fsync  -  synchronize a file's complete in-core state with
       that on disk

SYNOPSIS

       #include <unistd.h>

       int fsync(int fd);

DESCRIPTION

       fsync copies all in-core parts of a file to disk.

       In some applications, fdatasync is a more efficient alter­
       native to fsync.

RETURN VALUE

       On  success,  zero is returned.  On error, -1 is returned,
       and errno is set appropriately.

ERRORS

       EBADF  fd is not a valid file descriptor open for writing.

       EROFS, EINVAL
              fd  is  bound to a special file which does not sup­
              port synchronization.

       EIO    An error occurred during synchronization.

CONFORMING TO

       POSIX.1b (formerly POSIX.4)

SEE ALSO

       bdflush(2), fdatasync(2), sync(2), update(8), sync(8)