rev-parse show-branch verify-tag whatchanged archimport cvsexportcommit cvsimport cvsserver imap-send quiltimport request-pull send-email svn 

Porcelain / Plumbing add am archive bisect branch bundle checkout cherry-pick citool clean clone commit describe diff fetch format-patch gc grep gui init log merge mv notes pull push rebase reset revert rm shortlog show stash status submodule tag gitk apply checkout-index commit-tree hash-object index-pack merge-file merge-index mktag mktree pack-objects prune-packed read-tree symbolic-ref unpack-objects update-index update-ref write-tree cat-file diff-files diff-index diff-tree for-each-ref ls-files ls-remote ls-tree merge-base name-rev pack-redundant rev-list show-index show-ref tar-tree unpack-file var verify-pack check-attr check-ref-format fmt-merge-msg mailinfo mailsplit merge-one-file patch-id peek-remote sh-setup stripspace daemon fetch-pack http-backend send-pack update-server-info http-fetch http-push parse-remote receive-pack shell upload-archive upload-pack config fast-export fast-import filter-branch lost-found mergetool pack-refs prune reflog relink remote repack replace repo-config annotate blame cherry count-objects difftool fsck get-tar-commit-id help instaweb merge-tree rerere rev-parse show-branch verify-tag whatchanged archimport cvsexportcommit cvsimport cvsserver imap-send quiltimport request-pull send-email svn 

You Don’t Need To Use It ALL • add • commit • fetch • merge • branch • checkout • push • status 

Be Brave. Be Bold 

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Start With The Basics • Use the basic commands to start with. Start using automation when you become comfortable with them. • Use a GUI if you have to. • If you want to do something complex, look it up and try to do it. Repetition builds knowledge. • Learn the Git object model, and everything becomes a lot clearer. 

Be Brave, Bold, And Calm 

Thank You! Abizer Nasir | @abizern | abizern.org | 365git.tumblr.com