When trying to compile this little example… …I get a compiler error regarding the call to lseek(). The output is: For the record: I have also tried using both lseek(*foo, 5, SEEK_CUR); and lseek(&foo, 5, SEEK_CUR);, but that only makes things worse. (I really didn’t expect that to solve anything either.) Referring to the man-page for lseek(3): Synopsis off_t lseek(int