From the machines tab its hard to differenciate desktop Linux installs from
server Linux installs. Transmitting this information should make this
determination a lot easier.
Due to the reality that tailscaled is likely a system process, the standard
checks based on XDG_SESSION_TYPE or DISPLAY environment variables are not
possible (those variables won't be set). Instead, we look for listening
unix sockets that are typical of desktop installs.
Signed-off-by: Tom DNetto <tom@tailscale.com>
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