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