clang -O2 -Wall -Wextra -Werror=implicit-function-declaration devctl/posix_devctl.c -o devctl/posix_devctl -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lintl devctl/posix_devctl.c:4:10: fatal error: 'devctl.h' file not found #include ^ 1 error generated.