exit(3)

NAME

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 exit - 정상적으로 프로세스를 종료한다.

SYNOPSIS 

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#include <stdlib.h>  void exit(int status);

DESCRIPTION 

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exit()함수는 프로세스를 정상종료 시키며, 이때 종료 값으로 status & 0377 로넘겨준다.
부모 프로세스는 wait(2)를 이용해서 자식 프로세스의 종료값을 읽어 올수 있다.

exit()가 호출되면 atexit(3)와 on_exit(3)에 의해서 등록된 함수들이 먼저 실행된다.
그 후 모든 열린 스트림을 비우고(flush)닫는다. tmpfile(3)에 의해서 생성된 임시파일도 이때 삭제된다.

표준 C에서는 exit()의 종료값을 위해서 EXIT_SUCCESS 와 EXIT_FAILURE를 준비해두고 있다.

RETURN VALUE

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 exit() 함수는 아무것도 리턴하지 않는다.

CONFORMING TO

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

NOTES

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       It  is  undefined what happens if one of the functions registered using
       atexit(3) and on_exit(3) calls either exit() or longjmp(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 pro-
       cess.  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  sta-
       tus)  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 fore-
       ground process group of this controlling terminal is sent a SIGHUP sig-
       nal,  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  pro-
       cess in this process group.

SEE ALSO

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