Converting a (ddclient) startup command to launchdaemon plist

Question

Configuration: Mac Mini 10.9 with Server.app. My server has an internet connection with dynamic IP, and I am updating DDNS server with ddclient.Currently I have the following line appended to /etc/rc.common so it boots up and updates every 300 seconds. /usr/sbin/ddclient/ddclient -daemon&#x3D;300 -verbose -noquietThis command needs to run as root. I understand this is not the best practice but I have no idea how to convert this to a launchdaemon plist, can anyone shed some light on this for me? Thanks!

twtwtw · Answer

ddclient looks like it wants to be a continuously running daemon that handles its own periodic checks, so all you need launchd to do is launch it at startup and keep it running. So I think you want the following plist saved in /Library/LaunchDaemons/user.ddclient.updater.plist (the file name is a convention, not a necessity).&lt;?xml version&#x3D;"1.0" encoding&#x3D;"UTF-8"?&gt;&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;&lt;plist version&#x3D;"1.0"&gt;&lt;dict&gt;          &lt;key&gt;Label&lt;/key&gt;          &lt;string&gt;user.ddclient.updater&lt;/string&gt;          &lt;key&gt;ProgramArguments&lt;/key&gt;          &lt;array&gt;                    &lt;string&gt;/usr/sbin/ddclient/ddclient&lt;/string&gt;                    &lt;string&gt;-daemon&#x3D;300&lt;/string&gt;                    &lt;string&gt;-verbose&lt;/string&gt;                    &lt;string&gt;-noquiet&lt;/string&gt;          &lt;/array&gt;  &lt;key&gt;KeepAlive&lt;/key&gt;          &lt;dict&gt;                    &lt;key&gt;NetworkState&lt;/key&gt;                    &lt;true/&gt;          &lt;/dict&gt;&lt;/dict&gt;&lt;/plist&gt;when the plist is loaded into launchd it will keep ddclient running as long as the network is up.If I&#x27;ve misread the ddclient options and you need to get launchd to run ddclient periodically that&#x27;s easy enough; let me know.

burnduck · Answer

Thanks for the prompt reply, it worked beautifully but I have one quick follow up question.I tried putting the plist in /Library/LaunchDaemons, also chown&#x27;d it to root:wheel. When I restart the machine I can&#x27;t seem to find the process in (ps aux | grep "ddclient")? However launchctl says this plist is already loaded, mms:LaunchDaemons edmondsiu$ sudo launchctl load org.ddclient.cloudflare.updater.plist Password:user.ddclient.updater: Already loadedI can see it doing something in syslog, which is the only way for me to tell it&#x27;s loaded. I am just wondering if there&#x27;s a proper way to check whether it&#x27;s actually running? (Which also applied to other launchdaemons which might not syslog as frequently?)Thanks again! Message was edited by: burnduck

twtwtw · Answer

Well, I don&#x27;t normally use ps; if I want info on a process I use Activity Monitor.app. But I&#x27;ll point out that you seem to be using outdated syntax. See man ps, particularly the section at the bottom called Legacy Description.If you run sudo launchctl list | grep ddclient you should see output like xxxx x ddclient if the job is loaded properly. The first field is the pid of the running process, or a hyphen if the process is not running. The second field is the exit code of the process&#x27; last run.

burnduck · Answer

I have just noticed one thing regarding running ddclient this way, launchctl seem to be restarting the process as soon as it&#x27;s exited. Currently it&#x27;s being throttled to 10 seconds by the system, it doesn&#x27;t seem to obey the -daemon&#x3D;300 flag? I have had a look at KeepAlive and took out the NetworkState key but doesn&#x27;t seem to have made a difference. 😕Any tips on this?mms:LaunchDaemons edmondsiu$ sudo launchctl list | grep ddclient-          0          org.ddclient.cloudflare.updater

burnduck · Answer

I have made some changes to plist, as ddclient seem to try and act as daemon by itself which (i guess) might have clashed with launchd&#x27;s keepalive. (please correct me if i&#x27;m wrong). I am currently settling with the following plist, which I believe launchd will run every 5 minutes. Kind of a trial and error, please let me know if there&#x27;s anything I can do to further optimise it. 🙂&lt;?xml version&#x3D;"1.0" encoding&#x3D;"UTF-8"?&gt;&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;&lt;plist version&#x3D;"1.0"&gt;&lt;dict&gt;                              &lt;key&gt;Label&lt;/key&gt;                              &lt;string&gt;org.ddclient.cloudflare.updater&lt;/string&gt;                              &lt;key&gt;ProgramArguments&lt;/key&gt;                              &lt;array&gt;                                        &lt;string&gt;/usr/sbin/ddclient/ddclient&lt;/string&gt;                                        &lt;string&gt;-verbose&lt;/string&gt;                                        &lt;string&gt;-noquiet&lt;/string&gt;                              &lt;/array&gt;                              &lt;key&gt;StartInterval&lt;/key&gt;                              &lt;integer&gt;300&lt;/integer&gt;&lt;/dict&gt;&lt;/plist&gt;

twtwtw · Answer

that&#x27;s the way I would do it if I didn&#x27;t want it to run as daemon (allowing launchd to run it on a time schedule). If you do want to run it as a daemon you could try this (removes the KeepAlive key and adds a RunAtLoad key, on the theory that simpler is better):&lt;?xml version&#x3D;"1.0" encoding&#x3D;"UTF-8"?&gt;&lt;!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;&lt;plist version&#x3D;"1.0"&gt;&lt;dict&gt;          &lt;key&gt;Label&lt;/key&gt;          &lt;string&gt;user.ddclient.updater&lt;/string&gt;          &lt;key&gt;ProgramArguments&lt;/key&gt;          &lt;array&gt;                    &lt;string&gt;/usr/sbin/ddclient/ddclient&lt;/string&gt;                    &lt;string&gt;-daemon&#x3D;300&lt;/string&gt;                    &lt;string&gt;-verbose&lt;/string&gt;                    &lt;string&gt;-noquiet&lt;/string&gt;          &lt;/array&gt;          &lt;key&gt;RunAtLoad&lt;/key&gt;                &lt;true/&gt;&lt;/dict&gt;&lt;/plist&gt;If what you have works, though, then there&#x27;s no real need to mess with it.