| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
CLOSE(2) Linux Programmer's Manual CLOSE(2)
close - close a file descriptor
#include <unistd.h>
int close(int fd);
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 file descriptor referring to the underlying open
file description (see open(2)), the resources associated 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.
close() returns zero on success. On error, -1 is returned, and errno
is set appropriately.
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.
SVr4, 4.3BSD, POSIX.1-2001.
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.
fcntl(2), fsync(2), open(2), shutdown(2), unlink(2), fclose(3)
This page is part of release 3.51 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)
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