--dry-run::
Do everything except actually send the updates.
+--porcelain::
+ Produce machine-readable output. The output status line for each ref
+ will be tab-separated and sent to stdout instead of stderr. The full
+ symbolic names of the refs will be given.
+
--tags::
All refs under `$GIT_DIR/refs/tags` are pushed, in
addition to refspecs explicitly listed on the command
<flag> <summary> <from> -> <to> (<reason>)
-------------------------------
+If --porcelain is used, then each line of the output is of the form:
+
+-------------------------------
+ <flag> \t <from>:<to> \t <summary> (<reason>)
+-------------------------------
+
flag::
A single character indicating the status of the ref. This is
blank for a successfully pushed ref, `!` for a ref that was
refs, no explanation is needed. For a failed ref, the reason for
failure is described.
+Note about fast-forwards
+------------------------
+
+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.
+
+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.
+
+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:
+
+----------------
+
+ B
+ /
+ ---X---A
+
+----------------
+
+Further suppose that the other person already pushed changes leading to A
+back to the original repository you two obtained the original commit X.
+
+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.
+
+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.
+
+The command by default does not allow an update that is not a fast-forward
+to prevent such loss of history.
+
+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.
+
+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.
+
+----------------
+
+ B---C
+ / /
+ ---X---A
+
+----------------
+
+Updating A with the resulting merge commit will fast-forward and your
+push will be accepted.
+
+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.
+
+----------------
+
+ B D
+ / /
+ ---X---A
+
+----------------
+
+Again, updating A with this commit will fast-forward and your push will be
+accepted.
+
+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.
+
+
Examples
--------