close
NAME
close - close a file descriptor
SYNOPSIS
#include <unistd.h> I int close(int fd );
DESCRIPTION
R 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
R 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
R 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
R 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
R 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.)
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