On Thu, May 16, 2019 at 7:25 AM Duy Nguyen <pclouds@xxxxxxxxx> wrote: > pre-commit hook sets GIT_INDEX_FILE to this "index.lock" so you have > the latest index content (which is not the same as from > $GIT_DIR/index). This variable will interfere with any commands that > work on a different worktree. I think that this is not quite accurate. The problem isn't that git-commit is pointing GIT_INDEX_FILE at a temporary index; that works fine. The problem is when it is using the normal .git/index file, in which case the value it assigns to GIT_INDEX_FILE is relative. For instance, with pre-commit hook: #!/bin/sh echo "GIT_INDEX_FILE=$GIT_INDEX_FILE" git worktree add --detach other "git-worktree add" with a normal git-commit breaks due to the relative location specified by GIT_INDEX_FILE: $ git add file $ git commit -m foo GIT_INDEX_FILE=.git/index Preparing worktree (detached HEAD 0857fef) fatal: Unable to create '/.../other/.git/index.lock': Not a directory $ whereas, the "git commit <file>" form succeeds just fine because it assigns an absolute path for the temporary index: $ git commit -m foo file GIT_INDEX_FILE=/.../.git/next-index-23675.lock Preparing worktree (detached HEAD 0857fef) HEAD is now at 0857fef first [master 2fa5413] foo $