Linux commands

Hardware#

All of these only read information. They change nothing.

The machine#

Command	Shows
`hostnamectl`	Name, Debian version, kernel, model (e.g. `MacBookPro14,1`)
`cat /etc/os-release`	Exact Debian version
`uname -r`	Kernel version
`uptime`	How long since the last restart, and the load
`sudo dmidecode -s system-product-name`	Computer model

Command	Shows
`lscpu`	Model, cores, threads, speed
`nproc`	Number of threads
`grep -o -w -m1 avx2 /proc/cpuinfo`	Prints `avx2` if the CPU has it (fast AI)
`htop`	Live CPU and memory per program (`Q` quits; `F6` sorts)
`top`	Same, always installed

Load (in uptime and htop): roughly how many threads are busy. On a 4-thread CPU, a load of 4 is "fully busy".

Command	Shows
`free -h`	Total, used and available memory, plus swap
`swapon --show`	Swap space
`vmstat 2`	Memory/CPU every 2 seconds (`Ctrl`+`C` stops)

Look at available, not "free". Linux uses spare memory as cache and gives it back when needed.

sudo apt install lm-sensors
sensors
watch -n 2 sensors       # refresh every 2 seconds, Ctrl+C stops

Command	Shows
`cat /sys/class/power_supply/ADP1/online`	`1` = charger connected
`cat /sys/class/power_supply/BAT0/status`	`Charging`, `Full`, `Discharging`
`cat /sys/class/power_supply/BAT0/capacity`	Charge in %
`ls /sys/class/power_supply/`	Names on your machine (may differ from `ADP1`/`BAT0`)

Command	Shows
`lsusb`	Everything plugged into USB
`lsusb -t`	USB speed per device: `480M` = USB 2 (slow), `5000M` = USB 3
`lspci`	Internal parts: Wi-Fi card, graphics, disk controller
`sudo dmesg -w`	Live hardware messages. Plug something in and watch (`Ctrl`+`C` stops)
`sudo dmesg \| tail -30`	The latest hardware messages

sudo apt install stress-ng
stress-ng --cpu 2 --timeout 120s

Watch sensors in another window. Stop with Ctrl+C if it goes above 90 °C.