Autogenerated HTML docs for v1.6.4-122-g6ffd7

1 files changed, 73 insertions, 1 deletions

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@@ -791,6 +791,78 @@ reason
 </dd>

 </dl></div>

 </div>

+<h2 id="_note_about_fast_forwards">Note about fast-forwards</h2>

+<div class="sectionbody">

+<div class="para"><p>When an update changes a branch (or more in general, a ref) that used to

+point at commit A to point at another commit B, it is called a

+fast-forward update if and only if B is a descendant of A.</p></div>

+<div class="para"><p>In a fast-forward update from A to B, the set of commits that the original

+commit A built on top of is a subset of the commits the new commit B

+builds on top of.  Hence, it does not lose any history.</p></div>

+<div class="para"><p>In contrast, a non-fast-forward update will lose history.  For example,

+suppose you and somebody else started at the same commit X, and you built

+a history leading to commit B while the other person built a history

+leading to commit A.  The history looks like this:</p></div>

+<div class="listingblock">

+<div class="content">

+<pre><tt>

+      B

+     /

+ ---X---A

+</tt></pre>

+</div></div>

+<div class="para"><p>Further suppose that the other person already pushed changes leading to A

+back to the original repository you two obtained the original commit X.</p></div>

+<div class="para"><p>The push done by the other person updated the branch that used to point at

+commit X to point at commit A.  It is a fast-forward.</p></div>

+<div class="para"><p>But if you try to push, you will attempt to update the branch (that

+now points at A) with commit B.  This does _not_ fast-forward.  If you did

+so, the changes introduced by commit A will be lost, because everybody

+will now start building on top of B.</p></div>

+<div class="para"><p>The command by default does not allow an update that is not a fast-forward

+to prevent such loss of history.</p></div>

+<div class="para"><p>If you do not want to lose your work (history from X to B) nor the work by

+the other person (history from X to A), you would need to first fetch the

+history from the repository, create a history that contains changes done

+by both parties, and push the result back.</p></div>

+<div class="para"><p>You can perform "git pull", resolve potential conflicts, and "git push"

+the result.  A "git pull" will create a merge commit C between commits A

+and B.</p></div>

+<div class="listingblock">

+<div class="content">

+<pre><tt>

+      B---C

+     /   /

+ ---X---A

+</tt></pre>

+</div></div>

+<div class="para"><p>Updating A with the resulting merge commit will fast-forward and your

+push will be accepted.</p></div>

+<div class="para"><p>Alternatively, you can rebase your change between X and B on top of A,

+with "git pull --rebase", and push the result back.  The rebase will

+create a new commit D that builds the change between X and B on top of

+A.</p></div>

+<div class="listingblock">

+<div class="content">

+<pre><tt>

+      B   D

+     /   /

+ ---X---A

+</tt></pre>

+</div></div>

+<div class="para"><p>Again, updating A with this commit will fast-forward and your push will be

+accepted.</p></div>

+<div class="para"><p>There is another common situation where you may encounter non-fast-forward

+rejection when you try to push, and it is possible even when you are

+pushing into a repository nobody else pushes into. After you push commit

+A yourself (in the first picture in this section), replace it with "git

+commit --amend" to produce commit B, and you try to push it out, because

+forgot that you have pushed A out already. In such a case, and only if

+you are certain that nobody in the meantime fetched your earlier commit A

+(and started building on top of it), you can run "git push --force" to

+overwrite it. In other words, "git push --force" is a method reserved for

+a case where you do mean to lose history.</p></div>

+</div>

 <h2 id="_examples">Examples</h2>

 <div class="sectionbody">

 <div class="vlist"><dl>

@@ -936,7 +1008,7 @@ by Linus Torvalds &lt;torvalds@osdl.org&gt;</p></div>
 </div>

 <div id="footer">

 <div id="footer-text">

-Last updated 2009-07-09 16:48:59 UTC

+Last updated 2009-08-13 01:22:27 UTC

 </div>

 </div>

 </body>