free
Overview
free displays RAM and swap usage. On modern Linux, available is more meaningful than free alone (includes reclaimable cache).
Syntax
free [options]Common Options
| Option | Description |
|---|---|
-h |
Human units |
-m / -g |
MiB / GiB |
-s N |
Refresh every N seconds |
-t |
Totals line |
-w |
Wide |
-v |
Version |
Examples with Explanations
free -h
free -m
free -h -s 2
watch -n 1 free -hInterpreting
- buff/cache — can usually be reclaimed for apps
- available — estimate for new workloads without swapping
- swap used rising under load → memory pressure
# quick pressure signal
free -h | awk '/Mem:/ {print "avail",$7} /Swap:/ {print "swap used",$3}'