clang -O2 -Wall -Wextra -Werror=implicit-function-declaration sys_mman/shm_unlink.c -o sys_mman/shm_unlink -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lintl ../out/minix/basic/sys_mman/shm_unlink.o: In function `main': sys_mman/shm_unlink.c:(.text+0x39f): undefined reference to `shm_open' sys_mman/shm_unlink.c:(.text+0x3c6): undefined reference to `shm_unlink' clang: error: linker command failed with exit code 1 (use -v to see invocation)