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CLOSE(2)		  FreeBSD System Calls Manual		      CLOSE(2)

NAME
     close -- delete a descriptor

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <unistd.h>

     int
     close(int d);

DESCRIPTION
     The close() system	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 seek pointer associated with the file is lost;	on the last
     close of a	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 flock(2)).

     When a process exits, all associated descriptors are freed, but since
     there is a	limit on active	descriptors per	processes, the close() system
     call is useful when a large quantity of file descriptors are being	han-
     dled.

     When a process calls 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 execve(2), the process would
     normally inherit these descriptors.  Most of the descriptors can be re-
     arranged with dup2(2) or deleted with close() before the execve() is at-
     tempted, but if some of these descriptors will still be needed if the
     execve() fails, it	is necessary to	arrange	for them to be closed only if
     the execve() succeeds.  For this reason, the system call

	   fcntl(d, F_SETFD, 1);

     is	provided, which	arranges that a	descriptor "d" will be closed after a
     successful	execve(); the system call

	   fcntl(d, F_SETFD, 0);

     restores the default, which is to not close descriptor "d".

RETURN VALUES
     Upon successful completion, a value of 0 is returned.  Otherwise, a value
     of	-1 is returned and errno is set	to indicate the	error.

ERRORS
     close() will fail if:

     [EBADF]		d is not an active descriptor.

     [EINTR]		An interrupt was received.

SEE ALSO
     accept(2),	execve(2), fcntl(2), flock(2), open(2),	pipe(2), socket(2),
     socketpair(2)

STANDARDS
     The close() function conforms to ISO/IEC 9945-1:1990 ("POSIX.1").

HISTORY
     The close() function appeared in Version 1	AT&T UNIX.

FreeBSD	13.0		       September 1, 2019		  FreeBSD 13.0

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY

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