Optional setup

Everything works without setup. Three things need a step on some machines, and tuxctl --check shows which apply to yours: it lists the sensors tuxctl finds, with their values and where they come from, and says what would enable the missing ones.

tuxctl itself never changes the system and asks for no privileges; each step below is one you take yourself, and each can be undone.

SATA and SAS disk temperatures

These need the kernel’s drivetemp module, which ships with the kernel but is usually not loaded. To load it now and at every boot:

sudo modprobe drivetemp
echo drivetemp | sudo tee /etc/modules-load.d/drivetemp.conf

Restart tuxctl afterwards: it looks for sensors at startup. To undo, delete /etc/modules-load.d/drivetemp.conf.

Hard disks: per the kernel documentation, reading the temperature may reset the spin-down timer on some drives (observed with WD120EFAX). tuxctl reads it every 2 seconds, so such a drive would never spin down. SSDs do not spin, so this does not concern them. If you rely on hard disks spinning down, leave drivetemp unloaded.

CPU power

Intel and AMD CPUs report their package energy through RAPL (/sys/class/powercap/intel-rapl:N/energy_uj), but since Linux 5.10 only root can read it: unprivileged access allowed a side-channel attack on the CPU (PLATYPUS, CVE-2020-8694). tuxctl shows the package power when the counter is readable, computed from the energy used between two readings 2 seconds apart, and nothing otherwise. The out-of-tree zenpower driver (AMD Zen 1–3) reports power directly and needs no step.

To make only the energy counters readable, now and at every boot:

echo 'ACTION=="add", SUBSYSTEM=="powercap", KERNEL=="intel-rapl:[0-9]*", RUN+="/usr/bin/chmod a+r /sys%p/energy_uj"' | sudo tee /etc/udev/rules.d/90-rapl-energy.rules
sudo udevadm trigger --subsystem-match=powercap --action=add

Restart tuxctl afterwards. This lets every local user read the energy counters again, and so reopens that side channel; weigh it on a shared machine. To undo, delete the rule and reboot.

Some monitors are instead installed with the cap_dac_read_search capability, which lets them read every file on the system regardless of its permissions; tuxctl does not need or recommend that.

NVIDIA GPUs

GPUs on NVIDIA’s proprietary driver report through NVML, which tuxctl loads at run time. The static release binaries cannot load it; use a glibc build instead. On x86_64 that can be the release’s tuxctl-x86_64-unknown-linux-gnu.tar.gz (glibc 2.28 or newer; see Installation); anywhere, a build from source:

cargo install tuxctl --locked

NVML adds about 20 MiB of memory and some CPU time; see NVIDIA GPUs on the proprietary driver for the figures, and --no-nvidia-temperature to leave it unloaded.