cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration sys_mman/msync.c -o sys_mman/msync -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
sys_mman/msync.c: In function ‘main’:
sys_mman/msync.c:46:14: error: implicit declaration of function ‘msync’; did you mean ‘fsync’? [-Wimplicit-function-declaration]
   46 |         if ( msync(ptr, pagesize, MS_SYNC) < 0 )
      |              ^~~~~
      |              fsync
sys_mman/msync.c:46:35: error: ‘MS_SYNC’ undeclared (first use in this function)
   46 |         if ( msync(ptr, pagesize, MS_SYNC) < 0 )
      |                                   ^~~~~~~
sys_mman/msync.c:46:35: note: each undeclared identifier is reported only once for each function it appears in