close – close a file descriptor

USAGE
       #include <unistd.h>

       int close(int fd);

DESCRIPTION
       close()  closes  a  file descriptor, so that it no longer refers to any
       file and may be reused.  Any record locks (see fcntl(2))  held  on  the
       file  it  was  associated  with,  and owned by the process, are removed
       (regardless of the file descriptor that was used to obtain the lock).

       If fd is the last copy of a particular file  descriptor  the  resources
       associated  with it are freed; if the descriptor was the last reference
       to a file which has been removed using unlink(2) the file is deleted.

RETURN VALUE
       close() returns zero on success.  On error, -1 is returned,  and  errno
       is set appropriately.

ERRORS
       EBADF  fd isn’t a valid open file descriptor.

       EINTR  The close() call was interrupted by a signal.

       EIO    An I/O error occurred.

CONFORMING TO
       SVr4, 4.3BSD, POSIX.1-2001.

NOTES
       Not  checking  the return value of close() is a common but nevertheless
       serious programming error.  It is quite possible that errors on a  pre-
       vious  write(2) operation are first reported at the final close().  Not
       checking the return value when closing the file may lead to silent loss
       of data.  This can especially be observed with NFS and with disk quota.

       A successful close does not guarantee that the data has  been  success-
       fully  saved to disk, as the kernel defers writes. It is not common for
       a filesystem to flush the buffers when the stream  is  closed.  If  you
       need  to  be sure that the data is physically stored use fsync(2).  (It
       will depend on the disk hardware at this point.)

SEE ALSO
       fcntl(2), fsync(2), open(2), shutdown(2), unlink(2), fclose(3)