This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the requirements described
here and the ISO C standard is unintentional. This volume of
POSIX.1‐2008 defers to the ISO C standard.
The value of status may be 0, EXIT_SUCCESS, EXIT_FAILURE, or any
other value, though only the least significant 8 bits (that is,
status & 0377) shall be available to a waiting parent process.
The exit() function shall first call all functions registered by
atexit(), in the reverse order of their registration, except that a
function is called after any previously registered functions that had
already been called at the time it was registered. Each function is
called as many times as it was registered. If, during the call to any
such function, a call to the longjmp() function is made that would
terminate the call to the registered function, the behavior is
If a function registered by a call to atexit() fails to return, the
remaining registered functions shall not be called and the rest of
the exit() processing shall not be completed. If exit() is called
more than once, the behavior is undefined.
The exit() function shall then flush all open streams with unwritten
buffered data and close all open streams. Finally, the process shall
be terminated with the same consequences as described in Consequencesof Process Termination.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
IEEE/The Open Group 2013 EXIT(3P)