arithmetic in Console Commands

Hey All,
Not sure if the Topic makes much sense, but the questions is this. I have a FvwmButton bar, where i want each individual button height to be 1/3 of the length.
I did a

   SetEnv button_height 32

any now i want to Module to startup and to be 3 times the height of each button wide. I tried

AddToFunc StartFunction
+ I Module FvwmButtons -g `PipeRead 'expr $[button_height]\*3'`x$[vp.height]-0+0 RightButtonBar

but it doesn’t work. It seems right to me, what I gathered from looking at other peoples .fvwm2rc files.
Thanks in Advance

You have things the wrong way around, anyway. You can’t just come in and out of a piperead and assume everything is preprocessed whence it left off – so in this instance, you have two options:

  1. Dynamically create a variable containing the actual geometry.
  2. Put the Module startup in piperead.

I’d go with 2., myself:

+ I PipeRead 'echo "Module FvwmButtons -g $(($[button_height]*3))x$[vp.height]-0+0 RightButtonBar"'

Or variations thereof. I am not in a means to test that.

– Thomas Adam.

ah, that worked great, i must have misunderstood the syntax of PipeRead. Thanks