.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" 3. 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.
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.\"	$OpenBSD: atexit.3,v 1.5 2003/06/02 20:18:37 millert Exp $
.\"
.Dd June 29, 1991
.Dt ATEXIT 3
.Os
.Sh NAME
.Nm atexit
.Nd register a function to be called on exit
.Sh SYNOPSIS
.Fd #include <stdlib.h>
.Ft int
.Fn atexit "void (*function)(void)"
.Sh DESCRIPTION
The
.Fn atexit
function registers the given
.Fa function
to be called at program exit, whether via
.Xr exit 3
or via return from the program's
.Fn main .
Functions so registered are called in reverse order;
no arguments are passed.
At least 32 functions can always be registered,
and more are allowed as long as sufficient memory can be allocated.
.Sh RETURN VALUES
.Rv -std atexit
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ENOMEM
No memory was available to add the function to the list.
The existing list of functions is unmodified.
.El
.Sh SEE ALSO
.Xr exit 3
.Sh STANDARDS
The
.Fn atexit
function conforms to
.St -ansiC .