git-filter-branch with --index-filter : strange bash error ( ! : event not found)

Question

I am using the answer to this question to strip a clone of a repository to a list of files I want to keep in a spin off of this project. Say I want to strip all but directory src/main and its sub-directories. Because I will have multiple files and directories, I use --index-filter instead of --subdirectory-filter.

I thought the following should work:

git filter-branch --index-filter "git rm -r -f --cached --ignore-unmatch ↩
  src/!(main)" --prune-empty -- --all

But all I get is

-bash: !: event not found

I tried all sorts of different paths instead of src/!(main). I always get exactly that error message. It seems to be a bash problem, because that line also doesn't enter my command line history?

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That is to say, if I have top level files A, and B, and subdirectory C/D, how can I remove all but these three things?

Answer 1

The ! is the issue, since it is used for command history recall. Inside quotes, putting a backslash in front does not help either, so the \! must be outside quotes. Can be illustrated using a few examples with echo:

/home/user1> echo "src/!(main)"
-bash: !: event not found
/home/user1> echo "src/\!(main)"
src/\!(main)
/home/user1> echo "src/"\!"(main)"
src/!(main)

Answer 2

To answer the the actual question added in the clarification: you're trying to use bash's extglob to remove everything in src but main in a git index-filter. This doesn't work because the index-filter command is not executed by your shell, but by sh via eval (see /usr/lib/git-core/git-filter-branch:327).

You can't tell git to enable extglob when doing this, but you can make your shell expand the extglob before passing it to index-filter:

git filter-branch --index-filter "git rm -r -f --cached --ignore-unmatch $(ls -xd src/!(main))" --prune-empty -- --all

Answer 3

The exclamation point is used in Bash's syntax to do history expansion, which is what causes the confusion. You must escape it using backslash or single quotes:

git filter-branch --index-filter "git rm -r -f --cached --ignore-unmatch ↩
  src/\!(main)" --prune-empty -- --all