1.\" Copyright (c) 1980, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)close.2 8.2 (Berkeley) 4/19/94 33.\" $FreeBSD: src/lib/libc/sys/close.2,v 1.10.2.6 2001/12/14 18:34:00 ru Exp $ 34.\" $DragonFly: src/lib/libc/sys/close.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd April 19, 1994 37.Dt CLOSE 2 38.Os 39.Sh NAME 40.Nm close 41.Nd delete a descriptor 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In unistd.h 46.Ft int 47.Fn close "int d" 48.Sh DESCRIPTION 49The 50.Fn close 51call deletes a descriptor from the per-process object 52reference table. 53If this is the last reference to the underlying object, the 54object will be deactivated. 55For example, on the last close of a file 56the current 57.Em seek 58pointer associated with the file is lost; 59on the last close of a 60.Xr socket 2 61associated naming information and queued data are discarded; 62on the last close of a file holding an advisory lock 63the lock is released (see further 64.Xr flock 2 ) . 65However, the semantics of System V and 66.St -p1003.1-88 67dictate that all 68.Xr fcntl 2 69advisory record locks associated with a file for a given process 70are removed when 71.Em any 72file descriptor for that file is closed by that process. 73.Pp 74When a process exits, 75all associated file descriptors are freed, but since there is 76a limit on active descriptors per processes, the 77.Fn close 78function call 79is useful when a large quantity of file descriptors are being handled. 80.Pp 81When a process forks (see 82.Xr fork 2 ) , 83all descriptors for the new child process reference the same 84objects as they did in the parent before the fork. 85If a new process is then to be run using 86.Xr execve 2 , 87the process would normally inherit these descriptors. Most 88of the descriptors can be rearranged with 89.Xr dup2 2 90or deleted with 91.Fn close 92before the 93.Xr execve 2 94is attempted, but if some of these descriptors will still 95be needed if the execve fails, it is necessary to arrange for them 96to be closed if the execve succeeds. 97For this reason, the call 98.Dq Li fcntl(d, F_SETFD, 1) 99is provided, 100which arranges that a descriptor will be closed after a successful 101execve; the call 102.Dq Li fcntl(d, F_SETFD, 0) 103restores the default, 104which is to not close the descriptor. 105.Sh RETURN VALUES 106.Rv -std close 107.Sh ERRORS 108.Fn Close 109will fail if: 110.Bl -tag -width Er 111.It Bq Er EBADF 112.Fa D 113is not an active descriptor. 114.It Bq Er EINTR 115An interrupt was received. 116.El 117.Sh SEE ALSO 118.Xr accept 2 , 119.Xr execve 2 , 120.Xr fcntl 2 , 121.Xr flock 2 , 122.Xr open 2 , 123.Xr pipe 2 , 124.Xr socket 2 , 125.Xr socketpair 2 126.Sh STANDARDS 127The 128.Fn close 129function call is expected to conform to 130.St -p1003.1-90 . 131.Sh HISTORY 132A 133.Fn close 134function call appeared in 135.At v7 . 136