Re: getting streamDevice exception handler replyTimeout to write to a record [SEC=UNCLASSIFIED]

["Johnson, Andrew N. via Tech-talk" <tech-talk at aps.anl.gov>]

On Mar 31, 2020, at 10:39 PM, Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> wrote:

IMHO this is a cleaner solution that does not involving launching a separate process.

In the protocol file:

commsFail {

 #exec 'echo "comms fail on \$0"'; #Turn this off in production

 exec 'dbpf \$1:\$4 "Comms error"> /dev/null';  #/dev/null makes it silent

}

Strictly speaking an “exec” command in a StreamDevice protocol file isn't actually launching a separate process, it’s just running “dbpf” as an iocShell command, which I assume happens in the context of whatever thread is executing the protocol. You could run an external process if your exec string starts with the iocsh command “system” to launch it, but that isn’t what the above protocol snippet is doing.

</pedantic>

- Andrew

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Complexity comes for free, simplicity you have to work for.