This is a feature request for the Run Shell Script action settings pane to offer the option to possibly attempt to parse the command output, or minimally, remove training line ending characters from the output.
The Run Shell Script action is actually a bit misnamed. what it really does is spawn and run something from the command line. That could be a shell script, but it could also be a built-in unix command, and there are a LOT of useful commands there, or it could be some commercial program, something from github, etc., etc. In the case of things like relay boards, many sellers provide compiled code to read or write to their boards, and pretty much 100% of those will append a newline to their output. In other words, a non-technical user might use Run Shell Script to execute some arbitrary piece of compiled code which might return a boolean output. The way Run Shell Script runs today, it captures all standard output from the executed program, including the line ending characters (eg. newline). If the newline is included, Indigo will not properly parse the output as boolean.