cc -pipe -O   -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations fcntl/O_DSYNC.c -o fcntl/O_DSYNC -D_POSIX_C_SOURCE=202405L  -lm -lpthread -lrt  -lrt -lcrypt
fcntl/O_DSYNC.c:4:2: error: #error "O_DSYNC is not defined"
 #error "O_DSYNC is not defined"
  ^~~~~