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

[Ondra Medek <xmedeko@gmail.com>]

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

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
> > >