branch

You are always in a branch in git.  The branch created with git init command is called 'master'.

You can have multiple branches.  To show all the branches, use git branch.  You can switch to a different branch by git checkout command.

To create a new branch, use git branch branchname.

git checkout -b branchname is a shortcut to create a new branch and switch to it.

git branch -d branchname will delete a specified branch.

What is HEAD?
HEAD is the special symbol to refer the current branch.  A Branch is referred by a head, which is the tip of a branch.

To see which branch you're using, use git branch.

branch and file modification
When you modify a file in a branch and haven't commited, you cannot switch to a different branch.

Also, file you created will be carried to a branch you switched.

Revert

git revert is used for a different meaning than other version control systems such as svn.

Revert to the last committed state
--hard changes the working tree and index.

Revert a single file to the repository version

git setup for Rails project

Create .gitignore file with following content:
If you already committed some of these files, remove them using git rm.

Initialize a repository

This commands create a git repository at target/.git.

.git/config - configuration file for the repository.
.git/description - a file used by gitweb utility.

The git index is used as a staging area between a working directory and a git repository.

Files in "Changed but not updated" is not in the index.

Show the list of remote git repositories

It shows the list of the remote repository names.

To see more details, use -v

Pull a specific version of a file with git

git checkout commit path
I got the commit name with git log command.

Is .gitignore not working?

Even though I have the following line in .gitignore file, changes are showing up in git status.

.gitignore doesn't have effect to already tracked files.  Remove it from repository (git rm ...) or use git update-index --assume-unchanged.
(2009/06/25)