I hope my message will get read soon and somebody will give me a solution. I use fortran to do simulation and gfortran is the compiler I use. Recently I migrated from Ubuntu 10.10 to 12.10. After installing gfortran then I tried to compile and run my fortran programs then the problem started. I successfully compiled the program but I am unable to execute it. (I work in a directory in shared partition, not in HOME directory). When I compiled the program and run it within HOME directory, everything worked fine. On my Ubuntu 10.10, I was able to compile and execute fortran program from everywhere not only within HOME directory. This is what I do for compiling and executing fortran program: gfortran hello.f90 -o hello # to compile it ./hello # to execute it I'm blind about PATH or anything like it (this has to do with it, I suspect) so please give me direction.