1.\" Copyright (c) 1980, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)close.2 8.2 (Berkeley) 04/19/94 7.\" 8.Dd 9.Dt CLOSE 2 10.Os BSD 4 11.Sh NAME 12.Nm close 13.Nd delete a descriptor 14.Sh SYNOPSIS 15.Fd #include <unistd.h> 16.Ft int 17.Fn close "int d" 18.Sh DESCRIPTION 19The 20.Fn close 21call deletes a descriptor from the per-process object 22reference table. 23If this is the last reference to the underlying object, the 24object will be deactivated. 25For example, on the last close of a file 26the current 27.Em seek 28pointer associated with the file is lost; 29on the last close of a 30.Xr socket 2 31associated naming information and queued data are discarded; 32on the last close of a file holding an advisory lock 33the lock is released (see further 34.Xr flock 2 ) . 35.Pp 36When a process exits, 37all associated file descriptors are freed, but since there is 38a limit on active descriptors per processes, the 39.Fn close 40function call 41is useful when a large quantity of file descriptors are being handled. 42.Pp 43When a process forks (see 44.Xr fork 2 ) , 45all descriptors for the new child process reference the same 46objects as they did in the parent before the fork. 47If a new process is then to be run using 48.Xr execve 2 , 49the process would normally inherit these descriptors. Most 50of the descriptors can be rearranged with 51.Xr dup2 2 52or deleted with 53.Fn close 54before the 55.Xr execve 56is attempted, but if some of these descriptors will still 57be needed if the execve fails, it is necessary to arrange for them 58to be closed if the execve succeeds. 59For this reason, the call 60.Dq Li fcntl(d, F_SETFD, 1) 61is provided, 62which arranges that a descriptor will be closed after a successful 63execve; the call 64.Dq Li fcntl(d, F_SETFD, 0) 65restores the default, 66which is to not close the descriptor. 67.Sh RETURN VALUES 68Upon successful completion, a value of 0 is returned. 69Otherwise, a value of -1 is returned and the global integer variable 70.Va errno 71is set to indicate the error. 72.Sh ERRORS 73.Fn Close 74will fail if: 75.Bl -tag -width Er 76.It Bq Er EBADF 77.Fa D 78is not an active descriptor. 79.It Bq Er EINTR 80An interrupt was received. 81.El 82.Sh SEE ALSO 83.Xr accept 2 , 84.Xr flock 2 , 85.Xr open 2 , 86.Xr pipe 2 , 87.Xr socket 2 , 88.Xr socketpair 2 , 89.Xr execve 2 , 90.Xr fcntl 2 91.Sh STANDARDS 92.Fn Close 93conforms to IEEE Std 1003.1-1988 94.Pq Dq Tn POSIX . 95