Hands-on commands

Checkout remote branch:
git checkout -b <name> origin/<name>

Checkout directory to given changeset:
git checkout 3257289075289037592abcde253 -- path/to/the/folder/

Multiple working trees sharing one repository:
git worktree add ../some/path/ branch
Checkouts branch under ../some/path/

Compare file with branch:
git diff mybranch otherbranch -- somefile

Transfer single commit between branches:

git checkout desired_branch
git cherry-pick commit_to_be_transferred_here_by_hash

git checkout orig_branch
#rollback commit
git reset --hard HEAD^

Branches

Checkout

Remote to local:
git checkout -b <local_branch_name> <remote_name>/<remote_branch_name>

Delete

Remote:
git push <remote_name> --delete <branch_name>

Locally:
git branch -d <local_branch_name>

Rename

First rename locally, then delete old branch on remote, finally push "new"

git branch -m old_branch new_branch   
git push origin :old_branch  
git push --set-upstream origin new_branch

Submodules

Project can depend on other projects. Root project is called superproject.
Submodule is always a commit in other repostiory. In other words: submodule points to particular commit.

Adding

git submodule add https://repo.url... [path] add submodule to project at path.
If no path is given then repo name is used.

Deleting

git submodule deinit <submodule>
git rm <submodule>
rm -rf .git/modules/asubmodule

Cloning

By default submodules are not cloned. In order to clone repository that contains submodules:

git clone <repo url>
git submodule init
git submodule update

Upgrading

In order to "upgrade" the submodule (actually submodule's commit):

cd submodule_dir
git checkout desired_branch
git pull
cd ..
git add submodule_dir && git commit -m "..."

Other

In order to change submodule's URL, edit .gitmodules files and run git submodule sync

Useful infographic

References

http://www.saintsjd.com/2011/01/what-is-a-bare-git-repository/
http://gitolite.com/gcs.html#%281%29