1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" 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.\" from: @(#)close.2 6.4 (Berkeley) 3/10/91 33.\" $Id: close.2,v 1.4 1994/01/10 23:54:16 jtc Exp $ 34.\" 35.Dd March 10, 1991 36.Dt CLOSE 2 37.Os BSD 4 38.Sh NAME 39.Nm close 40.Nd delete a descriptor 41.Sh SYNOPSIS 42.Fd #include <unistd.h> 43.Ft int 44.Fn close "int d" 45.Sh DESCRIPTION 46The 47.Fn close 48call deletes a descriptor from the per-process object 49reference table. 50If this is the last reference to the underlying object, the 51object will be deactivated. 52For example, on the last close of a file 53the current 54.Em seek 55pointer associated with the file is lost; 56on the last close of a 57.Xr socket 2 58associated naming information and queued data are discarded; 59on the last close of a file holding an advisory lock 60the lock is released (see further 61.Xr flock 2 ) . 62.Pp 63When a process exits, 64all associated file descriptors are freed, but since there is 65a limit on active descriptors per processes, the 66.Fn close 67function call 68is useful when a large quantity of file descriptors are being handled. 69.Pp 70When a process forks (see 71.Xr fork 2 ) , 72all descriptors for the new child process reference the same 73objects as they did in the parent before the fork. 74If a new process is then to be run using 75.Xr execve 2 , 76the process would normally inherit these descriptors. Most 77of the descriptors can be rearranged with 78.Xr dup2 2 79or deleted with 80.Fn close 81before the 82.Xr execve 83is attempted, but if some of these descriptors will still 84be needed if the execve fails, it is necessary to arrange for them 85to be closed if the execve succeeds. 86For this reason, the call 87.Dq Li fcntl(d, F_SETFD, 1) 88is provided, 89which arranges that a descriptor will be closed after a successful 90execve; the call 91.Dq Li fcntl(d, F_SETFD, 0) 92restores the default, 93which is to not close the descriptor. 94.Sh RETURN VALUES 95Upon successful completion, a value of 0 is returned. 96Otherwise, a value of -1 is returned and the global integer variable 97.Va errno 98is set to indicate the error. 99.Sh ERRORS 100.Fn Close 101will fail if: 102.Bl -tag -width Er 103.It Bq Er EBADF 104.Fa D 105is not an active descriptor. 106.It Bq Er EINTR 107An interrupt was received. 108.El 109.Sh SEE ALSO 110.Xr accept 2 , 111.Xr flock 2 , 112.Xr open 2 , 113.Xr pipe 2 , 114.Xr socket 2 , 115.Xr socketpair 2 , 116.Xr execve 2 , 117.Xr fcntl 2 118.Sh STANDARDS 119.Fn Close 120conforms to 121.St -p1003.1-88 . 122