After repeated trouble, I made the simplest possible test. This is my program file listing: Knoth.f95(~)-gedit program nothing end and this is my attempt to make an object file: ~$ gfortran -c Knoth.f95 ~$ gfortran -o Knoth.o gfortran: no input files; unwilling to write output files ~$ file Knoth.o Knoth.o : ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped What has gone wrong here?