How can I create a commit without a parent?

How can I create a commit without a parent?

[Ron Garret]

SLSIA.  git commit-tree insists on having at least one parent commit at 
the command line.  From reverse-engineering it seems like I could do it 
by setting .git/HEAD to 'ref: refs/heads/some-nonexistent-branch' but 
mucking with HEAD directly like that feels kinda scary.

Thanks,
rg

Re: How can I create a commit without a parent?

[Junio C Hamano]

Ron Garret <ron1@flownet.com> writes:

> git commit-tree insists on having at least one parent commit at 
> the command line.

Incorrect.  "git commit" might but "git commit-tree" does.  Perhaps you
are forgetting that the first object name is a tree to be wrapped.

A short answer is that you don't create a root commit twice in a single
repository, period.  Your repository _may_ be end up with more than one
root but that typically is due to you fetching unrelated histories from
different repositories, each created its own root.

Re: How can I create a commit without a parent?

[Ron Garret]

In article <7vwryw6p16.fsf@alter.siamese.dyndns.org>,
 Junio C Hamano <gitster@pobox.com> wrote:

> Ron Garret <ron1@flownet.com> writes:
> 
> > git commit-tree insists on having at least one parent commit at 
> > the command line.
> 
> Incorrect.  "git commit" might but "git commit-tree" does.  Perhaps you
> are forgetting that the first object name is a tree to be wrapped.

No, I didn't forget that.  I forgot to omit the -p flag.  Doh!

> A short answer is that you don't create a root commit twice in a single
> repository, period.

Why not?  I could easily create an empty root commit and multiple 
branches off that.  (Maybe that's a better way to go.)  What would be 
the difference?

rg

Re: How can I create a commit without a parent?

[Jakub Narebski]

Ron Garret <ron1@flownet.com> writes:

> SLSIA.  git commit-tree insists on having at least one parent commit at 
> the command line.  From reverse-engineering it seems like I could do it 
> by setting .git/HEAD to 'ref: refs/heads/some-nonexistent-branch' but 
> mucking with HEAD directly like that feels kinda scary.

You have git-symbolic-ref to set HEAD directly (don't forget to remove
index).  

Or you can set up / initialize separate (new) repository, create
commit there and then pull this new repository into current one.


P.S. Creating new root (parentless) commit isn't something that you do
on purpose, usually.

-- 
Jakub Narebski
Poland
ShadeHawk on #git

Re: How can I create a commit without a parent?

[Jay Soffian]

On Tue, Feb 2, 2010 at 3:00 AM, Ron Garret <ron1@flownet.com> wrote:
> SLSIA.  git commit-tree insists on having at least one parent commit at
> the command line.  From reverse-engineering it seems like I could do it
> by setting .git/HEAD to 'ref: refs/heads/some-nonexistent-branch' but
> mucking with HEAD directly like that feels kinda scary.

I guess you're looking to do it with plumbing, but with porcelain the
way I'd do it is:

$ git init foo
$ git init bar
$ cd bar
$ git commit --allow-empty -m "empty bar root commit"
$ cd ../foo
$ git commit --allow-empty -m "empty foo root commit"
$ git fetch ../bar master:bar

j.