Scripting systemcommand argument passed badly

[iamchrislaurie]

The following command works from the command line (using Linux):

audtool set-volume $(('audtool get-volume' - 5))

I cannot get that to script. I have tried many variants of the following

systemcommand:audtool arg1:"set-volume" arg2:"$(('audtool get-volume' - 5))"

Is there some syntax trick to getting the exact line passed to the OS?

[janosvitok]

Maybe you need to call bash to do the parameter expansion.

systemcommand:bash arg1: "audtool" arg2:"set-volume" arg3:"$(('audtool get-volume' - 5))"

[iamchrislaurie]

Thank you for the response Jano!

Unfortunately that did not work.

[sbenejam]

This is a command that calls a python test script that I use: systemcommand:python-script.py arg:dspdfviewer arg:P
Maybe it could help.

[plugz]

Try this one:

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systemcommand:bash arg1:"-c" arg2:"audtool set-volume $(($(audtool get-volume) - 5))"

[mcallegari]

I have written an example in the documentation, so where did you guys read arg1, arg2, etc ?

http://www.qlcplus.org/docs/scripteditor.html

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systemcommand:/usr/bin/vlc arg:-f arg:/home/user/video.mp4 // plays my video with VLC in fullscreen

most likely this is what you want

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systemcommand:audtool arg:set-volume arg:"$(('audtool get-volume' - 5))"

By the way, this looks more like a usage question rather than a issue report...

[plugz]

I have written an example in the documentation, so where did you guys read arg1, arg2, etc ?

You're right, arg1 arg2 etc is useless.

But it works. You can also replace "arg" with "hi" or "hello", it will work too. Should a github issue be opened for this ?

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systemcommand:audtool arg:set-volume arg:"$(('audtool get-volume' - 5))"

This does not work, because

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$((`audtool get-volume`))

is something that has to be interpreted by bash. QLC+ does not run processes through bash commands. Also, I think the simple quote around

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audtool get-volume

are a miscopy, they should be backquotes. But this is another issue.

By the way, this looks more like a usage question rather than a issue report...

Maybe.



Please try this one:

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systemcommand:bash arg:-c arg:"audtool set-volume $(($(audtool get-volume) - 5))"

[mcallegari]

But it works. You can also replace "arg" with "hi" or "hello", it will work too. Should a github issue be opened for this ?

Ugh...yes please

Then have a look at #843 please

This does not work, because

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$((`audtool get-volume`))

is something that has to be interpreted by bash. QLC+ does not run processes through bash commands. Also, I think the simple quote around

Right. I'm wondering if the QProcess class can actually work like a proper shell. I'll check the docs when I have some time

[plugz]

Right. I'm wondering if the QProcess class can actually work like a proper shell. I'll check the docs when I have some time

No it can't. It's not a shell command interpreter. It simply runs a process.
And I think it's fine like this. Users can still use "bash -c" to run shell commands. Or even write the script in an external .sh file.

[mcallegari]

Right. I'm wondering if the QProcess class can actually work like a proper shell. I'll check the docs when I have some time

No it can't. It's not a shell command interpreter. It simply runs a process.
And I think it's fine like this. Users can still use "bash -c" to run shell commands. Or even write the script in an external .sh file.

Actually, you can pass the system environment to it:
http://doc.qt.io/qt-5/qprocess.html#set ... nvironment

In any case I agree regarding a shell script.
I would do something like

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setVolume.sh 5
setVolume.sh -5

[iamchrislaurie]

That is what I did in the end I created a shell file. I could not get the bash -c to work. This solution probably won't work in Windows.

One thing that would work for this use case is if the scripting allowed for the interim storage of the result of a systemcommand call - some like this

%v = systemcommand:audtool arg1:get-volume
systemcommand:audtool arg1:set-volume arg2:%v - 1

Not sure about how the syntax will work but that would give us the start of the capability to read and set dmx channel values via these variables.

[Stringfamily]

systemcommand:/bin/sh arg:/home/pi/PP-QLC-Lights/ShowVoxON.sh // copies show file with vocals to correct location


This is what in a few different versions I use to change audio files used in a show... works great. Attach it to a button and OSC command.