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 record locks (see
       fcntl(2)) 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 file descriptor referring to the underlying open file description (see open(2)), the resources associ-
       ated with the open file description 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; see signal(7).

       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 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 file system 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.)

       It  is  probably  unwise  to close file descriptors while they may be in use by system calls in other threads in the same
       process.  Since a file descriptor may be reused, there are some obscure race conditions that may  cause  unintended  side
       effects.

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

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2007-12-28                                                   CLOSE(2)