gawkworkflow: Repo Copies
2.2 How Git Stores Branches and Their Copies
============================================
So how does Git work?(1)
A repository consists of a collection of "branches". Each branch
represents the history of a collection of files and directories (a file
"tree"). Each combined set of changes to this collection (files and
directories added or deleted, and/or file contents changed) is termed a
"commit".
When you first create a local copy of a remote repository ("clone the
repo"), Git copies all of the original repository's branches to your
local system. The original remote repository is referred to as being
"upstream", and your local repo is "downstream" from it. Git
distinguishes branches from the upstream repo by prefixing their names
+======================+
| Branches |
+======================+
| master |
+----------------------+
| gawk-4.1-stable |
+----------------------+
| gawk-4.0-stable |
+----------------------+
| feature/fix-comments |
+----------------------+
| ... |
+----------------------+
Figure 2.1: The Savannah 'gawk' Repository
After you clone the repo, on your local system you will have a single
branch named 'master' that's visible when you use 'git branch' to see
your branches.
$ git clone http://git.savannah.gnu.org/r/gawk.git Clone the repo
$ cd gawk Change to local copy
$ git branch See branch information
-| * master
The current branch is always indicated with a leading asterisk ('*').
Pictorially, the local repo looks like 
Figure 2.2 your-repo.
(you can ignore the 'T' column for the moment):
+===+======================++=============================+
| T | Local Branches || Remote Branches |
+===+======================++=============================+
| X | master || origin/master |
+---+----------------------++-----------------------------+
| | || origin/gawk-4.1-stable |
+---+----------------------++-----------------------------+
| | || origin/gawk-4.0-stable |
+---+----------------------++-----------------------------+
| | || origin/feature/fix-comments |
+---+----------------------++-----------------------------+
| | || ... |
+---+----------------------++-----------------------------+
Figure 2.2: Your Local 'gawk' Repository
Note that what is simply 'gawk-4.1-stable' in the upstream repo is now
referred to as 'origin/gawk-4.1-stable'. The 'origin/' branches are a
snapshot of the state of the upstream repo. This is how Git allows you
to see what changes you've made with respect to the upstream repo,
without having to actually communicate with the upstream repo over the
Internet. (When files are identical, Git is smart enough to not have
two separate physical copies on your local disk.)
If you're working on a simple bug fix or change, you can do so
directly in your local 'master' branch. You can then commit your
changes, and if you have access rights, push them upstream to the
Savannah repo. (However, there is a process to follow. Please read the
rest of this Info file.)
---------- Footnotes ----------
(1) The following description is greatly simplified.
Info Catalog
gawkworkflow: Push Pull
gawkworkflow: Using Git
gawkworkflow: Local Branches