Re: Question on using launchd from a C program
Re: Question on using launchd from a C program
- Subject: Re: Question on using launchd from a C program
- From: Paul Nelson <email@hidden>
- Date: Fri, 09 Jun 2006 08:20:40 -0500
- Thread-topic: Question on using launchd from a C program
It's probably a real sin to suggest this, but since you are waiting for
lepoard anyway....
Add this, and the associated observeNotices to your background app:
[[NSDistributedNotificationCenter defaultCenter] addObserver:self
selector:@selector(observeNotices:)
name:nil object:nil
suspensionBehavior:NSNotificationSuspensionBehaviorDeliverImmediately ];
In observeNotices, print out the NSNotification name and object values.
You will get everything, since the above addObserver call didn't specify.
Look at what gets printed out. Here are some event names you might be
interested in:
com.apple.userWillLogOut - the object will be a string containing the
user id
com.apple.sessionDidMoveOffConsole - for fast user switching
com.apple.sessionDidMoveOnConsole - for fast user switching
Once you figure out what notifications you like, replace the addObserver
with specific calls to register for specific notifications.
I've used these calls from a "faceless background app". They work fine. If
you don't like objective C, then figure out how to make similar calls from
CoreFoundation.
Of course, these will just get you by until Apple fully documents how to do
this kind of thing in Leapord....
Paul Nelson
Thursby Software Systems, Inc.
> From: Mike Kobb <email@hidden>
> Date: Thu, 8 Jun 2006 19:09:38 -0700
> To: <email@hidden>
> Subject: Re: Question on using launchd from a C program
>
> Thanks for that! I did consider the login/logout hooks, and I think
> they could well work, but to install them you need administrator
> privileges, and ideally I would not like to have to have the user
> have to authenticate to set up the login behavior.
>
> I think what I'm going to do instead is write a very simple faceless
> app that will be set as a login item. It will launch my server when
> it launches at login (if the user chose login-time launch), and at
> logout it'll find the server and tell it to quit. Should be very
> straightforward, and has the advantage (compared to launchd) of
> working on older OSes as well.
>
> Appreciate the suggestion.
> --Mike
>
> On Jun 8, 2006, at 6:38 PM, Andre LaBranche wrote:
>
>>
>> On Jun 8, 2006, at 6:04 PM, Mike Kobb wrote:
>>
>>> Unfortunately, I need this to work, well, today if possible. ;-)
>>>
>>> I'm sorry if I mis-typed. It's login and logout that I care
>>> about. Not boot or shutdown (except insofar as shutdown implies
>>> logout). I want them to be able to choose to launch it at login,
>>> or do it manually. Then, if it's running when they log out
>>> (whichever of those two methods they chose), I want it to quit.
>>> ...
>>
>> Perhaps a loginhook / logouthook would work for the interim?
>>
>> http://developer.apple.com/documentation/MacOSX/Conceptual/
>> BPSystemStartup/Articles/CustomLogin.html
>>
>> Cheers,
>> -Andre
>>
>>>
>>> On Jun 8, 2006, at 4:37 PM, Dave Zarzycki wrote:
>>>
>>>> Will you be attending WWDC?
>>>>
>>>> Can you wait for Leopard?
>>>>
>>>> Why the asymmetric requirement of launching at boot, but exiting
>>>> at logout (as opposed to at boot/shutdown or login/logout)?
>>>>
>>>> davez
>>>>
>>>> On Jun 8, 2006, at 3:55 PM, Mike Kobb wrote:
>>>>
>>>>> Greetings,
>>>>>
>>>>> I'm working on a MacOS preference pane that is used to configure
>>>>> the options of a faceless background process (a music server).
>>>>>
>>>>> This process is a BSD process for historical reasons, but will
>>>>> run under the privileges of a particular user, and not as root.
>>>>>
>>>>> I want to have a pop-up in the prefs pane that allows the user
>>>>> to choose to manually launch the server (by clicking a "Start"
>>>>> button in the pane, or to have the server launch at startup.
>>>>> Either way, I want to be sure that the server quits when they
>>>>> log out.
>>>>>
>>>>> It seems like launchd is likely to be what I want, but there are
>>>>> a few things I could use some help with.
>>>>>
>>>>> I have figured out how to create the appropriate plist to make
>>>>> the server launch at login and quit at shutdown, and that seems
>>>>> to work fine.
>>>>>
>>>>> So, I have two questions:
>>>>>
>>>>> 1) Is it possible to set up launchd to not launch the process at
>>>>> login, but to shut it down at logout?
>>>>>
>>>>> 2) I want this all to be controlled by my preference pane.
>>>>> Obviously, it's no trouble to get it to write out the required
>>>>> plist file, but the part I'm not sure about is how to do the
>>>>> equivalent of a "launchctl load" or "launchctl unload"
>>>>> operation. I could exec this, I guess, but I prefer to use a
>>>>> proper C API rather than the exec mechanism whenever I can. I
>>>>> couldn't make heads or tails out of launch.h, I'm afraid.
>>>>>
>>>>> Thanks in advance,
>>>>> --Mike
>
>
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