[root@s14wefm tmp]# ruby -v
ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
[root@s14wefm tmp]# ruby prova5.rb 
Child 11473
Child response=kkkkk
Child finito ...
[root@s14wefm tmp]# ruby prova2.rb 
Parent is 11475
Parent eseguo: ruby /tmp/prova5.rb
[root@s14wefm tmp]#