Use case

There is a XDG Base Directory Specification which supports keeping home directory in Linux environments tidy. Currently, flutter keeps its global configuration in $HOME/.flutter and $HOME/.flutter_tool_state. According to the above mentioned specification, it is advised to keep configuration under $HOME/.config directory by default.

Proposal

Allow user to set an environment variable to override default directory of flutter config files. This way it won't affect configuration of current users.

Alternatively, a fallback check to $HOME can be done if configuration does not exist in XDG base directory. This way XDG specification will be followed by default without having to set any environment variables.