Usage: marktext [commands] [path]
Available commands:
--debug Enable debug mode
--safe Disable plugins and other user configuration
--dump-keyboard-layout Dump keyboard information
--version Print version information
--help Print this help message
marktext should point to your installation of Mark Text. The exact location will vary from platform to platform. Since I'm on macOS, I created convenient alias for the version of Mark Text that I have installed.
alias marktext="/Applications/Mark\ Text.app/Contents/MacOS/Mark\ Text"