Git primer

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Nov 142009
 

The is the very bare-bones basics of git.

First, I am staring by assuming that someone else has already setup a git repository on github. If it is a private repository, the author must grant you access to that repository by adding your github account name to the project.

Once this is done, you will see this project under “Your repositories.”

Every git project has a git URL associated with it. You will find this URL on the project’s page. It looks something like this:

git@github.com:johnsmith/mygreatproject.git

In this example “johnsmith” is the author’s github account and mygreatproject is the name of the project. You will find this URL in the Github interface – you can copy and paste it right from there. In fact, Github even provides a handy “Copy to clipboard” button just to the right of the URL in its interface.

With this, you execute git clone plus the Git URL to clone the repository to the current working directory.

git clone git@github.com:johnsmith/mygreatproject.git

Git will create a directory with the same name as the repository in your working directory and clone the repository into there. Next cd to that directory to start working with that project.

Branching. In all of the following examples, note that “xyz” is the name of your branch.

git checkout master first switch to the master branch
git push origin HEAD:refs/heads/xyz makes a new remote branch called “xyz”
git branch -a see what you just did. You should see master in green and (at least) two in red:
origin/master
origin/xyz
git checkout -b xyz --track origin/xyz Makes a new local branch xyz and tells git to push this branch back to the repository branch origin/xyz. You will see this result:
Branch xyz set up to track remote branch refs/remotes/origin/xyz.
Switched to a new branch “xyz”
git branch -a Now you should see both your master and your branch locally and on the remote repo.
 master
* xyz
 origin/master
 origin/xyz

If you mess up, you can delete a branch like this

git branch -D xyz delete the xyz local branch
git push origin :heads/xyz delete the xyz branch on the REMOTE server

Switching Between Branches

git checkout mybranch switches branches to “mybranch”
git checkout master switch back to master branch
git checkout -b xyz --track origin/xyz switches to the xyz and tells git to push the branch back to the origin

Committing, Pushing & Pulling

git status shows what you’ve changed
git add adds to index
git add .  add everything that’s been changed in current folder
git diff HEAD | mate show how my current version differs from the the HEAD
git commit -v commits my changes to my local repo (-v shows diff) (will open commit log, enter message at top of screen, then save & doc)
git push pushes all branhces
git push origin mybranch push mybranch to the “origin” server
git pull --rebase origin mybranch pull others’ changes by doing a rollback first, then applying your changes on top of what’s been changed since the last time you pulled

Resolving Conflicts

git stash (this will “stash” your changes away so you can pull)
git pull --rebase origin mybranch

If you get a conflict, fix the conflict (by editing the conflicted files and choose if you want to take the head’s version or your version), then

git add . adds the conflicted file back to the index
git rebase --continue continues the rebase option
git push Since we already have a commit created by the rebase, we don’t need another commit
git stash apply Applies the changes we stashed away before
then try committing & pushing and you shouldn’t get a conflict.

Miscellaneous

git log see log recent commits
git cherry-pick apply a specific commit to whatever branch you are in after you cherry-pick, do git push. is a long alphanumeric string that uniquely identifies this commit.
git reset --hard this will throw away changes you’ve made in your working branch

Merging Branches
This assumes that mybranch is branched from mystable. You are going to take any changes made to mystable since the time you branched onto the branch.

git checkout mybranch switch to mybranch branch if not already there
git merge mystable merge any work done on mystable INTO mybranch
git status to see what has conflicted
IF you have any conflicts, resolve your conflicts manually
git add . (either add all or just the ones that conflicted)
git commit -v put resolutions & dev changes into a commit. Do not do another commit if you are not resolving any conflicts.
git push Finally, put this back to your branch

Also see:

git --help

Color coding git:

git config --global color.ui “auto”

Going back in time.

git reset j89dh12783y39874283yry72eg983jd823e
git checkout – .

now you’re back at that commit
then to move forward again git pull

Rebasing strategy

git checkout master
git pull
git checkout some-other-branch
git rebase master

if there are conflicts, you’ll need to resolve them then do
git add .
git rebase --continue

once everything is all resolved, you need to push the newly-rebased branch up to github with a --force
git push origin some-other-branch --force

 Posted by at 10:22 pm

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