th-cmd

triggerhappy commander

th-cmd --socket socket [--passfd] [--tag foo] [--clear|--enable|--disable|--mode mode|--quit|--udev|--add devices...|--remove devices...]

Issues commands to a running triggerhappy daemon. It utilizes an unix domain socket bound by the daemon.

--socket socket socket file opened by the running triggerhappy daemon instance.
--add devices... Instruct the running daemon to open the input devices specified on the command line
--remove devices... Remove specified devices from the running daemon.
--clear Remove all devices from the running daemon.
--udev Deduce operation and device name from udev environment (for use in udev rules).
--disable Disable the execution of triggers.
--enable Re-enable the execution of triggers.
--mode newmode Change the mode of the triggerhappy daemon to newmode. If no new mode is specified, the daemon switches to default mode.
--passfd Instead of instructing the daemon to open the device, open the device and pass the file descriptor to the daemon. This allows the adding of new devices to a daemon having dropped its privileges, however the th-cmd process must have access to the device file.
--grab Grab the device; the triggerhappy daemon will try to get exclusive access to the device, other applications will not receive the events emitted by it.
--tag foo Label the added device with the tag foo; this can be used to limit the scope of event handlers to a subset of input devices.
--quit Terminate the triggerhappy daemon.

see

github.com/wertarbyte/triggerhappy WAS used by raspberry's raspi=config 
 log_daemon_msg "Checking if shift key is held down"
    if [ -x /usr/sbin/thd ] && timeout 1 thd --dump /dev/input/event* | grep -q "LEFTSHIFT\|RIGHTSHIFT"; then
      printf " Yes. Not enabling ondemand scaling governor"
      log_end_msg 0