NAME

       on_exit - register a function to be called at normal process termination

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <stdlib.h>

       int on_exit(void (*function)(int, void *), void *arg);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       on_exit():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           glibc 2.19 and earlier:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       The  on_exit()  function  registers  the  given  function  to  be called at normal process
       termination, whether via exit(3) or via return from the program's main().  The function is
       passed  the  status  argument  given to the last call to exit(3) and the arg argument from
       on_exit().

       The same  function  may  be  registered  multiple  times:  it  is  called  once  for  each
       registration.

       When  a  child  process  is  created  via  fork(2),  it  inherits  copies  of its parent's
       registrations.  Upon a successful call to one of the exec(3) functions, all  registrations
       are removed.

RETURN VALUE

       The  on_exit()  function returns the value 0 if successful; otherwise it returns a nonzero
       value.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                      │ Attribute     │ Value   │
       ├───────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │on_exit()                                                      │ Thread safety │ MT-Safe │
       └───────────────────────────────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       This function comes from SunOS 4, but is also present in glibc.  It no  longer  occurs  in
       Solaris  (SunOS 5).  Portable application should avoid this function, and use the standard
       atexit(3) instead.

NOTES

       By the time function is executed, stack (auto) variables may  already  have  gone  out  of
       scope.   Therefore,  arg  should not be a pointer to a stack variable; it may however be a
       pointer to a heap variable or a global variable.

SEE ALSO

       _exit(2), atexit(3), exit(3)