man3/exit.3

   1 .\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
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  23 .TH EXIT 3  2001-11-17 "" "Linux Programmer's Manual"
  24 .SH NAME
  25 exit \- cause normal process termination
  26 .SH SYNOPSIS
  27 .nf
  28 .B #include <stdlib.h>
  29 .sp
  30 .BI "void exit(int " status );
  31 .fi
  32 .SH DESCRIPTION
  33 The \fBexit()\fP function causes normal process termination and the
  34 the value of \fIstatus & 0377\fP is returned to the parent
  35 (see
  36 .BR wait (2)).
  37 All process termination functions registered with
  38 \fBatexit()\fP and \fBon_exit()\fP
  39 are called, in the reverse order of their registration,
  40 and all open streams are flushed and closed.
  41 Files created by \fItmpfile()\fP are removed.
  42 .LP
  43 The C standard specifies two constants
  44 \fIEXIT_SUCCESS\fP and \fIEXIT_FAILURE\fP
  45 that may be passed to \fBexit()\fP to indicate successful or unsuccessful
  46 termination, respectively.
  47 .SH "RETURN VALUE"
  48 The \fBexit()\fP function does not return.
  49 .SH "CONFORMING TO"
  50 SVID 3, POSIX, BSD 4.3, ISO 9899 (``ANSI C'')
  51 .SH NOTES
  52 During exit processing, a process termination function may
  53 register additional process termination
  54 functions with \fBatexit()\fP and \fBon_exit()\fP.
  55 These functions are added to the front of the list of
  56 process termination functions that remain to be called.
  57 .LP
  58 It is undefined what happens if one of the process termination
  59 functions calls either \fBexit()\fP or \fBlongjmp()\fP.
  60 .LP
  61 The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable
  62 (to non-Unix environments) than that of 0 and some nonzero value
  63 like 1 or \-1. In particular, VMS uses a different convention.
  64 .LP
  65 BSD has attempted to standardize exit codes - see the file
  66 .IR <sysexits.h> .
  67 .LP
  68 After \fBexit()\fP, the exit status must be transmitted to the
  69 parent process. There are three cases. If the parent has set
  70 SA_NOCLDWAIT, or has set the SIGCHLD handler to SIG_IGN, the
  71 status is discarded. If the parent was waiting on the child
  72 it is notified of the exit status. In both cases the exiting
  73 process dies immediately. If the parent has not indicated that
  74 it is not interested in the exit status, but is not waiting,
  75 the exiting process turns into a "zombie" process
  76 (which is nothing but a container for the single byte representing
  77 the exit status) so that the parent can learn the exit status when
  78 it later calls one of the \fIwait()\fP functions.
  79 .LP
  80 If the implementation supports the SIGCHLD signal, this signal
  81 is sent to the parent. If the parent has set SA_NOCLDWAIT,
  82 it is undefined whether a SIGCHLD signal is sent.
  83 .LP
  84 If the process is a session leader and its controlling terminal
  85 the controlling terminal of the session, then each process in
  86 the foreground process group of this controlling terminal
  87 is sent a SIGHUP signal, and the terminal is disassociated
  88 from this session, allowing it to be acquired by a new controlling
  89 process.
  90 .LP
  91 If the exit of the process causes a process group to become orphaned,
  92 and if any member of the newly orphaned process group is stopped,
  93 then a SIGHUP signal followed by a SIGCONT signal will be
  94 sent to each process in this process group.
  95 .SH "SEE ALSO"
  96 .BR _exit (2),
  97 .BR wait (2),
  98 .BR atexit (3),
  99 .BR on_exit (3),
 100 .BR tmpfile (3)