cc -pthread   -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/O_SYNC.c -o fcntl/O_SYNC -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt  -lintl -liconv
fcntl/O_SYNC.c:3:2: error: #error "O_SYNC is not defined"
    3 | #error "O_SYNC is not defined"
      |  ^~~~~