unix (linux) has no such thing.....
there are some conventions, like .html, .c, .php, .conf, .pl
(which are NOT really executables, as such)..
Particularly when talking about executables, there is (are) no Extentions Required....
(and, you can have a Program name, like my.exe.program.which_is.executable.exe, if ya' want,
or just myp)
Hey, you Want exe.... Winders Maybe ?? ;-)