Linux查看内存使用量和交换区使用量

youhaidong@youhaidong-ThinkPad-Edge-E545:~$ free -m
             total       used       free     shared    buffers     cached
Mem:          3030       1690       1339          8         66        683
-/+ buffers/cache:        941       2089
Swap:         3904          0       3904
youhaidong@youhaidong-ThinkPad-Edge-E545:~$ free --mega
             total       used       free     shared    buffers     cached
Mem:          3030       1691       1339          8         66        683
-/+ buffers/cache:        941       2088
Swap:         3904          0       3904