cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration fcntl/posix_fadvise.c -o fcntl/posix_fadvise -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
fcntl/posix_fadvise.c: In function ‘main’:
fcntl/posix_fadvise.c:14:23: error: implicit declaration of function ‘posix_fadvise’ [-Wimplicit-function-declaration]
   14 |         if ( (errno = posix_fadvise(fileno(fp), 0, 2, POSIX_FADV_SEQUENTIAL)) )
      |                       ^~~~~~~~~~~~~
fcntl/posix_fadvise.c:14:55: error: ‘POSIX_FADV_SEQUENTIAL’ undeclared (first use in this function)
   14 |         if ( (errno = posix_fadvise(fileno(fp), 0, 2, POSIX_FADV_SEQUENTIAL)) )
      |                                                       ^~~~~~~~~~~~~~~~~~~~~
fcntl/posix_fadvise.c:14:55: note: each undeclared identifier is reported only once for each function it appears in