run - execute BASIC program
struct string *prog;
Run executes the file given by the string pointed to by prog.
First, as a precaution, this function uses access(2) to check that
prog refers to a file that is executable. Then all files are
flushed and closed. Finally, the new program is executed using exec(2).
This function implements a version of the RUN statement.
access(2), exec(2) in the UNIX Programmerís Manual
Error 51 (Internal error) is generated if exec fails.
The Basmark QuickBASIC Programmerís Manual