The exit and _Exit functions terminate a process.
Before termination, exit performs the following functions in the order listed:
- Call the functions registered with the atexit(3) function, in the reverse order of their registration.
- Flush all open output streams.
- Close all open streams.
- Unlink all files created with the tmpfile(3) function.
The _Exit function terminates without calling the functions registered with the atexit(3) function, and may or may not perform the other actions listed. Both functions make the low-order eight bits of the status argument available to a parent process which has called a wait 2 -family function.
The C Standard (-isoC-99) defines the values 0, EXIT_SUCCESS, and EXIT_FAILURE as possible values of status. Cooperating processes may use other values; in a program which might be called by a mail transfer agent, the values described in sysexits(3) may be used to provide more information to the parent process.
Note that exit does nothing to prevent bottomless recursion should a function registered using atexit(3) itself call exit. Such functions must call _Exit instead (although this has other effects as well which may not be desired).
The exit and _Exit functions never return.
_exit(2), wait(2), atexit(3), intro(3), sysexits(3), tmpfile(3)