man3/on_exit.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  25 .\" References consulted:
  26 .\"     Linux libc source code
  27 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  28 .\"     386BSD man pages
  29 .\" Modified 1993-04-02, David Metcalfe
  30 .\" Modified 1993-07-25, Rik Faith (faith@cs.unc.edu)
  31 .TH ON_EXIT 3  2017-09-15 "GNU" "Linux Programmer's Manual"
  32 .SH NAME
  33 on_exit \- register a function to be called at normal process termination
  34 .SH SYNOPSIS
  35 .nf
  36 .B #include <stdlib.h>
  37 .PP
  38 .BI "int on_exit(void (*" function ")(int , void *), void *" arg );
  39 .fi
  40 .PP
  41 .in -4n
  42 Feature Test Macro Requirements for glibc (see
  43 .BR feature_test_macros (7)):
  44 .in
  45 .PP
  46 .BR on_exit ():
  47     Since glibc 2.19:
  48         _DEFAULT_SOURCE
  49     Glibc 2.19 and earlier:
  50         _BSD_SOURCE || _SVID_SOURCE
  51 .SH DESCRIPTION
  52 The
  53 .BR on_exit ()
  54 function registers the given
  55 .I function
  56 to be
  57 called at normal process termination, whether via
  58 .BR exit (3)
  59 or via return from the program's
  60 .IR main ().
  61 The
  62 .I function
  63 is passed the status argument given to the last call to
  64 .BR exit (3)
  65 and the
  66 .I arg
  67 argument from
  68 .BR on_exit ().
  69 .PP
  70 The same function may be registered multiple times:
  71 it is called once for each registration.
  72 .PP
  73 When a child process is created via
  74 .BR fork (2),
  75 it inherits copies of its parent's registrations.
  76 Upon a successful call to one of the
  77 .BR exec (3)
  78 functions, all registrations are removed.
  79 .SH RETURN VALUE
  80 The
  81 .BR on_exit ()
  82 function returns the value 0 if successful; otherwise
  83 it returns a nonzero value.
  84 .SH ATTRIBUTES
  85 For an explanation of the terms used in this section, see
  86 .BR attributes (7).
  87 .TS
  88 allbox;
  89 lb lb lb
  90 l l l.
  91 Interface       Attribute       Value
  92 T{
  93 .BR on_exit ()
  94 T}      Thread safety   MT-Safe
  95 .TE
  96 .sp 1
  97 .SH CONFORMING TO
  98 This function comes from SunOS 4, but is also present in glibc.
  99 It no longer occurs in Solaris (SunOS 5).
 100 Portable application should avoid this function, and use the standard
 101 .BR atexit (3)
 102 instead.
 103 .SH NOTES
 104 By the time
 105 .I function
 106 is executed, stack
 107 .RI ( auto )
 108 variables may already have gone out of scope.
 109 Therefore,
 110 .I arg
 111 should not be a pointer to a stack variable;
 112 it may however be a pointer to a heap variable or a global variable.
 113 .SH SEE ALSO
 114 .BR _exit (2),
 115 .BR atexit (3),
 116 .BR exit (3)