Re: How to create a new commit with the content of some commit?

[Ping Yin <pkufranky@gmail.com>]

On Wed, May 13, 2009 at 12:07 AM, Jeff King <peff@peff.net> wrote:
> On Tue, May 12, 2009 at 10:35:30PM +0800, Ping Yin wrote:
>
>> a----b
>>  \----c
>>
>> Given the graph above, I want to create a commit b1 on top of c, where
>> b1 and b have the same content. i.e.
>>
>> a----b
>>  \----c----b1    ( content(b) == content(b1) )
>>
>> If there are no untracked files in the working directory, i can do
>>
>> git checkout b
>> git reset c
>> git add .
>> git commit -m "the copy of b"
>>
>> Is there any simpler way? And if there are untracked files in the
>> working directory, how to do it?
>
> You can just munge the index directly, and skip the working tree
> entirely:
>
>  rm .git/index
>  git read-tree b
>  git commit -m 'the copy of b'

In a non-conflict status, "git read-tree b" will update the index to
full match the tree of b, so "rm .git/index" is unnecessary, right?


> You can also do it without even touching the index by using the commit
> plumbing:
>
>  echo 'copy of b' >message
>  tree=`git rev-parse b^{tree}`
>  commit=`git commit-tree $tree -p c <message`
>  git update-ref c $commit

Nice solution. Thank you and thank so powerful git!

Maybe a -c option can be added to git-commit-tree?