Re: stupid question: how can I finish a program?

["Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca>]

Larry Kilgallen wrote:
> In article <3D6E507E.7010805@cogeco.ca>, "Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca> writes:
> 
> 
>>Even in "proper O/S" there are occaisions where cleanup is needed,
>>but not automatically done by the O/S. Here are 3 examples of
>>this, that can happen on [pick your] UNIX:
>>
>>   - Allocated _SHARED_ memory
>>   - Created message queues (IPC)
>>   - Create semaphores
>>
>>The reason these are not automatically cleaned up by the O/S is that
>>sometimes you want them to persist beyond the creating process'
>>lifetime (because they are shared by other processes).
> 
> VMS tends toward making those go away when the last accessing program
> exists.  At least for the first one there is an option to make it really
> permanent, but I don't think I have ever really wanted that.

UNIX does support the idea of a SEM_UNDO operation, where semaphores
are "undone" if the process is blown away. However, even that is
not necessarily the right thing to do (do you want to unlock a botched
shared memory region and hope for the best?)

>>This depends upon the application designer (not the O/S). The temp file
>>is indeed automatically cleaned up by the O/S if the application writer
>>uses the correct calls or does it correctly himself.
> 
> On top of all those other requirements, you want correct programming ?

Is there any other kind of Ada programmer? ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg