https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94931
--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> --- On Mon, May 04, 2020 at 08:23:17AM +0000, ryofurue at gmail dot com wrote: > > But, then the question is, why don't you need the -L option? as in > > gfortran -I/usr/include mysourcefile.f -L/usr/lib -lnetcdff -netcdf > > > Why is this asymmetry? It seems that there are "standard" places to place > libraries but not include files . . . I think you're seeing the effects of shared libraries. The loader has library information: % ldconfig -r | grep netcdf 453:-lnetcdf.15 => /usr/local/lib/libnetcdf.so.15 My advice is to always have the correct -L options.