Limit cpu usage when running a command (i.e. cgroup interface for

limit_cpu.sh

systemd-run --user --scope -p CPUQuota=25% --slice=stress -- stress -c 1
# Where you replace stress -c 1 with your command 

# Ubuntu 20.04 doesn't support this with non root users, so you have to run 
sudo systemd-run --scope -p CPUQuota=25% --slice=stress -- stress -c 1
# Note that this remove all the environment variables.

# If you want to run as the current user
sudo systemd-run --scope -p CPUQuota=25% --uid="$(id -u)" --gid="$(id -g)" --slice=stress -- id

# Dynamically change limits:
systemctl set-property stress.slice CPUQuota=5%
systemctl set-property stress.slice AllowedCPUs=0,1

# Note: you can kill the entire group like:
sudo systemctl stop stress.slice