The Windows command line uses start programname and start filename.ext to process the file as if the user had double-clicked it in the GUI shells we all know and love. MacOS's command line does the same with open. That is useful for those of us who don't know the exact program and location for opening unusual file types.
On Linux, ./filename.ext is to run scripts, and start filename.ext responds with an error because it's expecting a "job". So...
What is the standard CLI command to open a non-script file under whatever the registered type-handler under Linux? If it's not standard, what does Red Hat use?