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ATEXIT(3P) POSIX Programmer's Manual ATEXIT(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
atexit — register a function to run at process termination
#include <stdlib.h>
int atexit(void (*func)(void));
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The atexit() function shall register the function pointed to by func,
to be called without arguments at normal program termination. At
normal program termination, all functions registered by the atexit()
function shall be called, in the reverse order of their registration,
except that a function is called after any previously registered
functions that had already been called at the time it was registered.
Normal termination occurs either by a call to exit() or a return from
main().
At least 32 functions can be registered with atexit().
After a successful call to any of the exec functions, any functions
previously registered by atexit() shall no longer be registered.
Upon successful completion, atexit() shall return 0; otherwise, it
shall return a non-zero value.
No errors are defined.
The following sections are informative.
None.
The functions registered by a call to atexit() must return to ensure
that all registered functions are called.
The application should call sysconf() to obtain the value of
{ATEXIT_MAX}, the number of functions that can be registered. There
is no way for an application to tell how many functions have already
been registered with atexit().
Since the behavior is undefined if the exit() function is called more
than once, portable applications calling atexit() must ensure that
the exit() function is not called at normal process termination when
all functions registered by the atexit() function are called.
All functions registered by the atexit() function are called at
normal process termination, which occurs by a call to the exit()
function or a return from main() or on the last thread termination,
when the behavior is as if the implementation called exit() with a
zero argument at thread termination time.
If, at normal process termination, a function registered by the
atexit() function is called and a portable application needs to stop
further exit() processing, it must call the _exit() function or the
_Exit() function or one of the functions which cause abnormal process
termination.
None.
None.
exec(1p), exit(3p), sysconf(3p)
The Base Definitions volume of POSIX.1‐2008, stdlib.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ATEXIT(3P)
Pages that refer to this page: stdlib.h(0p), exec(3p), exit(3p), _Exit(3p), pthread_atfork(3p)