1. Open a Terminal Window if not yet in command line
  2. Type in the following command: cat /proc/meminfo
  3. This will display a resultset as below of how much memory you have left

MemTotal:        1974152 kB MemFree:          373196 kB Buffers:          107380 kB Cached:           881568 kB SwapCached:        13288 kB Active:           872248 kB Inactive:         640876 kB Active(anon):     599548 kB Inactive(anon):    25012 kB Active(file):     272700 kB Inactive(file):   615864 kB Unevictable:           8 kB Mlocked:               8 kB HighTotal:       1103016 kB HighFree:           1612 kB LowTotal:         871136 kB LowFree:          371584 kB SwapTotal:       2493588 kB SwapFree:        2461148 kB Dirty:                72 kB Writeback:             0 kB AnonPages:        514288 kB Mapped:           122972 kB Slab:              50072 kB SReclaimable:      32964 kB SUnreclaim:        17108 kB PageTables:         5136 kB NFS_Unstable:          0 kB Bounce:                0 kB WritebackTmp:          0 kB CommitLimit:     3480664 kB Committed_AS:    2313760 kB VmallocTotal:     122880 kB VmallocUsed:       23780 kB VmallocChunk:      93580 kB HugePages_Total:       0 HugePages_Free:        0 HugePages_Rsvd:        0 HugePages_Surp:        0 Hugepagesize:       4096 kB DirectMap4k:       16376 kB DirectMap4M:      888832 kB