Re: Checkout to different directory at certain commit without changing index

[phillip.wood123@gmail.com]

Hi Ondra

On 14/05/2024 07:29, Ondra Medek wrote:
> Hi Phillip,
> 
> your trick with different index file works with git checkout, too, e.g.
> 
> GIT_INDEX_FILE="$destdir"/.git git --work-tree="$destdir" checkout -f
> -q "$commit" -- ./
> rm -f "$destdir"/.git

I'd not thought of that, presumably "git restore" would work as well. 
Using "./" means it will only work from the repository root, you can use 
the pathmagic ":/" instead to checkout everything when it is run from a 
subdirectory  but you need to make sure GIT_INDEX_FILE is an absolute path.

Best Wishes

Phillip

> Sincerely
> Ondra
> 
> On Mon, 13 May 2024 at 19:23, Ondra Medek <xmedeko@gmail.com> wrote:
>>
>> Hi Phillip,
>>
>> besides dependency on tar, I do not want to use git-archive because
>> it's influenced by export-ignore and export-subst attributes, too (as
>> I have mentioned).
>>
>> Thanks for git read-tree, seems it's exactly what I need. Just git
>> read-tree has complained that -u switch needs -m or --reset switches.
>> And I have simplified it to
>>
>> git --work-tree="$destdir" read-tree --index-output="$destdir".git -u
>> --reset "$commit"
>> rm -f "$destdir"/.git
>>
>> May I post this solution to the SO thread I have mentioned?
>>
>> Thanks very much
>>
>> Ondra
>>
>> On Mon, 13 May 2024 at 17:28, Phillip Wood <phillip.wood123@gmail.com> wrote:
>>>
>>> Hi Ondra
>>>
>>> On 13/05/2024 08:26, Ondra Medek wrote:
>>>> Hello,
>>>> I need a simple script for unskilled users to do a fast checkout (LFS
>>>> friendly) of the current local Git clone at a certain commit to a
>>>> different directory I.e. something like "copy at a point in history".
>>>
>>> I think using
>>>
>>>       git archive "$commit" --format=tar |
>>>          { cd "$output_directory" && tar -xf -; }
>>>
>>> is probably the simplest solution. If you don't want to rely on tar then
>>> something like
>>>
>>>       GIT_DIR="$(git rev-parse --path-format=absolute --git-dir)" &&
>>>       GIT_COMMON_DIR="$(git rev-parse --path-format=absolute
>>> --git-common-dir)" || exit
>>>       GIT_INDEX_FILE="$GIT_DIR/tmp-index-$$"
>>>       export GIT_DIR GIT_COMMON_DIR GIT_INDEX_FILE
>>>       unset GIT_WORK_TREE
>>>       mkdir "$output_directory" && cd "$output_directory" &&
>>>       git read-tree -u "$commit"
>>>       status=$?
>>>       rm "$GIT_INDEX_FILE"
>>>       exit $status
>>>
>>> Which uses a temporary index file should work (note I haven't tested
>>> it). You may want to add "--recurse-submodules" and/or
>>> "--no-sparse-checkout" to the "git read-tree" commandline.
>>>
>>> Best Wishes
>>>
>>> Phillip
>>>
>>>> IMO all possible solutions are summarized in this thread
>>>> https://stackoverflow.com/questions/160608/do-a-git-export-like-svn-export
>>>> I describe some of them with my remarks:
>>>>
>>>> - git checkout-index : works with HEAD only.
>>>> - git archive: influenced by export-ignore and export-subst
>>>> attributes, so may not produce exact copy of sources. (And needs tar).
>>>> - git worktree add -d : needs cleanup: git prune or git remove.
>>>> - git clone: Unfortunately, -b param cannot work with commit hash and
>>>> does not respect local worktree settings (e.g. autocrlf). So, a
>>>> solution may be a bit complicated: git clone -s -n . dest/path ; cp
>>>> .git/config dest/path/.git ; cd dest/path ; git co -q <commit-ish> ;
>>>> rm -rf .git
>>>> - git checkout: Unfortunately, modifies Git index, so some action to
>>>> revert index is necessary after: git --work-tree=/path/to/checkout/
>>>> checkout -f -q <tree-ish> -- ./
>>>>
>>>> For me, the best solution is with git clone, because it does not
>>>> modify Git index nor any source working tree settings, so no cleanup
>>>> is necessary. But it's a bit complicated, though. It seems to me that
>>>> "git checkout" could do this better and simpler if it would have some
>>>> param to not modify the Git index. Is it possible to enhance git
>>>> checkout? Or is there any other simple solution not mentioned in the
>>>> SO thread?
>>>>
>>>> Thank you
>>>> Ondra Medek
>>>>