Using the execute shell command (:!) on Windows and MSYS2

Question

I'm new to neovim (and vim in general), and I'm trying to use it on Windows with MSYS2. I noticed they have a package for vim, but not for neovim. I used the neovim installed through chocolatey instead, but I couldn't get the :!{cmd} command to work. It returns "/usr/bin/bash: /s: No such file or directory". Neovim seems to work normally otherwise, including the :terminal command. Is there a way to get around this problem without changing the shell to cmd/powershell?

Answer 1

The comments by B layer and Ben Knoble were both helpful in finding the answer.

Vim correctly set the shell based on the $SHELL variable, but did not set shellcmdflag appropriately, and that was what the /s was, the default shellcmdflag for cmd.exe, as stated in the :help 'shell' file.

Setting it to -c in my init.vim seems to have solved the problem, and a similar solution found in https://www.gitmemory.com/issue/mattn/vim-lsp-settings/234/631950449 seems to indicate that it might be useful to also set the shellxquote and shellslash variables. Unlike him, I did not set my PATH or the shell variable itself as I ran neovim from within MSYS2.

I added the following to vim.init so I could still use cmd.exe if I were to run nvim externally.

if $SHELL == "C:/msys64/usr/bin/bash"
    let &shellcmdflag = '-c'
    set shellxquote=(
    set shellslash
endif