commandOutput

This small Skript script provides you with 2 functions, one executes a Minecraft command and returns its numeric output, the other a boolean value indicating whether or not the command got executed successfully.

This script should work on all versions >1.13, but I've only tested it on 1.15.2.
To use it you need the Skellett addon (& Skript).
The functions will only work if there's at least 1 player online.