Re: Any way to "flatten" a series of changes in git

[Howard Miller <howard@e-learndesign.co.uk>]

2009/10/22 Jakub Narebski <jnareb@gmail.com>:
> On Thu, 22 Oct 2009, Howard Miller wrote:
>
>> > You can use either "git merge --squash" or "git rebase --interactive"
>> > (changing 'pick' to 'squash').
>> >
>>
>> Actually thinking some more.... I don't understand something about
>> this. I don't actually want to merge or rebase with anything. I just
>> want to say "make those commits a series of commits on a branch into
>> just one commit with a new message". I seriously suspect I'm missing
>> the point somewhere but what has that got to do with merging or
>> rebasing?
>
> Actually using "git merge --squash" is a bit different from using
> "git rebase --interactive".
>
>
> 1. "git merge --squash"
>
> From documentation:
>
>  --squash::
>        Produce the working tree and index state as if a real
>        merge happened (except for the merge information),
>        but do not actually make a commit or
>        move the `HEAD`, nor record `$GIT_DIR/MERGE_HEAD` to
>        cause the next `git commit` command to create a merge
>        commit.  This allows you to create a single commit on
>        top of the current branch whose effect is the same as
>        merging another branch (or more in case of an octopus).
>
> This means for example if you did your changes on a separate
> topic branch, and you want to merge your changes into 'master'
> branch, you would do
>
>  $ git checkout master
>  $ git merge side-branch
>
> which would result in the following history:
>
>
>   ---*---*---*---*---*---*---*---M         <-- master
>       \                         /
>        \-.---.---.---.---.---.-/           <-- side-branch
>
>
> If you used '--squash' option to git-merge, because changes were
> made in throwaway topic branch, and as you said only final result
> matter, you would get:
>
>  $ git checkout master
>  $ git merge --squash side-branch
>
>   ---*---*---*---*---*---*---*---M'        <-- master
>       \
>        \-.---.---.---.---.---.             <-- side-branch
>
>
> where commit M' has the same contents (the same tree) as commit M
> in previous example, but is not a merge commit.
>
> If you simply want to squash last say 5 commits into one, you can
> use "git merge --squash" for it in the following way:
>
>  $ git reset --hard HEAD~5
>  $ git merge --squash --no-ff HEAD@{1}
>
> which means basically: rewind to state 5 commits back, then merge
> in changes from before rewind, squashing them.  The --no-ff is needed
> because otherwise it would be fast-forward and no commit would be
> created.
>
>
> 2. "git rebase --interactive"
>
> The interactive rebase is meant to edit commits being rebased, but
> it can be used simply to edit commits.  It includes 'squash' command
> that can be used to concatenate (squash) commits.
>
> So to squash last say 5 commits into one, you would use
>
>  $ git rebase --interactive HEAD~5
>
> then edit provided list of commands and commits to read something like
> this:
>
>   pick deadbee The oneline of this commit
>   squash fa1afe1 The oneline of the next commit
>   ...
>   squash beedead The oneline of the that commit
>
> i.e. replace 'pick' command by 'squash' command.
>
> This is a very powerfull command, and can be used for example to turn
> series of say 5 commits into series of say 2 commits; not simply squashing
> to a single commit, but reducing number of commits (and presumably
> cleaning up those commits).
>
>
> HTH (hope that helps)
> --
> Jakub Narebski
> Poland
>

Hi Jakub,

Yes it helps a lot. What I *don't* care about (or want to do) is
actually do a merge or a rebase I just want to change history. Well,
that's what I thought I wanted. What I suppose I really want is the
full history for *me* and a second branch with the 'reduced' history
to push to my client.  I suppose that's different yet again?

Howard