valid, though.
[NOTE]
-An 'object' is identified by its 160-bit SHA1 hash, aka 'object name',
+An 'object' is identified by its 160-bit SHA-1 hash, aka 'object name',
and a reference to an object is always the 40-byte hex
-representation of that SHA1 name. The files in the `refs`
+representation of that SHA-1 name. The files in the `refs`
subdirectory are expected to contain these hex references
(usually with a final `\n` at the end), and you should thus
expect to see a number of 41-byte files containing these
In fact, together with the 'git rev-list' program (which generates a
list of revisions), 'git diff-tree' ends up being a veritable fount of
-changes. A trivial (but very useful) script called 'git whatchanged' is
-included with Git which does exactly this, and shows a log of recent
-activities.
-
-To see the whole history of our pitiful little git-tutorial project, you
-can do
-
-----------------
-$ git log
-----------------
-
-which shows just the log messages, or if we want to see the log together
-with the associated patches use the more complex (and much more
-powerful)
-
-----------------
-$ git whatchanged -p
-----------------
-
-and you will see exactly what has changed in the repository over its
-short history.
-
-[NOTE]
-When using the above two commands, the initial commit will be shown.
-If this is a problem because it is huge, you can hide it by setting
-the log.showroot configuration variable to false. Having this, you
-can still show it for each command just adding the `--root` option,
-which is a flag for 'git diff-tree' accepted by both commands.
-
-With that, you should now be having some inkling of what Git does, and
-can explore on your own.
-
-[NOTE]
-Most likely, you are not directly using the core
-Git Plumbing commands, but using Porcelain such as 'git add', `git-rm'
-and `git-commit'.
+changes. You can emulate `git log`, `git log -p`, etc. with a trivial
+script that pipes the output of `git rev-list` to `git diff-tree --stdin`,
+which was exactly how early versions of `git log` were implemented.
Tagging a version
these object pointers.
You can at any time create a new branch by just picking an arbitrary
-point in the project history, and just writing the SHA1 name of that
+point in the project history, and just writing the SHA-1 name of that
object into a file under `.git/refs/heads/`. You can use any filename you
want (and indeed, subdirectories), but the convention is that the
"normal" branch is called `master`. That's just a convention, though,
etc.). After reading three trees into three stages, the paths
that are the same in all three stages are 'collapsed' into stage
0. Also paths that are the same in two of three stages are
-collapsed into stage 0, taking the SHA1 from either stage 2 or
+collapsed into stage 0, taking the SHA-1 from either stage 2 or
stage 3, whichever is different from stage 1 (i.e. only one side
changed from the common ancestor).