#ref: https://etherlab.org/en/ethercat/index.php
sudo apt-get install linux-headers-($uname -r) 
sudo apt-get install udev autoconf libtool geany

# I usually do this in a folder called ~/devel
cd ~
mkdir devel
cd devel
git clone https://gitlab.com/etherlab.org/ethercat.git
cd ethercat
git checkout stable-1.5
#ref: https://gitlab.com/etherlab.org/ethercat/-/blob/master/INSTALL.md
./bootstrap
./configure --sysconfdir=/etc  --enable-8139too=no
make all modules
sudo make modules_install install
sudo depmod

#ref: sticky - https://forum.linuxcnc.org/ethercat/45336-ethercat-installation-from-repositories-how-to-step-by-step?start=0
sudo geany /etc/ethercat.conf
sudo geany /etc/udev/rules.d/99-ethercat.rules
#paste in: KERNEL=="EtherCAT[0-9]", MODE="0777"
#save and exit
sudo udevadm control --reload-rules
systemctl start ethercat 
sudo systemctl enable ethercat.service
sudo systemctl start ethercat.service
sudo systemctl status ethercat.service
sudo chmod 666 /dev/EtherCAT0