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exit(3)


NAME

   exit - cause normal process termination

SYNOPSIS

   #include <stdlib.h>

   void exit(int status);

DESCRIPTION

   The  exit() function causes normal process termination and the value of
   status & 0377 is returned to the parent (see wait(2)).

   All functions registered with atexit(3) and on_exit(3) are  called,  in
   the  reverse  order  of their registration.  (It is possible for one of
   these  functions  to  use  atexit(3)  or  on_exit(3)  to  register   an
   additional  function  to  be  executed  during exit processing; the new
   registration is added to the front of the list of functions that remain
   to  be  called.)   If  one of these functions does not return (e.g., it
   calls _exit(2), or kills itself  with  a  signal),  then  none  of  the
   remaining   functions  is  called,  and  further  exit  processing  (in
   particular, flushing of stdio(3) streams) is abandoned.  If a  function
   has  been registered multiple times using atexit(3) or on_exit(3), then
   it is called as many times as it was registered.

   All open stdio(3) streams are flushed and  closed.   Files  created  by
   tmpfile(3) are removed.

   The  C standard specifies two constants, EXIT_SUCCESS and EXIT_FAILURE,
   that may be passed to exit() to  indicate  successful  or  unsuccessful
   termination, respectively.

RETURN VALUE

   The exit() function does not return.

ATTRIBUTES

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

   
   Interface  Attribute      Value               
   
   exit()     Thread safety  MT-Unsafe race:exit 
   
   The exit() function uses a global variable that is not protected, so it
   is not thread-safe.

CONFORMING TO

   POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.

NOTES

   It  is  undefined what happens if one of the functions registered using
   atexit(3) and on_exit(3) calls either exit() or longjmp(3).  Note  that
   a  call  to execve(2) removes registrations created using atexit(3) and
   on_exit(3).

   The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable  (to
   non-UNIX  environments) than the use of 0 and some nonzero value like 1
   or -1.  In particular, VMS uses a different convention.

   BSD has attempted to standardize exit codes; see the file <sysexits.h>.

   After exit(), the  exit  status  must  be  transmitted  to  the  parent
   process.   There  are three cases.  If the parent has set SA_NOCLDWAIT,
   or has set the SIGCHLD handler to SIG_IGN, the status is discarded.  If
   the parent was waiting on the child, it is notified of the exit status.
   In both cases the exiting process dies immediately.  If the parent  has
   not  indicated that it is not interested in the exit status, but is not
   waiting, the exiting process turns into a "zombie"  process  (which  is
   nothing  but  a  container  for  the  single byte representing the exit
   status) so that the parent can learn the  exit  status  when  it  later
   calls one of the wait(2) functions.

   If  the implementation supports the SIGCHLD signal, this signal is sent
   to the parent.  If the parent has set  SA_NOCLDWAIT,  it  is  undefined
   whether a SIGCHLD signal is sent.

   If  the process is a session leader and its controlling terminal is the
   controlling  terminal  of  the  session,  then  each  process  in   the
   foreground  process group of this controlling terminal is sent a SIGHUP
   signal, and the terminal is disassociated from this  session,  allowing
   it to be acquired by a new controlling process.

   If  the  exit of the process causes a process group to become orphaned,
   and if any member of the newly orphaned process group is stopped,  then
   a  SIGHUP  signal  followed  by  a  SIGCONT signal will be sent to each
   process in this process group.  See setpgid(2) for  an  explanation  of
   orphaned process groups.

SEE ALSO

   _exit(2), setpgid(2), wait(2), atexit(3), on_exit(3), tmpfile(3)

COLOPHON

   This  page  is  part of release 4.09 of the Linux man-pages project.  A
   description of the project, information about reporting bugs,  and  the
   latest     version     of     this    page,    can    be    found    at
   https://www.kernel.org/doc/man-pages/.



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