[launchd-dev] KeepAlive / NetworkState

[Nigel Kersten]

I've definitely used it before.  It doesn't always do exactly what I
want, but it's reliable enough.

$ head -n 13 /System/Library/LaunchDaemons/nmbd.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>Disabled</key>
	<true/>
	<key>KeepAlive</key>
	<dict>
		<key>NetworkState</key>
		<true/>
	</dict>
	<key>Label</key>
	<string>org.samba.nmbd</string>


So nmbd is using it under 10.5. You sure there's not an error in the
plist layout somewhere else?


On Sat, Mar 28, 2009 at 4:48 AM, Keith Mountin <mountin at mac.com> wrote:
> I am working on a launchd script to keep VNC alive.  We are having
> difficulty using the KeepAlive key with NetworkState.
>
> According to the man pages:
>
> KeepAlive <boolean or dictionary of stuff>
>
> This optional key is used to control whether your job is to be kept
> continuously running or to let demand and conditions
> control the invocation. The default is false and therefore only demand
> will start the job. The value may be set to true to
> unconditionally keep the job alive. Alternatively, a dictionary of
> conditions may be specified to selectively control
> whether launchd keeps a job alive or not. If multiple keys are provided,
> launchd ORs them, thus providing maximum flexibil-
> ity to the job to refine the logic and stall if necessary. If launchd
> finds no reason to restart the job, it falls back on
> demand based invocation. Jobs that exit quickly and frequently when
> configured to be kept alive will be throttled to con-
> verve system resources.
>
> SuccessfulExit <boolean>
>
> If true, the job will be restarted as long as the program exits and with
> an exit status of zero. If false, the job
> will be restarted in the inverse condition. This key implies that
> "RunAtLoad" is set to true, since the job needs to
> run at least once before we can get an exit status.
>
> NetworkState <boolean>
>
> If true, the job will be kept alive as long as the network is up, where
> up is defined as at least one non-loopback
> interface being up and having IPv4 or IPv6 addresses assigned to them.
> If false, the job will be kept alive in the
> inverse condition.
>
> But if I use
>
>        <key>KeepAlive</key>
>        <dict>
>                <key>NetworkState</key>
>                <true/>
>        </dict>
>
> I get
>
>  "Unknown key for boolean: NetworkState"
>
> Does launchd actually support
>
>        <key>KeepAlive</key>
>        <dict>
>                <key>NetworkState</key>
>                <true/>
>        </dict>
>
> Thank you,
>
> Keith
>
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