March 2010 - launchd-dev - lists.macosforge.org

WatchEvents and unlink
by Alfred Labrie 24 Mar '10

24 Mar '10

Hello It sounds like there is a new behavior with WatchEvents on Snow Leopard. Let's say, I watch for this file path: "/private/tmp/watch" - if I create the file, launch daemon is triggered - if I write + close the file, launch daemon is triggered - if I remove the file then I create a new file, launch daemon is no longer triggered On Leopard, remove then create the file would trigger the launch daemon. Typical watch.plist syntax would be: ... <dict> <key>KeepAlive</key> <false/> <key>Label</key> <string>inc.ninja.watch</string> <key>ProgramArguments</key> <array> <string>/path/to/execute</string> </array> <key>WatchPaths</key> <array> <string>/private/tmp/watch</string> </array> </dict> </plist> This is tested on Mac OS X 10.6.2 and above. Is it by design or is it a bug? Regards.

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Launchd and python
by Michael McCracken 15 Mar '10

15 Mar '10

Hi, I just spent some time figuring out how to get a launchd agent written in python (and using UNIX domain sockets) up and running. I think this was asked previously on the list, and since it wasn't straightforward to figure out how to make it work, I decided to write a post about it and put up some public example code. My post is here: http://michael-mccracken.net/2010/03/snakes-on-demand-how-to-write-a-python… The example code is on bitbucket here: http://bitbucket.org/mikemccracken/py-launchd/ I'd be interested to hear comments on how I've implemented it. In particular: - I use a socket in /private/tmp/ but saw some comments saying that that might not be good for long-lived agents (mine won't be, but for sample code it might be better to use something else?) - To avoid forcing a restart on first-run, I use system() to unload, then load the plist when my app starts up. This smells - what happens if I'm doing this while a second app is talking to a running instance of this agent? Is there a better way? Thanks for any comments - I'm interested in updating my public code with the *right way* once I figure it out :) Cheers, -mike

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Re: [launchd-dev] A question about launchd and cron
by wierzbowski 06 Mar '10

06 Mar '10

> Date: Fri, 5 Mar 2010 23:04:47 +0000 > From: Quinn <eskimo1(a)apple.com> > To: launchd-dev(a)lists.macosforge.org > Subject: Re: [launchd-dev] A question about launchd and cron > Message-ID: <p06240832c7b73e8627e1(a)[10.0.40.15]> > Content-Type: text/plain; charset="us-ascii" ; format="flowed" > > At 14:34 -0800 5/3/10, wierzbowski wrote: > >> Please let me know if this would be an appropriate subject for this list. > > Sure. Fire away! > > S+E For demonstration purposes I've set up a simple crontab and cronjob running as myself (i.e. non-root). Here is the crontab: SHELL="/bin/sh" PATH="/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin" HOME="/Users/wierzbowski" MAILTO="wierzbowski@somewhere" * * * * * /Users/wierzbowski/bin/helloworld Here is the content of /Users/wierzbowski/bin/helloworld: #!/bin/sh /bin/echo "hello world." exit 0 Here is the output when I run the script manually: hello world. Here is the output that is mailed to me when the script runs via cron: hello world. Here is the error recorded in the syslog: Mar 5 12:17:00 macbookpro com.apple.launchd[1] (0x10e4d0.cron[97753]): Could not setup Mach task special port 9: (os/kern) no access Basically, on all the systems I manage I get that "special port 9" error in the syslog every time cron executes a job. And it doesn't seem to matter if it's a root or non-root job, if I have the environment explicit defined or not, if the cronjob is a one-liner right in the crontab or if it calls another shell script, if the script generates output or not, if the script redirects any i/o or not, if the script writes any files or not, etc. I'm just trying to figure out if there's a fundamental flaw in my cron usage on OS X, or if I've hit a bug and I just have to accept a few thousand extra lines in the syslog every day. I also realize that cron has been deprecated in favor or straight up launchd, and I'll get around to converting one of these day I swear, but for the moment I don't have the luxury of bumping that project to the top of my stack. :) I did take a quick look at the launchd source code, and I see where the error message is coming from, but I'm definitely no programmerologist and I have no idea what triggers that particular bit of code. Thanks in advance for any insight. Wierzbowski

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A question about launchd and cron
by wierzbowski 05 Mar '10

05 Mar '10

Greetings! I'm a user, not a developer, and I'd like to ask a question about an error that launchd generates in the syslog when running cronjobs on 10.5.8. I've tried some general purpose Mac OS X forums but haven't found an answer. Please let me know if this would be an appropriate subject for this list. Thank you! Wierzbowski

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Re: [launchd-dev] Confused about sockets - please help!
by dreamcat four 03 Mar '10

03 Mar '10

Hi, Thanks for the clarification. Incidentally I found a nice pair of examples about it, to illustrate these different kinds of Sockets nesting: Example1: "/System/Library/LaunchDaemons/org.cups.cupsd.plist" Example2: "/System/Library/LaunchDaemons/org.cups.cups-lpd.plist" * 1 More Question - About "Listeners": <key>Sockets</key> <dict> <key>Listeners</key> <--- *** this *** Its used very commonly so im going to make it the "default". In the documentation it says that deamon developers should not be sensitive to this thing. *But* does launchd still let the deamon developer to see this key name in the returned results? In which case, (and maybe wrongly but nevertheless), they might end up writing some code that is sensitive to this key name? You know, to find their results from it and whatnot. Therefore: Is it better, worse, or no different to randomly generating the multiple key names as "Listeners314986", "Listeners349q323" etc. ? Heres how i must write my code otherwise, to decide whether or not to throw an error over this: # Method def sockets(keyname="Listeners", &block) # here we create the Sockets xml from whats in "&block" end # Usage # Create Plist scenario 1: sockets do sock_service_name "netbios-ssn" end # => Result: Ok. "Listeners" toplevel key is generated implicitly. # Create Plist scenario 2: sockets do sock_service_name "netbios-ssn" end sockets do sock_service_name "netbios" bonjour ['smb'] end # => Result: Exception error. because implicit "Listeners" key is declared twice. # Create Plist scenario 3: sockets "netbios-ssn" do sock_service_name "netbios-ssn" end sockets "netbios" do sock_service_name "netbios" bonjour ['smb'] end # => Result: Ok. Each Sockets entry has a unique key. # Create Plist scenario 4: sockets[0] do sock_service_name "netbios-ssn" end sockets[1] do sock_service_name "netbios" bonjour ['smb'] end # => Result: Ok. Each Sockets entry has a unique array index. The array of all sockets held within the "Listeners" toplevel key (implicit). # Create Plist scenario 5: sockets do sock_service_name "netbios-ssn" end sockets[0] do sock_service_name "netbios" bonjour ['smb'] end # => Result: Exception error. because implicit "Listeners" key is declared twice. :) dreamcat4 dreamcat4(a)gmail.com On Wed, Mar 3, 2010 at 11:45 AM, Quinn <eskimo1(a)apple.com> wrote: > At 20:19 +0000 2/3/10, dreamcat four wrote: >> >> Are all of these different possible structures interchangeable? > > It depends on your perspective. From the perspective of launchd, it doesn't > care which format you use. From the perspective of a launchd daemon > developer, each format offers unique advantages. > > o If the sockets perform distinct functions, the dictionary of dictionaries > approach lets the launchd daemon easily determine which socket is which. > > o If the sockets perform similar functions, Tthe dictionary of array of > dictionaries approach makes that obvious. > > If you're writing a tool to manipulate launchd plists, I'd recommend that > you work hard to preserve this distinction. A launchd daemon that expects > its checkin results to be in one one format is probably going to fail if > they are in the other. > > S+E > -- > Quinn "The Eskimo!" <http://www.apple.com/developer/> > Apple Developer Relations, Developer Technical Support, Core OS/Hardware > _______________________________________________ > launchd-dev mailing list > launchd-dev(a)lists.macosforge.org > http://lists.macosforge.org/mailman/listinfo.cgi/launchd-dev >

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Confused about sockets - please help!
by dreamcat four 03 Mar '10

03 Mar '10

Hi, I'm writing a library API to manipulate launchd plists (from Ruby). But after reading and re-reading the man page, still very uncertain whether theres any difference between: Sockets <dictionary of dictionaries... OR dictionary of array of dictionaries...> Are all of these different possible structures interchangeable? (ie meaning the same thing to launchd program?) For example: <key>Sockets</key> <dict> <key>Listeners</key> <array> <dict> <key>SockNodeName</key> <string>::1</string> <key>SockServiceName</key> <string>ipp</string> </dict> <dict> <key>SockNodeName</key> <string>127.0.0.1</string> <key>SockServiceName</key> <string>ipp</string> </dict> <dict> <key>SockPathMode</key> <integer>49663</integer> <key>SockPathName</key> <string>/private/var/run/cupsd</string> </dict> </array> </dict> or <key>Sockets</key> <dict> <key>listener1</key> <dict> <key>SockNodeName</key> <string>::1</string> <key>SockServiceName</key> <string>ipp</string> </dict> <key>listener2</key> <dict> <key>SockNodeName</key> <string>127.0.0.1</string> <key>SockServiceName</key> <string>ipp</string> </dict> <key>listener3</key> <dict> <key>SockPathMode</key> <integer>49663</integer> <key>SockPathName</key> <string>/private/var/run/cupsd</string> </dict> </dict> or <key>Sockets</key> <dict> <key>listener1</key> <array> <dict> <key>SockNodeName</key> <string>::1</string> <key>SockServiceName</key> <string>ipp</string> </dict> </array> <key>listener2</key> <array> <dict> <key>SockNodeName</key> <string>127.0.0.1</string> <key>SockServiceName</key> <string>ipp</string> </dict> </array> <key>listener3</key> <array> <dict> <key>SockPathMode</key> <integer>49663</integer> <key>SockPathName</key> <string>/private/var/run/cupsd</string> </dict> </array> </dict> I'd really love to get an answer here, as its the last thing needed to complete the API interface. Best regards dreamcat4 dreamcat4(a)gmail.com

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Launchd xml DTD?
by dreamcat four 01 Mar '10

01 Mar '10

Hi, Is there a DTD specifically for the launchd.plist format specification? The xml header shows: http://www.apple.com/DTDs/PropertyList-1.0.dtd Which definately *isnt* what im looking for. Tried parsing / grepping the manpage output but that was pretty much a waste of time. Best regards dreamcat4 dreamcat4(a)gmail.com

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