opts.banner+="This script looks for file ~/.grid5000_api.yml containing your API username and password credentials. The script also recognize API_USER and API_PASSWORD environment variables."
opts.on('-g','--generators=generator1,generator2',Array,'Run those generators')do|g|
options[:generators]=g
end
opts.on('-s','--sites=site1,site2',Array,'Only consider these sites (when applicable)')do|sites|