I have been setting up Custom SSH Script/Sensors for our Linux boxes. The documentation and example are great, most scripts are running perfectly. I have run into an issue when trying to set the return value using a variable, for example:

This works fine from a script:
echo "0:50:Ok"

This always causes the value in the PRTG sensor to be 0 (like its a string):
COUNT=`expr 25 + 25`
echo "0:${COUNT}:Ok"

The output on the screen when manually running these is the same:
0:50:Ok
0:50:Ok

I've tried typeset -i, declare -i on the COUNT variable to be sure its an integer. I've tried changing around how the output is wrapped, and regardless of whether the script outputs 0:50:Ok, if the 50 came from a variable the sensor does not like it.

I'd love to be able to track the actual 'value' without building a crazy CASE statement to handle every possibility.

I've also tried setting the returncode as an variable, that seems to work just fine:
RETCODE="1"
echo "${RETCODE}:50:Warning"

Thanks for any direction on this.

Article Comments

Hi,

It is curious because the output looks similar but PRTG takes the result as a string and tries to parse the value between the colons and interpret it either as an integer or a float regarding the sensor-setting. Obviously the output is only similar on the first view. We are trying to fix this as soon as possible.

In the meantime please take COUNT=`expr 25 + 25` echo "0:$COUNT:Ok" instead of COUNT=`expr 25 + 25` echo "0:${COUNT}:Ok" to enforce encoding the output as a simple string.

Kind regards


Nov, 2012 - Permalink

Thank you. That did work against the simple `expr 25 + 25`, the sensor started showing 50.

I plugged in my original code. COUNT=`/usr/sbin/lsof -i @server.domain.org:1521 | wc -l` echo "0:$COUNT:Ok" It calculates the number of open connections between this server and our database. The output when run manually from the CLI looks as I would expect: 0:57:Ok (with the 57 fluctuating slightly for each run). Unfortunately the sensor in PRTG would still show 0.

I then tried to modify things a bit, just to see if the | wc -l was messing things up: COUNT=`cat /var/prtg/scripts/testing.sh | wc -l` echo "0:$COUNT:Ok"

I excpected the output to be 0:2:Ok, and it was. And the sensor showed the appropriate 2 for a value. So it looks like there's something about the lsof portion of the command messing things up. Outside the scopy of PRTG/Paessler, but I thought I'd post this in case anybody else runs into something similar.

I truly appreciate your help. If I find a cause/resolution I'll update this.

Jim


Nov, 2012 - Permalink

And now for the 'reply of shame'.

So from the CLI I would see the connection count I expected, great except I ran the script as root. I would then trigger the sensor and it said 0, because the prtg user I setup doesn't have permissions to see anything but its own processes when using lsof. Sigh. I've been doing this how long?

Thanks, Jim


Nov, 2012 - Permalink