HasMonitor.exe,  Version 1.00
Check the actual number of monitors connected at this very moment

Usage:   HasMonitor.exe  [ /A | /D[:number] ]  [ /Q ]

Where:   /A            list All monitors, including temporarily disconnected
                       ones (default: list only connected monitors)
         /D[:number]   include (number of) Default Monitor(s)
         /Q            Quiet mode (no screen output)

Notes:   Use this program's /A switch when run for the first time. If it
         reports one or more Default Monitors, check if these are real
         monitors, connected to the computer, or disconnected monitors.
         By default, this program treats Default Monitors as disconnected
         ones, but you can include a number of Default Monitors with the
         /D switch. Assuming 2 Default Monitors were reported, and 1 is a
         real monitor, use /D:1, if both are real use /D:2 or /D.
         The program's return code equals the number of monitors connected,
         or with /A switch the total number including disconnected ones,
         or -1 in case of (command line) errors.

Written by Rob van der Woude
https://www.robvanderwoude.com