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

NAME
     close -- delete a descriptor

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     close(int d);

DESCRIPTION
     The close() system	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;	on the last close of a file holding an advisory	lock the lock
     is	released (see further flock(2)).  However, the semantics of System V
     and IEEE Std 1003.1-1988 (``POSIX.1'') 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 processes, the close()
     system 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,
     FD_CLOEXEC)'' is provided,	which arranges that a descriptor will be
     closed after a successful execve; the call	``fcntl(d, F_SETFD, 0)''
     restores the default, which is to not close the descriptor.

RETURN VALUES
     The close() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     The close() system	call will fail if:

     [EBADF]		The d argument is not an active	descriptor.

     [EINTR]		An interrupt was received.

     [ENOSPC]		The underlying object did not fit, cached data was
			lost.

     [ECONNRESET]	The underlying object was a stream socket that was
			shut down by the peer before all pending data was
			delivered.

     In	case of	any error except EBADF,	the supplied file descriptor is	deal-
     located and therefore is no longer	valid.

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

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

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

FreeBSD	10.1		       January 22, 2012			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY

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