If you switched to the master channel and set the environment variable as described in the article. You should have your OS in the output of flutter devices.

Thanks for your reply.

When I type flutter channel master I get what appears to be a git pull from github.com/flutter/flutter and then these are the last lines in the output:

git: Please commit your changes or stash them before you switch branches. git: Aborting Switching channels failed with error code 1.

Is there some directory that we must be in that your article does not mention? I am new to Flutter so I don't know anything about its directory layout or any other aspects of Flutter, but I am very interested in something to build cross-platform desktop apps besides Electron.