次のように、free、cat /proc/meminfo 等、いろいろな方法がある（以下は、Amazon EC2 スモールインスタンスの例）。
# free
total used free shared buffers cached
Mem: 1747764 1733596 14168 0 109416 1162984
-/+ buffers/cache: 461196 1286568
Swap: 917496 128 917368# cat /proc/meminfo
MemTotal: 1747764 kB
MemFree: 18916 kB
Buffers: 109608 kB
Cached: 1157404 kB
SwapCached: 0 kB
Active: 1242560 kB
Inactive: 406980 kB
HighTotal: 1003528 kB
HighFree: 5156 kB
LowTotal: 744236 kB
LowFree: 13760 kB
SwapTotal: 917496 kB
SwapFree: 917368 kB
Dirty: 116 kB
Writeback: 0 kB
AnonPages: 382528 kB
Mapped: 62420 kB
Slab: 39188 kB
SReclaimable: 24684 kB
SUnreclaim: 14504 kB
PageTables: 5344 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 1791376 kB
Committed_AS: 722640 kB
VmallocTotal: 114680 kB
VmallocUsed: 1496 kB
VmallocChunk: 112984 kB# dmesg | grep Mem （システム起動時のメモリ状態）
HighMem 186366 -> 437248
HighMem zone: 1960 pages used for memmap
HighMem zone: 248922 pages, LIFO batch:31
Memory: 1711020k/1748992k available (2071k kernel code, 28636k reserved, 1080k data, 188k init, 1003528k highmem)