- launchd-dev - lists.macosforge.org

Adding KeepAlive in LauchDaemon plist
by Karthikeyan M 20 Sep '11

20 Sep '11

Hi, I am trying to create a Launch Daemon for EnCase binary file. I have to add KeepAlive to the Launch Daemon plist. The process should be alive even if it exists normally (with exit 0) or crashes with error. I tried adding <key>KeepAlive</key> in the Launch Daemon(below) created but this keeps on running the Program Arguments resulting in multiple process of the same binary. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>KeepAlive</key> <true/> <key>Label</key> <string>com.guidancesoftware.encase</string> <key>ProgramArguments</key> <array> <string>/usr/local/encase/Encase</string> <string>start</string> </array> <key>QueueDirectories</key> <array/> <key>RunAtLoad</key> <true/> <key>WatchPaths</key> <array/> </dict> </plist> Someone help me in changing the LauchDaemon plist so that the process kickstart if the Encase process exits? Thanks & Regards, Karthikeyan M

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Understanding sockpathmode
by Gian Luca Gaiba 31 Aug '11

31 Aug '11

Hi I'm a newby on launchd but I'm developing an app that needs deamons... I'm not posting a real coding question but only an "understanding" one what actually means sockpathmode in property list? what do this item means for launchd? i apologize for my english hope to be clear tnx Gian Luca

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Bug in Lion: WatchPath agents succeed, but respawned for a second launch
by Jerry Krinock 28 Jul '11

28 Jul '11

In Lion, launchd tasks with a WatchPath trigger are triggered as expected, but are then respawned to run after a second time after their ThrottleInterval. This does not happen in Snow Leopard. One would think that this bug might have something to do with document Auto Save if the WatchPath was opened in an app that had Auto Save enabled, but that is not necessary; as shown in the steps below, it occurs if I simply 'touch' the WatchPath. Same thing happens if I modify the WatchPath file in BBEdit 9.0, which does not have Auto Save enabled. Also, this bug does not require opening a text file; I discovered it by testing my app which launches a background tool which works for about 10 seconds and then quits. When running under OS X Lion, it always gets launched twice. Please look at my steps below and tell me if my expectations are incorrect. Does anyone think that this is not a serious bug in Lion? Thanks, Jerry Krinock STEPS TO REPRODUCE: 1. Create a target text file named "Junk.txt", with any text, in your Home folder. 2. Create a trigger text file named "TriggerFile.txt", with any text, on your Desktop. 3. Create a launch agent file named "jerry.launchd.test.plist" in ~/Library/LaunchAgents containing the following text: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>jerry.launchd.test</string> <key>ProgramArguments</key> <array> <string>/usr/bin/open</string> <string>/Users/jk/Junk.txt</string> </array> <key>ThrottleInterval</key> <integer>61</integer> <key>WatchPaths</key> <array> <string>/Users/jk/Desktop/TriggerFile.txt</string> </array> </dict> </plist> where, of course, you have replaced /jk/ with /yourShortName/. 4. Load the agent file by running this command launchctl load ~/Library/LaunchAgents/jerry.launchd.test.plist. 5. In Console.app, open a window to System Log Queries ▸ All Messages. 6. Trigger the agent by running this command: touch ~/Desktop/TriggerFile.txt Expected and Actual Result: The file Junk.txt opens in your text editor. Additional Unexpected Results: Message is logged into Console: com.apple.launchd.peruser.501: (jerry.launchd.test) Throttling respawn: Will start in 61 seconds Note that 61 seconds is the ThrottleInterval. 7. Close the window to Junk.txt which has opened. Additional Bad (but not unexpected) Result: The window to Junk.txt opens *again* 61 seconds after the first opening. Regression: Repeat the test in Snow Leopard; the target file is only opened once, as expected.

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Setting up an AF_UNIX based launchd server
by mailist＠ericgorr.net 25 Jul '11

25 Jul '11

I have been able to setup a AF_INET launchd based server, but, as I understand it, an AF_UNIX based server offers better performance and there is no need to even think about allowing anything outside of the local machine to access the server. I have made an attempt to get something working, but it is not working yet. I am sure there are several problems with the test code, which can be found at: http://ericgorr.net/pq/AF_UNIX.zip (Developed on Mac OS X 10.6.8 using Xcode 4) On the client side, I try to connect to the server with the following code: #define kServerSocketPath "/var/tmp/net.ericgorr.testserver/Socket" int client_connect( void ) { int socketFD = socket( AF_UNIX, SOCK_STREAM, 0 ); assert( socketFD != -1 ); struct sockaddr_un addr; addr.sun_len = sizeof( addr ); addr.sun_family = AF_UNIX; strcpy( addr.sun_path, kServerSocketPath ); int result; int err; result = connect( socketFD, (struct sockaddr *)&socketFD, sizeof( socketFD ) ); err = MoreUNIXErrno( result ); CFShow( CFStringCreateWithFormat( NULL, NULL, CFSTR( "client_connect: %d" ), err ) ); assert( err == 0 ); return socketFD; } However, the connect call sets errno to 2, which I believes means that it cannot find kServerSocketPath. On the server side, I have the following plist: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>EnableTransactions</key> <true/> <key>Label</key> <string>net.ericgorr.testserver</string> <key>Program</key> <string>/usr/local/libexec/testserver</string> <key>ProgramArguments</key> <array> <string>testserver</string> <string>launchd</string> </array> <key>Sockets</key> <dict> <key>net.ericgorr.testserver.sock</key> <dict> <key>SockFamily</key> <string>Unix</string> <key>SockPathName</key> <string>/var/tmp/net.ericgorr.testserver/Socket</string> <key>SockPathMode</key> <integer>438</integer> <key>SockType</key> <string>Stream</string> </dict> </dict> </dict> </plist> One question is how should /var/tmp/net.ericgorr.testserver/Socket be created? Another question is, after I can launch the server, the server will need to check in with launchd and I need to know what index should be passed to launch_data_array_get_index...? And, where is this documented? These questions seem like they should be straightforward... Thank you.

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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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Why no key to "Run once on restart"
by Jerry Krinock 24 May '11

24 May '11

It seems that a fairly popular trigger would be a job that runs once, when the computer is restarted or user logs in. But I don't see a key for this in launch.plist(5). To get that effect, I'm using the two keys StartOnMount + LaunchOnlyOnce. The former does the job because a filesystem must be mounted when a computer restarts, and the latter keeps it from starting multiple times in case another filesystem is mounted before it exits. This works, but is indirect and kludgey. Is there a better way to do this? The reason I want to do this is to restart a syncing task which may take a minute or so and thus could be interrupted by system shutdown. When my task begins, it loads this new "standby" StartOnMount+LaunchOnlyOnce agent to re-run the same task when the system starts up. But when my task ends normally, it unloads this agent. Therefore it only ever spawns if my task was interrupted. Thank you, Jerry Krinock

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Reading WatchPaths file into Virtual Memory attempts to spawn Program
by Jerry Krinock 08 May '11

08 May '11

I discovered behavior which causes *some* of the "sleepiness" I've reported in launchd WatchPaths. [1] Consider a launchd agent which has WatchPaths. If the program indicated by its ProgramArguments *reads* one of the watched files by invoking -[NSData dataWithContentsOfFile:options:error:] with options = NSMappedRead (aka NSDataReadingMapped), this file *reading* causes launchd to immediately try and re-launch the program. Since the program is already running (I guess), it logs one of these: com.apple.launchd.peruser.501 (MyJobLabel) Throttling respawn: Will start in <N> seconds where <N> is a random number between the job's (ThrottleInterval - 60) and ThrottleInterval. [2] I don't know why I was using NSMappedRead; it was some very old code. NSMappedRead is "A hint indicating the file should be mapped into virtual memory, if possible". When I changed that option to 0, the respawn no longer occurs. This is apparently one reason why launchd's WatchPaths sometimes goes to sleep on me after the job is run; it's been throttled. But I think I've also seen WatchPaths go to sleep indefinitely when my ThrottleInterval was only 5 minutes, so there's probably more to the story. The documentation for launchd's WatchPath states "This optional key causes the job to be started if any one of the listed paths are modified." I think that the word "modified" used in the context of a file is rather vague, since there are two data forks and different kinds of metadata. Does mapping a file into virtual memory constitute "modified"? Should I file a bug on either the documentation or this behavior? Thanks, Jerry Krinock [1] http://lists.macosforge.org/pipermail/launchd-dev/2011-May/000916.html [2] One would think that the random-ness might be related to the clock seconds when the read occurs, but it is not. The "Throttling respawn" message performs as stated; the program is indeed relaunched in <N> seconds. This message seems to be logged whenever one of the WatchPaths is touched while the ProgramArguments program is running. But it is not logged if one of the WatchPaths is touched multiple times before the program is launched. Rather strange.

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