1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)atexit.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD$ 38.\" 39.Dd September 6, 2002 40.Dt ATEXIT 3 41.Os 42.Sh NAME 43.Nm atexit 44.Nd register a function to be called on exit 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In stdlib.h 49.Ft int 50.Fn atexit "void (*function)(void)" 51.Sh DESCRIPTION 52The 53.Fn atexit 54function 55registers the given 56.Fa function 57to be called at program exit, whether via 58.Xr exit 3 59or via return from the program's 60.Fn main . 61Functions so registered are called in reverse order; 62no arguments are passed. 63.Pp 64These functions must not call 65.Fn exit ; 66if it should be necessary to terminate the process while in such a 67function, the 68.Xr _exit 2 69function should be used. 70(Alternatively, the function may cause abnormal 71process termination, for example by calling 72.Xr abort 3 . ) 73.Pp 74At least 32 functions can always be registered, 75and more are allowed as long as sufficient memory can be allocated. 76.\" XXX {ATEXIT_MAX} is not implemented yet 77.Sh RETURN VALUES 78.Rv -std atexit 79.Sh ERRORS 80.Bl -tag -width Er 81.It Bq Er ENOMEM 82No memory was available to add the function to the list. 83The existing list of functions is unmodified. 84.El 85.Sh SEE ALSO 86.Xr exit 3 87.Sh STANDARDS 88The 89.Fn atexit 90function 91conforms to 92.St -isoC . 93