Use chezmoi with Watchman

chezmoi can be used with Watchman to automatically run chezmoi apply whenever your source state changes, but there are some limitations because Watchman runs actions in the background without a terminal.

Firstly, Watchman spawns a server which runs actions when file systems change. This server reads its environment variables when it is started, typically on the first invocation of the watchman command. If you use a password manager that uses environment variables to persist login sessions, then you must login to your password manager before you run the first watchman command, and your session might eventually time out.

Secondly, Watchman runs processes without a terminal, and so cannot run interactive processes. For chezmoi apply, you can use the --force flag to suppress prompts to overwrite files that have been modified since chezmoi last wrote them. However, if any other part of chezmoi apply is interactive, for example if your password manager prompts for a password, then it will not work with Watchman.

1. Tell watchman to watch your source directory:

   CHEZMOI_SOURCE_PATH="$(chezmoi source-path)"
   watchman watch "${CHEZMOI_SOURCE_PATH}"
   

2. Tell watchman to run chezmoi apply --force whenever your source directory changes:

   watchman -j <<EOT
   ["trigger", "${CHEZMOI_SOURCE_PATH}", {
     "name": "chezmoi-apply",
     "command": ["chezmoi", "apply", "--force"]
   }]
   EOT
   

You can now make changes to your source directory and Watchman will run chezmoi apply --force on each change.

To shutdown the Watchman server, run:

```sh
watchman shutdown-server
```