title: How to check a weston environment
body: <p>How can I, at runtime check whether the program is running in a Weston environment.
  I program a Gtk+-3.0 in C and I want depending on the Display Server technology the GUI is running different windows size and similar hints.</p>
  
  <p>To be more precise. My system is a very small embedded linux. I start weston via systemd:</p>
  
  <pre>
  # weston systemd service unit file                                                                          
  
  [Unit]
  Description=Weston launcher
  After=systemd-user-sessions.service
  
  [Service]
  Environment=PATH=/usr/bin:/bin:/usr/sbin:/sbin
  Environment=HOME=/root
  ExecStart=/root/weston.sh
  Restart=always
  RestartSec=10
  
  [Install]
  Alias=display-manager.service
  WantedBy=graphical.target
  </pre>
  
  <p>This is the startup script:</p>
  
  <pre>
  #!/bin/bash
  # Weston startup file.
  export XDG_RUNTIME_DIR="/run/shm/wayland"
  mkdir -p "$XDG_RUNTIME_DIR"
  chmod 0700 "$XDG_RUNTIME_DIR"
  
  /usr/bin/weston --tty=1 --log=/var/log/weston.log
  </pre>