June 2011 - launchd-dev - lists.macosforge.org

Install and load a launch daemon without a reboot
by Jeremy Reichman 20 Oct '11

20 Oct '11

What is considered the current best practice for installing and then running a launch daemon, while avoiding a reboot? I didn't see exactly what I was looking for in my list archive or found it in any documentation on installation packages. I have reviewed TN2083, specifically the "Starting a Daemon" section. That answers most of my question but it would be helpful to have confirmation. Besides the conditions listed in TN2083, I'd like my installer to behave well when installed to a disk other than the current startup volume. I need to target Mac OS X 10.5 and 10.6. It looks as if I'd need to test for the right conditions and then run launchctl to load the property list. Roughly -- not production code -- it looks like I'd need a postinstall and postupgrade script to do the following: # Test if the destination volume for the payload and the root volume path are the same if [ "$3" = "$4" ] ; then # Quick test to see if the script is run by root if [ `/usr/bin/whoami` = "root" ] ; then /bin/launchctl load "$3/Library/LaunchDaemons/com.vendor.launchdaemon.plist" fi fi exit 0 Is that the right approach? Thanks! -- Jeremy

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How to run a few instances of a daemon (agent)?
by Nick 12 Jul '11

12 Jul '11

Hello By default, launchd starts a daemon or an agent, by doing the following 1) either "launchctl load /path/to/daemon.plist" is executed, or the plist is loaded automatically when the system starts 2) "launchctl start" is executed (if <string>RunAnLoad</string> is set to <boolean>false</boolean> then, only one instance is being run. I am wondering, if I could run several instances of the same daemon or agent (using launchd). Would it be possible, or I need to daemonize the process by myself, using an old unix way? Thanks, Nick

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A process is started by root (daemon). Can it unload a background process, started by an ordinary user? (agent)
by Nick 13 Jun '11

13 Jun '11

Hello! I have a daemon, that is launched with root privileges and works with the network. And I would like this daemon to be able to unload an agent, that is started by a user. I have read about bootstrap namespaces, but I am not sure I have understood correctly what was meant. Can you please point me on how (if it is possible) to do this? I tried the following: first, i listed all the background apps that are loaded by launchd into the current user's bootstrap namespace $ launchctl list among other lines, i got the output: # com.eveningnick.myagent then i typed: $ sudo launchctl list and, as expected, I haven't got my "com.eveningnick.myagent" there, instead i have a daemon # com.eveningnick.mydaemon there is a command that allows to let an another command be executed "from a bootstrap namespace": (quote from "man launchctl"): bsexec PID command [args] This executes the given command in the same Mach bootstrap namespace hierachy as the given PID. i found that my agent has PID which equals to 4724 so, I have typed: $ sudo launchctl bsexec 4724 launchctl list I have noticed the daemon, but not an agent in the output. I tried the same with Finder's PID - and got the daemon again. Why does this happen? How should one use this bsexec option? Or a different approach should be used here? (I need a daemon to be able to enumerate all users bootstrap spaces and unload an agent from each of them, if it had been previously loaded) Thank you Nick

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An agent with Keep-Alive set to true (in this agent's plist)
by Nick 13 Jun '11

13 Jun '11

Hello! I would like to have my application launched all the time - even when user makes it quit, it relaunches itself (this is a kind of child protection system). OS X has exactly what i need - an agent, with Keep-Alive set to "true" in this agent's .plist file (i chose agent - because i need an interface for this application). The problem is when the system tries to quit (reboot/shut down), my agent "cancels the shut down" (it behaves exactly like i'd return "NO" in -applicationWillClose method of the Application delegate, except the fact that i am not returning anything there). I tried to set up "throttle respawn" time for the agent to 20 seconds in a plist file (it is not necessary for the agent to be restarted immediately after 1 second for me), but (as it seems) the "respawning" happen not necessarily in 20 seconds, but within 0-20 seconds interval. Which leads again to "the application MyAgent has cancelled the restart" when i want to shut down the machine. Is there any way to solve this issue? Thank you Nick

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WWDC sessions?
by Peter 03 Jun '11

03 Jun '11

Any launchd related event on this year's WWDC? Would be great to see some exciting enhancements with all the feature requests from the previous years.

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