Display total, used, and available system memory.
low risk
free shows physical memory and swap usage. The 'available' column (not 'free') is what matters — it includes reclaimable cache and is what the kernel reports as usable for new processes. Buffers and cache are not 'wasted' memory.
| Flag | Meaning |
|---|---|
-h --human | Print human-readable sizes (MB/GB) |
-s --seconds | Continuously update at interval |
-t --total | Show grand total row |
free -hShow memory usage in human-readable format · explain & risk-check →free -h -s 2Refresh memory stats every 2 seconds · explain & risk-check →free -htShow human-readable with total row · explain & risk-check →The 'available' column is the only one that matters for capacity planning — ignore 'free'. Linux aggressively uses RAM for cache; that's normal and good.
Reference text is hand-written and may be incomplete — check man free for your version. Test destructive commands on a non-production system first.