[launchd-dev] fork & exit in Shell Script (Revisited)

Charles Darwin DarwinsKernel at gmail.com
Mon Nov 10 10:13:11 PST 2008

On Nov 10, 2008, at 9:35 AM, Quinn wrote:

> At 13:56 -0500 5/11/08, Charles Darwin wrote:
>> What is the proper way of shutting down a daemon? Another daemon  
>> that runs a bit later?
> OK, I'm really confused )-:
> Let's start by agreeing on terminology.  I'm using the terms from  
> TN2083.  Please familiarise yourself with them (specifically  
> "daemon", "agent" and "background program").
> <http://developer.apple.com/technotes/tn2005/tn2083.html>
> If your background program is a "daemon" it is, by definition, not  
> running on behalf of a specific user.

Then I have got the definition wrong. Since my script doesn't have  
any GUI I thought it would be a daemon. But I'm getting the felling  
that that is not the right criteria.
Now lets call it and "agent", then according to what we have here:


I should be able to put the plist file into "personal LaunchAgents  
directories of specific users". I assume that would be ~/Library/ 
LaunchAgents (or at least that's what the man page for launchd reads):

> And thus it should not be affected by users logging in and out.

It is affected (taking it to be a daemon) and here is why. Here is  
the script:


if [ ! -d "/Volumes/tutorial" ] ; then
         /bin/mkdir -p /Volumes/tutorials && /sbin/mount_afp afp:// 
url/tutorials/ /Volumes/tutorials/

if [ ! -d "/Volumes/home" ] ; then
         /bin/mkdir -p /Volumes/homes && /sbin/mount_afp afp://url/ 
homes/ /Volumes/homes/

When user logs out OS X ejects the mounted afp volumes (tutorials &  
homes in the example above).

Now lets again call it an agent so I can use ~/Library/LaunchAgents  
(Per-user agents provided by the user) to launch my script whenever  
that particular user logs in. Well it just sits there and does  
nothing. The plist is loaded however:
$ launchctl list

Here is the plist by the way:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http:// 
<plist version="1.0">

> Furthermore, when you started talking about
>> /Users/user/Library/LaunchDaemons/<label>.plist
> I got even more confused because launchd doesn't load launchd  
> daemons from the user's home directory.

True. But as I asked before should it handle agents from ~/Library/ 

Thanks again for helping me with this Quinn.

> Can you give me a quick overview of the what you want your  
> background program to do?  I'm specifically interested in the  
> context in which the process should run and its expected lifecycle.
> S+E
> -- 
> Quinn "The Eskimo!"                    <http://www.apple.com/ 
> developer/>
> Apple Developer Relations, Developer Technical Support, Core OS/ 
> Hardware
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