If you compile without defining include “udf.h”, you will get an error message if variables are not defined, and cannot be compiled. DEFINE macro arguments must be defined in all on one line. If not, it will not compile and an error “Warning: no newline at end of file” will appear. Without compiling, it cannot be Loaded: Opening library “libudf” … Error: open_udf_library: No such file or directory When reading the case file, the error received when the UDF file cannot be found is: Library opening “libudf” … Error: Open_udf_library: couldn’t open library: libudf/ln86/2d/libudf.so