close

CLOSE(2)                   Linux Programmer's Manual                  CLOSE(2)



NAME
       close - close a file descriptor

SYNOPSIS
       #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 locks held on the file it was  associated  with,
       and  owned by the process, are removed (regardless of the file descrip-
       tor 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, or -1 if an error occurred.

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, SVID, POSIX, X/OPEN, BSD 4.3.  SVr4 documents an additional  ENO-
       LINK error condition.

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 disk quotas.

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



                                  2001-12-13                          CLOSE(2)