The command$ variable function will take a string the is passed after the ebm macro and insert it into a macro.  This can be done via commandline or using a toolbar or quickpad button.

You can run a simple command line such as "ebrun.exe hello.ebm hello" to pass the string hello to the command$ function in a macro

See the community discussion for creating a button to pass a function to a macro:

https://community.rocketsoftware.com/discussion/pass-variable-to-macro-from-toolbar#bmaafa52c7-1ae1-427c-b69e-989c7b52603d