select name,value/(1024*1024*1024) from v$sga;

Fixed Size	        0,00206200033426285
Variable Size	       19,2500017508864
Database Buffers	6,5
Redo Buffers	        0,132972717285156


free -g

                           total       used       free     shared    buffers     cached
Mem:                      35            15         19          0          0         11
-/+ buffers/cache:                       3         31
Swap:                     37             0         37