Update tmux command

Author: AgenttiX

ssh/config.d/csc.conf

@@ -6,7 +6,7 @@ Host lumi mahti puhti
     PasswordAuthentication no
     ForwardX11 yes
     RequestTTY yes
-    RemoteCommand tmux new -A -s ssh \; setenv SSH_AUTH_SOCK $SSH_AUTH_SOCK
+    RemoteCommand tmux has-session && tmux set-environment SSH_AUTH_SOCK "$SSH_AUTH_SOCK" \; attach-session || tmux new-session
 
 Host lumi
     HostName lumi.csc.fi