ITEC 325 2013spring ibarland

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lect11a-git
version control
git

Version control provides (a) ways for multiple team members to work on the same file in parallel, and (b) ways to revert to a previous version — either of a single file, or an entire project. There are many programs out there to help with this; we'll look at “git” — only basic usage, and only one workflow (centralized repository).

Using git

• One time setup (project leader) — create a new repository from existing files
  • Your team leader can go to github.com, and create a new account. (Note that all files will be public, if you use their free version. For private repositories that are still free, see bitbucket.org.)
  • From the account web page, click “Create a new repo” (github: icon in upper right; bitbucket: “Create” button on top). (On github, check the box “create a readme”, so you can clone it immediately.)
  • Clone the (empty) repository to your own machine. You'll run “git clone …” on your own machine. The exact repository name is on the website (bitbucket: click on the “clone” button, to auto-generate this string. On github, this string is on the project's home page.)

    For example:
    git clone https://github.com/ibarland/sample-project.git
    or
    git clone https://ru-itec325-2013spring@bitbucket.org/ru-itec325-2013spring/sample.git
    

    This creates an (empty) directory on your local machine. Well, not quite empty; ls .git/ is a hidden directory full of administrative info.

  • Populate existing files into that repository.
  • git show and git status, just for fun.
  • git add .
  • git commit
  • git push
  (Note that the last three steps are all part of the standard workflow, below.)
• One-time setup (project members) — cloning an existing repository This is pretty painless: use git clone locally, to clone the central repository: git clone git@github.com:ibarland/sample-project.git This will create a directory sample-project, inside the current directory.

  Also, you can set your username and email as specified in tutorials (below).

• A common workflow:
  1. cd to working directory
  2. git pull (precautionary)
  3. [make changes; use git add for any new files]
  4. git commit -a
  5. git pull (precautionary)
  6. git push

  Both of the “git pull”s are precautionary -- just to make sure you have the most recent version before making changes.

  The reason you need to use “git add” to add new files to the repo is that IRL, you often have generated/derived files (.class) and temp files (auto-backups by your editor, say) that may be new, but are not supposed to be part of the repo.
  You can use git status to see a list of files that are new, but not part of the repo. See tutorials for ways to tell git about file-suffixes to auto-ignore, etc..

Of the many git tutorials, the one I liked best myself: book.git-scm.com/ (I've only gone through the “basic usage” section, and that seems fine; you can ignore the sections on branching/merging as we won't be doing that.)

Apparently there is a tool “gource” which produced an animation of a git repository. (Here's one example output and this alternate presentation).

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©2012, Ian Barland, Radford University Last modified 2013.Apr.15 (Mon)

Please mail any suggestions (incl. typos, broken links) to ibarlandradford.edu