Hi, I have a C project, star-charter, which is a straight clone from GitHub. >From my $Home in Ubuntu I have a folder, Cprojects, where I keep all my C/C++ projects, each in a separate sub-folder. My start-charter GitHub clone is in the star-charter subfolder The makefile is in the star-charter subfolder All of the source is in the src sub folder of star-charter Main.c is in the src sub-folder. Various libraries and headers are in sub-folders of src, for eample the gsl headers When I attempt to compile main.c which refere to the gsl headers in INCLUDE statements with the sub-folder gsl and header name , a file not found error is thrown. I have tried everything to correct this apparenty simple problem. Can you help Thanks G.McKay Sent from Mail for Windows 10