PROLOG¶

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.

NAME¶

atexit - register a function to run at process termination

SYNOPSIS¶

#include <stdlib.h>

int atexit(void (*func)(void));

DESCRIPTION¶

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.

RETURN VALUE¶

Upon successful completion, atexit() shall return 0; otherwise, it shall return a non-zero value.

ERRORS¶

No errors are defined.

The following sections are informative.

EXAMPLES¶

None.

APPLICATION USAGE¶

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().

RATIONALE¶

None.

FUTURE DIRECTIONS¶

None.

SEE ALSO¶

exit(), sysconf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT¶

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .