git-rebase: document ack

document ack! behaviour and use

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 40 insertions, 5 deletions

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 2a93c645bd..c27aef470f 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -384,7 +384,7 @@ or by giving more than one `--exec`:
 +
 If `--autosquash` is used, "exec" lines will not be appended for
 the intermediate commits, and will only appear at the end of each
-squash/fixup series.
+squash/fixup/ack series.
 
 --root::
 	Rebase all commits reachable from <branch>, instead of
@@ -398,13 +398,13 @@ squash/fixup series.
 
 --autosquash::
 --no-autosquash::
-	When the commit log message begins with "squash! ..." (or
-	"fixup! ..."), and there is a commit whose title begins with
+	When the commit log message begins with "squash! ..." ("fixup! ..."
+	or "ack! ..."), and there is a commit whose title begins with
 	the same ..., automatically modify the todo list of rebase -i
 	so that the commit marked for squashing comes right after the
 	commit to be modified, and change the action of the moved
-	commit from `pick` to `squash` (or `fixup`).  Ignores subsequent
-	"fixup! " or "squash! " after the first, in case you referred to an
+	commit from `pick` to `squash` (`fixup` or `ack`).  Ignores subsequent
+	"ack! ", "fixup! " or "squash! " after the first, in case you referred to an
 	earlier fixup/squash with `git commit --fixup/--squash`.
 +
 This option is only valid when the '--interactive' option is used.
@@ -624,6 +624,41 @@ consistent (they compile, pass the testsuite, etc.) you should use
 'git stash' to stash away the not-yet-committed changes
 after each commit, test, and amend the commit if fixes are necessary.
 
+----------------
+RECORDING ACKS
+----------------
+
+Interactive mode with --autosquash can be used to concatenate
+commit log for several commits, which is useful to record
+extra information about the commit, such as ack signatures.
+This allows, for example, the following workflow:
+
+1. receive patches by mail and commit
+2. receive by mail ack signatures for the patches
+3. prepare a series for submission
+4. submit
+
+where point 2. consists of several instances of
+	i) create a (possibly empty) commit with signature
+	  in the commit message
+
+Sometimes the ack signature added in i. cannot be amended to the
+commit it acks, because that commit is buried deeply in a
+patch series.  That is exactly what rebase --autosquash
+option is for: use it
+after plenty of "i"s, to automaticlly rearrange
+commits, and squashing multiple sign-off commits into
+the commit that is signed.
+
+Start it with the last commit you want to retain as-is:
+
+	git rebase --autosquash -i <after-this-commit>
+
+An editor will be fired up with all the commits in your current branch
+which come after the given commit. Ack commits will be
+re-arranged to come after the commit that is acked,
+and the action will be utomticlly changed from `pick` to `ack`
+to cause them to be squashed into the acked commit.
 
 RECOVERING FROM UPSTREAM REBASE
 -------------------------------