Using variables in exec node commands

[Adam S]

I did a quick search and am surprised I didn't find anything relating to using variables in the commands executed by the exec node, unless I'm just missing something obvious?  I'm trying to pass the current date as a parameter in a command.  I guess I can always just create a bash script and do what I want there, but I thought this would be a feature of the exec node.

[Mark Setrem]

If I understand what you want to do I think you are missing something obvious.

If you double click on the exec node you should see that you can append the contents of the msg.payload to the exec command.

[Adam S]

That appears to work, but now I have an annoying warning that my command is blank.  The time needs to be inserted in the middle of the command so I can't just append it.  Something like the mustache template is what I'm looking for here.

[Dave C-J]

You can add extra parameters after as well - using the extra parameters box...

[Adam S]

That doesn't really help me unless you can explain how you're supposed to use it to insert the parameters in the middle of the command.

python3 /usr/local/bin/xlsx2csv '/home/pi/2-8-16 to 2-12-16 Schedule.xlsx' -n 'Sched 2-8' > csv2.csv && echo "$(tail -n +3 /home/pi/csv2.csv)" >/home/pi/csv2.csv

This is the command I am running.  Everything in bold needs to be dynamic.

[Mark Setrem]

So stick Python in the box and include the rest as the msg.payload

[Adam S]

That will work I guess.  Still would like to see something along the lines of mustache.  Is that something that can be added in a patch?

Example:
Inject node injecting date on 24 hour schedule > format node creating the date strings/fill an array > exec node with command "python3 /usr/local/bin/xlsx2csv '/home/pi/{{json.monday}} to {{json.friday}} Schedule.xlsx' -n 'Sched {{json.today}}' > csv2.csv && echo "$(tail -n +3 /home/pi/csv2.csv)" >/home/pi/csv2.csv"

[Dave C-J]

Or use the template node (which does do mustache) in front of the exec node.

[Julian Knight]

Nooooo! Not resorting to Python ;-)

As you suggest, add a template node upstream to format the payload as required for the parameter.

[Taha Zouhair]

Anyone knows if I can use a variable (i.e. msg.from) in the extra input parameters?

Thanks!

[Dave C-J]

Hi,

no.  but msg.payload can contain multiple space separated parameters.

[Waqas Aslam]

Hi Dave C-J

Is msg.payload always supposed to be appended at the end of command?

How can merge in between the command?

for example:

sha256sum filename.txt | awk '{print $1}'

here filename.txt is coming from msg.payload.

regards

[Mark Setrem]

why not append  "| awk '{print $1}'" to msg.payload before the exec node

i.e. msg.payload becomes  "filename.txt | awk '{print $1}'"

[Dave C-J]

or indeed use the extra line for parameters after msg.payload...

[Waqas Aslam]

the reason why I didn't want to append the later part (awk) with filename is because filenames are coming from Watch node.

[Waqas Aslam]

seems like that's the path I should follow :)

thanks