2004-11-03 13:51:07 +00:00
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.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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2007-04-12 22:42:49 +00:00
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.\"
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2004-11-03 13:51:07 +00:00
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified 1993-03-29, David Metcalfe
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.\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
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.\" Modified 2003-10-25, Walter Harms
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.\"
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2008-12-05 16:09:04 +00:00
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.TH ATEXIT 3 2008-12-05 "Linux" "Linux Programmer's Manual"
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2004-11-03 13:51:07 +00:00
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.SH NAME
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2005-06-14 11:22:06 +00:00
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atexit \- register a function to be called at normal process termination
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2004-11-03 13:51:07 +00:00
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "int atexit(void (*" function )(void));
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.fi
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.SH DESCRIPTION
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2007-05-12 09:06:04 +00:00
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The
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.BR atexit ()
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function registers the given \fIfunction\fP to be
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2005-06-14 11:22:06 +00:00
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called at normal process termination, either via
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2004-11-03 13:51:07 +00:00
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.BR exit (3)
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2005-06-23 10:01:26 +00:00
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or via return from the program's \fImain\fP().
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2004-11-03 13:51:07 +00:00
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Functions so registered are called in
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the reverse order of their registration; no arguments are passed.
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2008-12-05 16:08:38 +00:00
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The same function may be registered multiple times:
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it is called once for each registration.
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.LP
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2007-07-13 08:32:28 +00:00
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POSIX.1-2001 requires that an implementation allow at least
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.B ATEXIT_MAX
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(32) such functions to be registered.
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2005-06-14 11:22:06 +00:00
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The actual limit supported by an implementation can be obtained using
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2004-11-03 13:51:07 +00:00
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.BR sysconf (3).
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.LP
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2007-04-12 22:42:49 +00:00
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When a child process is created via
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2007-05-12 00:30:29 +00:00
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.BR fork (2),
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2007-05-30 15:34:47 +00:00
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it inherits copies of its parent's registrations.
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2007-04-12 22:42:49 +00:00
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Upon a successful call to one of the
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2007-05-21 21:23:17 +00:00
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.BR exec (3)
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2005-10-20 15:11:10 +00:00
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functions,
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2005-06-23 09:45:21 +00:00
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all registrations are removed.
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2004-11-03 13:51:07 +00:00
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.SH "RETURN VALUE"
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The
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.BR atexit ()
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function returns the value 0 if successful; otherwise
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intro.1, time.1, adjtimex.2, capget.2, eventfd.2, fcntl.2, getrlimit.2, getsockopt.2, gettimeofday.2, intro.2, ioctl_list.2, ioperm.2, mlock.2, pivot_root.2, poll.2, prctl.2, ptrace.2, sched_setscheduler.2, select_tut.2, semget.2, sigaltstack.2, signalfd.2, sysctl.2, timer_settime.2, timerfd_create.2, wait.2, CPU_SET.3, argz_add.3, assert_perror.3, atexit.3, backtrace.3, bcmp.3, clearenv.3, ctime.3, dl_iterate_phdr.3, dlopen.3, ecvt.3, errno.3, error.3, ether_aton.3, exit.3, fenv.3, ferror.3, finite.3, flockfile.3, fnmatch.3, fpathconf.3, fpclassify.3, ftime.3, ftok.3, ftw.3, fwide.3, getaddrinfo.3, gethostbyname.3, getlogin.3, getnameinfo.3, getnetent.3, getopt.3, getprotoent.3, getrpcent.3, getservent.3, glob.3, hsearch.3, inet.3, isalpha.3, iswalnum.3, iswalpha.3, iswblank.3, iswcntrl.3, iswctype.3, iswdigit.3, iswgraph.3, iswlower.3, iswprint.3, iswpunct.3, iswspace.3, iswupper.3, iswxdigit.3, longjmp.3, lsearch.3, malloc.3, matherr.3, mblen.3, mbsinit.3, mbtowc.3, on_exit.3, printf.3, pthread_attr_init.3, pthread_attr_setaffinity_np.3, pthread_attr_setdetachstate.3, pthread_attr_setguardsize.3, pthread_attr_setinheritsched.3, pthread_attr_setschedparam.3, pthread_attr_setschedpolicy.3, pthread_attr_setscope.3, pthread_attr_setstack.3, pthread_attr_setstackaddr.3, pthread_attr_setstacksize.3, pthread_cancel.3, pthread_cleanup_push.3, pthread_equal.3, pthread_getattr_np.3, pthread_getcpuclockid.3, pthread_setaffinity_np.3, pthread_setcancelstate.3, pthread_setconcurrency.3, pthread_setschedparam.3, pthread_setschedprio.3, ptsname.3, putenv.3, putgrent.3, raise.3, rcmd.3, regex.3, rexec.3, rpc.3, rpmatch.3, rtnetlink.3, scandir.3, sem_init.3, setaliasent.3, setbuf.3, setenv.3, setjmp.3, signbit.3, stdio_ext.3, strtod.3, strtol.3, strtoul.3, system.3, termios.3, timeradd.3, tzset.3, ualarm.3, wctomb.3, xdr.3, st.4, tty_ioctl.4, core.5, elf.5, proc.5, bootparam.7, capabilities.7, icmp.7, ip.7, ipv6.7, math_error.7, mdoc.samples.7, mq_overview.7, pthreads.7, raw.7, regex.7, socket.7, tcp.7, tzselect.8: Global fix: s/non-zero/nonzero/
The tendency in English, as prescribed in style guides like
Chicago MoS, is towards removing hyphens after prefixes
like "non-" etc.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2010-01-16 16:40:55 +00:00
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it returns a nonzero value.
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2007-05-19 04:30:20 +00:00
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, C89, C99, POSIX.1-2001.
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.SH NOTES
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Functions registered using
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.BR atexit ()
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(and
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.BR on_exit (3))
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are not called if a process terminates abnormally because
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of the delivery of a signal.
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2008-12-05 16:02:24 +00:00
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2008-12-05 16:07:09 +00:00
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If one of the functions registered functions calls
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.BR _exit (2),
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then any remaining functions are not invoked,
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and the other process termination steps performed by
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.BR exit (3)
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are not performed.
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2008-12-05 16:09:47 +00:00
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POSIX.1-2001 says that the result of calling
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.BR exit (3)
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more than once (i.e., calling
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.BR exit (3)
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within a function registered using
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.BR atexit (3))
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is undefined.
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On some systems (but not Linux), this can result in an infinite recursion;
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.\" This can happen on OpenBSD 4.2 for example, and is documented
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.\" as occurring on FreeBSD as well.
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.\" Glibc does "the Right Thing" -- invocation of the remaining
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.\" exit handlers carries on as normal.
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portable programs should not invoke
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.BR exit (3)
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inside a function registered using
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.BR atexit (3).
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2008-12-05 16:06:16 +00:00
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The
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.BR atexit ()
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and
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.BR on_exit (3)
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functions register functions on the same list:
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at normal process termination,
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the registered functions are invoked in reverse order
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of their registration by these two functions.
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2008-12-05 16:02:24 +00:00
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POSIX.1-2001 says that the result is undefined if
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.BR longjmp (3)
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is used to terminate execution of one of the functions registered
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.BR atexit ().
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2008-12-05 16:05:34 +00:00
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.\" In glibc, things seem to be handled okay
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2007-05-21 07:53:35 +00:00
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.SS "Linux Notes"
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Since glibc 2.2.3,
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.BR atexit ()
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(and
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.BR on_exit (3))
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can be used within a shared library to establish functions
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that are called when the shared library is unloaded.
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2004-11-03 13:51:07 +00:00
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.SH EXAMPLE
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.nf
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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2007-04-12 22:42:49 +00:00
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void
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bye(void)
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2007-04-05 12:36:57 +00:00
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{
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printf("That was all, folks\en");
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2004-11-03 13:51:07 +00:00
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}
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2007-04-12 22:42:49 +00:00
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int
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main(void)
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{
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long a;
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int i;
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2004-11-03 13:51:07 +00:00
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2007-04-05 12:36:57 +00:00
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a = sysconf(_SC_ATEXIT_MAX);
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printf("ATEXIT_MAX = %ld\en", a);
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2007-04-05 12:36:57 +00:00
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i = atexit(bye);
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if (i != 0) {
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2007-12-25 16:24:14 +00:00
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fprintf(stderr, "cannot set exit function\en");
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exit(EXIT_FAILURE);
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2007-04-05 12:36:57 +00:00
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}
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2007-12-25 16:24:14 +00:00
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exit(EXIT_SUCCESS);
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2004-11-03 13:51:07 +00:00
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}
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.fi
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.SH "SEE ALSO"
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2007-06-01 06:08:17 +00:00
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.BR _exit (2),
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.BR exit (3),
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.BR on_exit (3)
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