cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration unistd/sync.c -o unistd/sync -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
unistd/sync.c: In function ‘main’:
unistd/sync.c:10:9: error: implicit declaration of function ‘sync’; did you mean ‘fsync’? [-Wimplicit-function-declaration]
   10 |         sync();
      |         ^~~~
      |         fsync