Before using this example, you need to do the following modifications in the
script called my_ssh:
- set the value of the local_dir variable to the root project dir on your
  local machine. Note that the directory must be exactly the same as the
  one used by GPS when it invokes gnatmake
- set the value of the remote_dir variable to the root project dir on your
  remote machine

In GPS, you need to set the field "Project -> Edit Project Properties 
-> General -> Tools Host" to your remote machine name and the
"Edit -> Preferences -> External Command -> Remote Shell" field to 
"bash /directory/my_ssh".