This is where you would enter any #! header that you want in the executable generated by the compiler. UNIX like operating systems such as Linux, FreeBSD, and Solaris will use the #! header to locate the interpreter. This allows you to run your executable without specifying the interpreter (a necessity for CGI applications). NOTE: You also need to set the executable permission bit of the executable for this to work. IMPORTANT: This header is ignored under non-UNIX like operating systems, so including this header does not prevent the executable from running under any supported operating system.
For example, if you plan to deploy your executable on Linux, and you know that the full pathname of the interpreter is /usr/local/bin/ivm, then you would just enter that pathname into this text box, and the compiler will generate the #! header for you.
NOTE: The command-line compiler can also generate #! headers (see the -h compiler option). If you wish to add, change, or delete the #! header of an existing executable then you can use the Irie Header Utility (see using the Irie Header Utility). Which can be useful if you can't, or don't want to recompile the program.