Git subdirectory filter with existing directory st

Question

I'm splitting out a Git repository using the --subdirectory-filter option of filter-branch which is working great except it pulls everything up to the root of the repository.

I currently have

ABC
  - DEF
      - GHI
      - JKL
  - MNO

And the result of this command:

git filter-branch -f --subdirectory-filter ABC/DEF --prune-empty -- --all

Generates this:

GHI
JKL

Where what I really want is this:

ABC
  - DEF
      - GHI
      - JKL

I can't see anything in the Git docs that shows a filter option which preserves (or sets) the directory structure and I haven't been able to find a command I can run after the filtering to remap the structure to how I want it.

Is this possible?

Answer 1

I found an answer here which does the trick.

The command:

git filter-branch -f --index-filter 'git ls-files -s \
| sed "s-\t-&ABC/DEF/-" \
| GIT_INDEX_FILE=$GIT_INDEX_FILE.new git update-index --index-info \
&& mv $GIT_INDEX_FILE.new $GIT_INDEX_FILE'

works perfectly

Answer 2

I've only given this cursory testing myself, but I think you can use git filter-branch with --tree-filter to rewrite the branch, but removing all files apart from those in the subdirectory ABC/DEF, with something like the following:

git filter-branch --tree-filter \
    'find . -path ./ABC/DEF -prune -o -type f -print0 | xargs -0 rm -f' \
    --prune-empty HEAD

Note that the find command only removes files, not directories, but since git doesn't store empty directories, this should still produce the result you want.