ATEXIT(3)              FreeBSD Library Functions Manual              ATEXIT(3)

NAME
     atexit - register a function to be called on exit

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     atexit(void (*function)(void));)(void));

     int
     atexit_b(void (^function)(void));)(void));

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

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

     At least 32 functions can always be registered, and more are allowed as
     long as sufficient memory can be allocated.

     The atexit_b() function behaves identically to atexit(), except that it
     takes a block, rather than a function pointer.

RETURN VALUES
     The atexit() function returns 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.

     [ENOSYS]           The atexit_b() function was called by a program that
                        did not supply a _Block_copy() implementation.

SEE ALSO
     at_quick_exit(3), exit(3)

STANDARDS
     The atexit() function conforms to ISO/IEC 9899:1990 ("ISO C90").

FreeBSD 13.1-RELEASE-p6        September 6, 2002       FreeBSD 13.1-RELEASE-p6