Virtual Sensors from bash-file

[Hathor27]

Hi there,

can anybody help me designing a more complex virtual sensor with a bash-file?
The fare-away goal should be to get a 3h-trend from a sensor like thb0 into thb9, from temperature, humidity and barometric pressure.

I tried the following to get a 3h-trend value (first just) from the barometric pressure:

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#! /bin/sh
#
# runs at /home/meteohub/vsensor_delta3h.sh
wget -q -O /dev/stdout "http://meteo.horn.dom/meteograph.cgi?text=all" | grep -E "actual_thb0_press_hpa|seqhour1_thb0_press_hpa" | gawk 'BEGIN {FS="_"} {print $4,$6}' | tr -s '\n' ' ' | gawk 'BEGIN {FS=" "} {printf "%.1f\n", lround ($2 - $5) }'
#

Then I set a new virtual sensor as:
NeueID Name Trigg Umrechnung
Data11 Trend thb0 /home/meteohub/vsensor_delta3h.sh

After saving this virtual sensor the data collecting process restarts. Then meteohub.log says:

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processing "/home/meteohub/vsensor_thb0_delta3h.sh" does not return a value string, reason is: 
error while doing write on socket 5558: Broken pipe

What do I have to change for it returns only the desired value?

Thx in advance

[Hathor27]

...is anybody out there beeing able to give me an advice?...

[wfpost]

Starting your command manually from the shell it stays empty, but works with my meteohub with my internal IP-adress and comes up with a valid value

Therefore >>
replace dnydns name with your internal IP

wget -q -O /dev/stdout "http://meteohub-IP/meteograph.cgi?text=all" | grep -E "actual_thb0_press_hpa|seqhour1_thb0_press_hpa" | gawk 'BEGIN {FS="_"} {print $4,$6}' | tr -s '\n' ' ' | gawk 'BEGIN {FS=" "} {printf "%.1f\n", lround ($2 - $5) }'

[Hathor27]

Therefore >>
replace dnydns name with your internal IP

Thanks for your intention, wfpost. I run my own name-server internally, and meteo is the name of meteohub in my horn.dom name-space.
If I type the wget-command manually at the console, it works fine with name as far as with ip: It returns a single value like 2.3
Even if I run the command within the bash file it works fine at command line.

Only If I setup the virtual-sensor within meteohub, it won't work - any idea what I'm doing wrong?...
I suppose there is something with the return value meteohub expects... what is the difference if meteohub runs a single command (like wget) or a bash file for a virtual sensor?

[skyewright]

If I type the wget-command manually at the console, it works fine with name as far as with ip: It returns a single value like 2.3
Even if I run the command within the bash file it works fine at command line.

I'm not up on bash or gawk.
What exactly is the sort of value that your bash file outputs to stdout?

I suppose there is something with the return value meteohub expects... what is the difference if meteohub runs a single command (like wget) or a bash file for a virtual sensor?

With a virtual sensor Meteohub is looking for output on stdout, and expects that output to be in the correct format for the relevant virtual sensor.

For example in perl, my output line for a DATA sensor might look like:

print "$virtualData\n";

Whatever is output, I'd not expect it to include a decimal point. The values are typically scaled up, e.g. a DATA value that is 1.25 would be presented as 100 times that, i.e. 125, and a T value that was 10.3°C would be presented as 10 times that, i.e. 103.

Does that help?

[Hathor27]

Thank you skyewright - you're absolutely right: It needs to be a numeric value without a decimal point.

But there is another thing: I defined a well working virtual sensor directly in the meteohub GUI as

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awk '{printf "%d %d %d %d %d %d %d %d", $3, $4, $5, $6, $7, $8 , $9, $10}'

That writes me the values of thb0 into thb2 (stupid!)

If I set up a bash file like

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#!/bin/sh
#
# runs as /home/meteohub/vsensor_thb2.sh
#
awk '{printf "%d %d %d %d %d %d %d %d", $3, $4, $5, $6, $7, $8 , $9, $10}'

and configure that within the meteohub GUI instead of the above, meteohub.log says:

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"/home/meteohub/vsensor_thb2.sh" does not return a value string, reason is: sh: /home/meteohub/vsensor_thb2.sh: /bin/sh^M: bad interpreter: No such file or directory

What am I doing wrong?! Why bad interpreter?

[Hathor27]

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/bin/sh^M: bad interpreter

OK - found

a DOS/Windows-Error: CRLF instead of LF

[Hathor27]

Now back to my previous issue: I want to build a more complex virtual sensor, calculating a 3h trend of thb0.

First I only want to set up the 3h trend of the barometric pressure (temperature and humidity follows later):

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#! /bin/sh
#
# runs as /home/meteohub/vsensor_thb0_delta3h.sh
#
wget -q -O /dev/stdout "http://meteohub-ip/meteograph.cgi?text=all" | grep -E "seqmin15_thb0_press_hpa" | gawk 'BEGIN {FS="_"} {print $4,$15}' | gawk 'BEGIN {FS=" "} {printf "0 0 0 %d 0 0\n", lround (($2 - $3) *100.0) }'

Running that script at the command line, it returns a proper string like

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0 0 0 -10 0 0

Setting up the same script as virtual sensor, meteohub.log says:

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logger (23.10.2011 21:30:18): processing "/home/meteohub/vsensor_thb0_delta3h.sh" does not return a value string, reason is: 
logger (23.10.2011 21:30:18): error while doing write on socket 5558: Broken pipe

Has anybody any idea on that?

May a barometric pressure value of thb be negative? Even if not, I did the same into data34 (with only one value), and the same message accours in meteohub.log - what does it mean and how can I get thru?

[Hathor27]

...not any crack willing to help?

I think there's something wrong handling the trigger value, but I'm to little into this mechanism - can anybody assist, please?

[admin]

try listening directly at port 5558 by "netcat localhost 5558" instead of the wget thing.

[Hathor27]

try listening directly at port 5558 by "netcat localhost 5558" instead of the wget thing.

Thank you so far. I tried it - it's much faster - but the error message is still the same...
...any more suggestions?

[admin]

it allows only one rquesting process at a time. When mutliple script invocations do read, it will fail.

[Hathor27]

it allows only one rquesting process at a time. When mutliple script invocations do read, it will fail.

How could I (would you) setup a virtual sensor with a script file then, please?
Is there another way to get this functionality?

[admin]

use two kinds of script. one that grabs data from the port and temporary saves this in a file, the other virtual sensor definitions use a variant that reads data from that file.

[Hathor27]

use two kinds of script. one that grabs data from the port and temporary saves this in a file, the other virtual sensor definitions use a variant that reads data from that file.

The second script I understand to start as virtual sensor - that's ok.
But where/how would you suggest to start the first script (comfortable way)?