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.\" manual page may be incorrect or out-of-date.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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2004-11-03 13:51:07 +00:00
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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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2007-05-12 09:06:04 +00:00
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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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2010-11-01 05:59:37 +00:00
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.BR atexit ())
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2008-12-05 16:09:47 +00:00
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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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2010-11-01 05:59:37 +00:00
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.BR atexit ().
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2008-12-05 16:09:47 +00:00
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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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intro.1, time.1, _syscall.2, accept.2, brk.2, capget.2, faccessat.2, futimesat.2, gethostname.2, intro.2, ioprio_set.2, kill.2, madvise.2, mlock.2, mount.2, msgget.2, perf_event_open.2, poll.2, readv.2, sched_rr_get_interval.2, sched_setscheduler.2, select.2, select_tut.2, shmget.2, stat.2, timer_create.2, ustat.2, vfork.2, wait.2, alloca.3, atexit.3, catopen.3, crypt.3, dbopen.3, fenv.3, fopen.3, getaddrinfo_a.3, gethostbyname.3, getutent.3, intro.3, login.3, mallopt.3, queue.3, regex.3, sigpause.3, sigsetops.3, stdio.3, strftime.3, strptime.3, sysconf.3, ttyslot.3, undocumented.3, cciss.4, console_codes.4, hpsa.4, initrd.4, intro.4, rtc.4, st.4, tty_ioctl.4, wavelan.4, acct.5, charmap.5, dir_colors.5, hosts.5, intro.5, termcap.5, utmp.5, intro.6, armscii-8.7, boot.7, bootparam.7, capabilities.7, cpuset.7, credentials.7, ddp.7, epoll.7, glob.7, intro.7, ip.7, ipv6.7, iso_8859-1.7, iso_8859-10.7, iso_8859-11.7, iso_8859-13.7, iso_8859-14.7, iso_8859-15.7, iso_8859-16.7, iso_8859-2.7, iso_8859-3.7, iso_8859-4.7, iso_8859-5.7, iso_8859-6.7, iso_8859-7.7, iso_8859-8.7, iso_8859-9.7, koi8-r.7, koi8-u.7, man-pages.7, man.7, math_error.7, netlink.7, numa.7, packet.7, path_resolution.7, pipe.7, pthreads.7, raw.7, rtnetlink.7, signal.7, socket.7, spufs.7, svipc.7, tcp.7, time.7, udp.7, udplite.7, unicode.7, unix.7, uri.7, utf-8.7, x25.7, intro.8: Global fix: use consistent capitalization in .SS headings
Capitalization in .SS sections across pages (and sometimes even
within a single page) is wildly inconsistent. Make it consistent.
Capitalize first word in heading, but otherwise use lower case,
except where English usage (e.g., proper nouns) or programming
language requirements (e.g., identifier names) dictate otherwise.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-02-24 14:08:38 +00:00
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.SS Linux notes
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2007-05-21 07:53:35 +00:00
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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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time.1, atexit.3, bsearch.3, dlopen.3, envz_add.3, errno.3, fmtmsg.3, getgrent_r.3, getline.3, getmntent.3, getnameinfo.3, getpass.3, getpwent_r.3, gets.3, isalpha.3, printf.3, puts.3, recno.3, scandir.3, stdarg.3, sysconf.3, termios.3, wordexp.3, null.4, core.5, dir_colors.5, issue.5, proc.5, termcap.5, utmp.5, ascii.7, cpuset.7, glob.7, man-pages.7, man.7, mdoc.7, mdoc.samples.7, regex.7: Revert 9f8e673e623d (whose global s%\\e%\\\\% caused problems)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-26 21:56:54 +00:00
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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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2007-04-05 12:36:57 +00:00
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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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time.1, atexit.3, bsearch.3, dlopen.3, envz_add.3, errno.3, fmtmsg.3, getgrent_r.3, getline.3, getmntent.3, getnameinfo.3, getpass.3, getpwent_r.3, gets.3, isalpha.3, printf.3, puts.3, recno.3, scandir.3, stdarg.3, sysconf.3, termios.3, wordexp.3, null.4, core.5, dir_colors.5, issue.5, proc.5, termcap.5, utmp.5, ascii.7, cpuset.7, glob.7, man-pages.7, man.7, mdoc.7, mdoc.samples.7, regex.7: Revert 9f8e673e623d (whose global s%\\e%\\\\% caused problems)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-26 21:56:54 +00:00
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printf("ATEXIT_MAX = %ld\en", a);
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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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i = atexit(bye);
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if (i != 0) {
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time.1, atexit.3, bsearch.3, dlopen.3, envz_add.3, errno.3, fmtmsg.3, getgrent_r.3, getline.3, getmntent.3, getnameinfo.3, getpass.3, getpwent_r.3, gets.3, isalpha.3, printf.3, puts.3, recno.3, scandir.3, stdarg.3, sysconf.3, termios.3, wordexp.3, null.4, core.5, dir_colors.5, issue.5, proc.5, termcap.5, utmp.5, ascii.7, cpuset.7, glob.7, man-pages.7, man.7, mdoc.7, mdoc.samples.7, regex.7: Revert 9f8e673e623d (whose global s%\\e%\\\\% caused problems)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2012-09-26 21:56:54 +00:00
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fprintf(stderr, "cannot set exit function\en");
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2007-12-25 16:24:14 +00:00
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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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2004-11-03 13:51:07 +00:00
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.BR exit (3),
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.BR on_exit (3)
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