.\" $NetBSD: close.2,v 1.5 1995/02/27 12:32:14 cgd Exp $ .\" .\" Copyright (c) 1980, 1991, 1993, 1994 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)close.2 8.2 (Berkeley) 4/19/94 .\" .Dd April 19, 1994 .Dt CLOSE 2 .Os BSD 4 .Sh NAME .Nm close .Nd delete a descriptor .Sh SYNOPSIS .Fd #include <unistd.h> .Ft int .Fo close .Fa "int fildes" .Fc .Sh DESCRIPTION The .Fn close 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 .Em seek pointer associated with the file is lost; on the last close of a .Xr 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 .Xr flock 2 ) . .Pp When a process exits, all associated file descriptors are freed, but since there is a limit on active descriptors per processes, the .Fn close function call is useful when a large quantity of file descriptors are being handled. .Pp When a process forks (see .Xr 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 .Xr execve 2 , the process would normally inherit these descriptors. Most of the descriptors can be rearranged with .Xr dup2 2 or deleted with .Fn close before the .Xr execve 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 .Dq Li fcntl(d, F_SETFD, 1) is provided, which arranges that a descriptor will be closed after a successful execve; the call .Dq Li fcntl(d, F_SETFD, 0) restores the default, which is to not close the descriptor. .Sh RETURN VALUES Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and the global integer variable .Va errno is set to indicate the error. .Sh ERRORS The .Fn close system call will fail if: .Bl -tag -width Er .\" ========== .It Bq Er EBADF .Fa fildes is not a valid, active file descriptor. .\" ========== .It Bq Er EINTR Its execution was interrupted by a signal. .\" ========== .It Bq Er EIO A previously-uncommitted .Xr write 2 encountered an input/output error. .El .Sh SEE ALSO .Xr accept 2 , .Xr execve 2 , .Xr fcntl 2 , .Xr flock 2 , .Xr open 2 , .Xr pipe 2 , .Xr socket 2 , .Xr socketpair 2 .Sh STANDARDS .Fn Close conforms to .St -p1003.1-88 .