CLOSE(2) OpenBSD Programmer's Manual CLOSE(2)NAMEclose - delete a descriptor
SYNOPSIS
#include <unistd.h>
int
close(int d);
DESCRIPTION
The close() call deletes a descriptor from the per-process object
reference table. If this is the last reference to the underlying object,
the object will be deactivated. For example, on the last close of a
file, the current seek pointer associated with the file is lost; on the
last close of a socket(2), associated naming information and queued data
are discarded; and on the last close of a file holding an advisory lock,
the lock is released (see flock(2)). However, the semantics of System V
and IEEE Std 1003.1-1988 (``POSIX'') dictate that all fcntl(2) advisory
record locks associated with a file for a given process are removed when
any file descriptor for that file is closed by that process.
When a process exits, all associated file descriptors are freed, but
since there is a limit on active descriptors per process, the close()
function call is useful when a large quantity of file descriptors are
being handled.
When a process forks (see fork(2)), all descriptors for the new child
process reference the same objects as they did in the parent before the
fork. If a new process image is to then be run using execve(2), the
process would normally inherit these descriptors. Most of the
descriptors can be rearranged with dup2(2) or deleted with close() before
the execve(2) is attempted, but since some of these descriptors may still
be needed should the execve(2) fail, it is necessary to arrange for them
to be closed when the execve(2) succeeds. For this reason, the call
fcntl(d, F_SETFD, FD_CLOEXEC) is provided, which arranges that a
descriptor will be closed after a successful execve(2); the call fcntl(d,
F_SETFD, 0) restores the default, which is to not close the descriptor.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and the global integer variable errno is set to
indicate the error.
ERRORSclose() will fail if:
[EBADF] d is not an active descriptor.
[EINTR] An interrupt was received.
SEE ALSOaccept(2), closefrom(2), execve(2), fcntl(2), flock(2), open(2), pipe(2),
socket(2), socketpair(2)STANDARDSclose() conforms to IEEE Std 1003.1-1988 (``POSIX'').
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9