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atexit(3)                BSD Library Functions Manual                atexit(3)


NAME

     atexit -- register a function to be called on exit


SYNOPSIS

     #include <stdlib.h>

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

     int
     atexit_b(void (^block)(void));


DESCRIPTION

     The atexit() function registers the function func to be called at program
     exit, whether via exit(3) or via return from the program's main().  Func-
     tions so registered are called in reverse order; no arguments are passed.

     The atexit_b() function is like atexit() except the callback is a block
     pointer instead of a function pointer.

           Note: The Block_copy() function (defined in <Blocks.h>) is used by
           atexit_b() to make a copy of the block, especially for the case
           when a stack-based block might go out of scope when the subroutine
           returns.

     These callbacks must not call exit(); if it should be necessary to termi-
     nate the process while in such a function, the _exit(2) function should
     be used.  (Alternatively, the callbacks may cause abnormal process termi-
     nation, for example by calling abort(3).)

     At least 32 callbacks can always be registered; more are allowed as long
     as sufficient memory can be allocated.


RETURN VALUES

     The atexit() and atexit_b() functions return the value 0 if successful;
     otherwise the value -1 is returned and the global variable errno is set
     to indicate the error.


ERRORS

     [ENOMEM]           No memory was available to add the function to the
                        list.  The existing list of functions is unmodified.


SEE ALSO

     exit(3)


STANDARDS

     The atexit() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

BSD                              May 20, 2008                              BSD

Mac OS X 10.8 - Generated Sun Aug 26 12:25:03 CDT 2012
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