1.\" $OpenBSD: close.2,v 1.9 2000/10/18 05:12:08 aaron Exp $ 2.\" $NetBSD: close.2,v 1.5 1995/02/27 12:32:14 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1991, 1993, 1994 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)close.2 8.2 (Berkeley) 4/19/94 36.\" 37.Dd April 19, 1994 38.Dt CLOSE 2 39.Os 40.Sh NAME 41.Nm close 42.Nd delete a descriptor 43.Sh SYNOPSIS 44.Fd #include <unistd.h> 45.Ft int 46.Fn close "int d" 47.Sh DESCRIPTION 48The 49.Fn close 50call deletes a descriptor from the per-process object 51reference table. 52If this is the last reference to the underlying object, the 53object will be deactivated. 54For example, on the last close of a file 55the current 56.Em seek 57pointer associated with the file is lost; 58on the last close of a 59.Xr socket 2 60associated naming information and queued data are discarded; 61on the last close of a file holding an advisory lock 62the lock is released. 63However, the semantics of System V and 64.St -p1003.1-88 65dictate that all 66.Xr fcntl 2 67advisory record locks associated with a file for a given process 68are removed when 69.Em any 70file descriptor for that file is closed by that process (see 71further 72.Xr flock 2 ) . 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. 88Most of 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 106Upon successful completion, a value of 0 is returned. 107Otherwise, a value of \-1 is returned and the global integer variable 108.Va errno 109is set to indicate the error. 110.Sh ERRORS 111.Fn close 112will fail if: 113.Bl -tag -width Er 114.It Bq Er EBADF 115.Fa D 116is not an active descriptor. 117.It Bq Er EINTR 118An interrupt was received. 119.El 120.Sh SEE ALSO 121.Xr accept 2 , 122.Xr execve 2 , 123.Xr fcntl 2 , 124.Xr flock 2 , 125.Xr open 2 , 126.Xr pipe 2 , 127.Xr socket 2 , 128.Xr socketpair 2 129.Sh STANDARDS 130.Fn close 131conforms to 132.St -p1003.1-88 . 133