cc -O2 -pipe -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/S_ISUID.c -o fcntl/S_ISUID -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lstdthreads -lcrypt
fcntl/S_ISUID.c:3:2: error: "S_ISUID is not defined"
    3 | #error "S_ISUID is not defined"
      |  ^
1 error generated.