evcap is a tool mainly for automating udev rules for input devices.

run evcap without parameters for the in-built help.

The normal use pattern is that you check in PROGRAM part of a udev rule
the event device capabilities with evcap, and if they matched (i.e.
RESULT=="true"), you can symlink that device as your
default "touchscreen", or "keyboard" or what ever you need.

Here is an example udev rule that checks for ABS_MT_POSITION_X,
ABS_MT_POSITION_Y, EV_SYN, and EV_ABS capabilities to find a touchscreen:

KERNEL=="event*", SUBSYSTEM=="input", ACTION=="add", PROGRAM="/usr/sbin/evcap /sys$devpath abs 60000000000000 ev 9", RESULT=="true", SYMLINK+="touchscreen"

When the right kind of device appears, it is symlinked as "/dev/touchscreen" for
standardized path in filesystem.