man-pages/man3/atexit.3

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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
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.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" References consulted:
.\" Linux libc source code
.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\" 386BSD man pages
.\" Modified 1993-03-29, David Metcalfe
.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
.\" Modified 2003-10-25, Walter Harms
.\"
.TH ATEXIT 3 2003-11-01 "" "Linux Programmer's Manual"
.SH NAME
atexit \- register a function to be called at normal program termination
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "int atexit(void (*" function )(void));
.fi
.SH DESCRIPTION
The \fBatexit()\fP function registers the given \fIfunction\fP to be
called at normal program termination, either via
.BR exit (3)
or via return from the program's \fBmain\fP().
Functions so registered are called in
the reverse order of their registration; no arguments are passed.
.LP
At least ATEXIT_MAX functions can be registered. This value
is at least 32. It can be obtained using
.BR sysconf (3).
.LP
By a successful call to one of the exec functions,
all registrations are undone.
.SH "RETURN VALUE"
The \fBatexit()\fP function returns the value 0 if successful; otherwise
it returns a nonzero value.
.SH EXAMPLE
.nf
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
void bye(void) {
printf("That was all, folks\en");
}
int main(){
long a;
int i;
a = sysconf(_SC_ATEXIT_MAX);
printf("ATEXIT_MAX = %ld\en", a);
i = atexit(bye);
if (i != 0) {
fprintf(stderr, "cannot set exit function\en");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
.fi
.SH "CONFORMING TO"
SVID 3, BSD 4.3, ISO 9899, POSIX 1003.1-2001
.SH "SEE ALSO"
.BR _exit (3),
.BR exit (3),
.BR on_exit (3)