• Get raspbian image (typically a ZIP from https://www.raspberrypi.org/downloads/raspbian)
• Unzip image, write to SD card:

  dd if=raspbiandownload.img of=/dev/sdX bs=4M conv=fsync

• Change root and pi passwords
• Add user, ensure groups, and sudoers
• Update host name in:
  • /etc/hostname
  • /etc/hosts
• Resize root partition, reboot, resize fs
• Make a copy of /var to /home/sys
• Install (via apt-get) some basics:
  • ksh
  • rsync
  • xterm
  • htop
  • git
  • libudev-dev
  • libusb-1.0-0-dev
  • libfox-1.6-dev
  • autotools-dev
  • autoconf
  • automake
  • libtool
  • xfe (optional)
• Prune /home/sys/var
• Set up tmpfs mounts, like (pay attention to mode and size):
  tmpfs /var/log tmpfs defaults,noatime,nosuid,mode=0755,size=100m 0 0
  • /tmp, no mode, size=100M
  • /var/tmp, no mode, size=30M
  • /var/log, mode=0755, size=100M
  • /var/spool/mqueue, mode=700, gid=12, size=30M
• Clone source for USB relay control:

  git clone git://github.com/signal11/hidapi.git
  git clone https://github.com/darrylb123/usbrelay.git

• Build HIDAPI, cd to source dir and:

  ./bootstrap
  ./configure --prefix=/usr --enable-testgui
  make
  make install

You need HIDAPI and USBRELAY:

git clone git://github.com/signal11/hidapi.git

Check out the readme, and install dependencies before installing.
then:

git clone https://github.com/darrylb123/usbrelay.git

Then, in usbrelay folder:

gcc -o usbrelay usbrelay.c -lhidapi-libusb

Then do:

ldconfig

Read more here:

• http://www.signal11.us/oss/hidapi/
• https://github.com/darrylb123/usbrelay

To get status:

./usbrelay 2>/dev/null

To get status in bash script:

$ eval $(sudo ./usbrelay 2>/dev/null)
$ echo $PSUIS_2

Turn on:

/usbrelay EO5ZA_1=1

Turn off:

/usbrelay EO5ZA_1=0