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CLOSE(2)		  FreeBSD System Calls Manual		      CLOSE(2)

NAME
     close -- delete a descriptor

SYNOPSIS
     #include <unistd.h>

     int
     close(int d);

DESCRIPTION
     The close() call deletes a	descriptor from	the per-process	object refer-
     ence 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 dis-
     carded; on	the last close of a file holding an advisory lock the lock is
     released (see further flock(2)).

     When a process exits, all associated file descriptors are freed, but
     since there is a limit on active descriptors per processes, 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 is	then to	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 if some of these descriptors will still be needed if the
     execve fails, it is necessary to arrange for them to be closed if the
     execve succeeds.  For this	reason,	the call ``fcntl(d, F_SETFD, 1)'' is
     provided, which arranges that a descriptor	will be	closed after a suc-
     cessful execve; the call ``fcntl(d, F_SETFD, 0)'' restores	the default,
     which is to not close the descriptor.

IMPLEMENTATION NOTES
     In	the non-threaded library close() is implemented	as the close syscall.

     In	the threaded library, the close	syscall	is assembled to
     _thread_sys_close() and close() is	implemented as a function which	locks
     d for read	and write, then	calls _thread_sys_close().  Before returning,
     close() unlocks d.

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 indi-
     cate the error.

ERRORS
     Close() will fail if:

     [EBADF]		D is not an active descriptor.

     [EINTR]		An interrupt was received.

SEE ALSO
     accept(2),	execve(2), fcntl(2), flock(2), open(2),	pipe(2), socket(2),
     socketpair(2)

STANDARDS
     The close() function call is expected to conform to ISO/IEC 9945-1:1990
     (``POSIX.1'').

HISTORY
     A close() function	call appeared in Version 7 AT&T	UNIX.

4th Berkeley Distribution	April 19, 1994	     4th Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY

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