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

[Ondra Medek <xmedeko@gmail.com>]

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
> >