sar
Overview
sar (System Activity Reporter, sysstat) prints historical and live metrics: CPU, memory, disk, network, load. Data is collected by sysstat/sadc cron or systemd timers when enabled.
Syntax
sar [options] [interval [count]]
sar [options] -f /var/log/sysstat/saDDCommon Options
| Option | Description |
|---|---|
-u |
CPU (default) |
-r |
Memory |
-q |
Load / run queue |
-b |
I/O rates |
-d |
Per-block device |
-n DEV\|TCP\|… |
Network |
-s / -e |
Start/end time |
-f file |
Read data file |
-A |
Almost all |
Examples with Explanations
Live CPU samples
sar -u 1 5Memory / load
sar -r 1 5
sar -q 1 5Network devices
sar -n DEV 1 5Today’s history (if collected)
sar -u
sar -r -s 09:00:00 -e 10:00:00
ls /var/log/sysstat/Enable collection (Ubuntu sketch)
sudo apt install sysstat
# set ENABLED="true" in /etc/default/sysstat (Debian/Ubuntu)
sudo systemctl enable --now sysstat