How to create keyboard shortcut which initiates suspend

I tested the command mentioned here on Gnome 15.04, and it did the job well. The next thing to do is then to make it available under a shortcut key.

The easiest way would be to create a small script of it:

#!/bin/bash

dbus-send --system --print-reply \
  --dest="org.freedesktop.login1" \
  /org/freedesktop/login1 \
  org.freedesktop.login1.Manager.Suspend boolean:true

save it as initiate_suspend.sh, and make it available under a shortcut key. To do that works the same in Gnome as it works in Unity: choose: System Settings > "Keyboard" > "Shortcuts" > "Custom Shortcuts". Click the "+" and add the command:

/bin/bash /path/to/initiate_suspend.sh

to a shortcut key combination of your choice.