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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 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,  SVID,  POSIX,  X/OPEN,  4.3BSD.   SVr4  documents  an additional
       ENOLINK 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
       previous 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
       successfully 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)

                                  2001-12-13                          CLOSE(2)