In Inkscape, how do I add a white background in command line mode?

Question

in short, I tried

for f in `ls *.pdf`; do inkscape -z --export-background=ffffff --export-background-opacity=1.0 --export-plain-svg=${f}.svg $f; done

It throws no errors, produces SVG files, but doesn't add background to them. Does someone know what's wrong?

It's Inkscape 0.92.4

UPD thanks Billy Kerr for pointing towards the solution. I combined his suggestion with use of GNU sed to process many files automatically. It seems like meaningful data in SVG starts from <defs> tag, so I just add the rectangle before the first <defs occurrence:

for f in "*.pdf.svg"; do sed -i '0,/<defs/s/<defs/<rect width="100%" height="100%" fill="#ffffff"\/>\n  <defs/' $f; done

which means: sed, please find the first occurrence of a pattern (0,/pattern) and substitute it s/pattern/new string \n pattern/, writing to the same file (sed -i flag). It looks like a very ad hoc solution, but it works.

Answer 1

Inkscape has no background attribute as such, although it does have pagecolor which can be set in the document properties (it shows up as "background" in the UI, but appears as "pagecolor" in the XML). The problem however is that the pagecolor attribute is not supported in SVG and so it will be lost when you export as plain SVG.

Instead you could try editing the SVG in a text editor to add a white filled rectangle the same size as the canvas, and before (i.e. underneath) the artwork layer. Sorry, I don't know how to do that with the command line, but hopefully there's enough information here to help you work it out.

for example:

<rect width="100%" height="100%" fill="#ffffff"/>

Answer 2

Typing inkscape --help shows all the commands. One of which being:

 -b, --export-background=COLOR              Background color of exported
                                             bitmap (any SVG-supported color
                                             string)

As an example, I use LaTeX and other tools a lot of mathematics. A part of the workflow is converting images from SVG to PNG (where I explicitly need a white background). I often use a command like:

inkscape MyFile.svg -e MyFile.png -w 300 -b white

This simply converts to a png with a width of 300 and with a white background.

As an example, here is my original:

And here is an export with a RED background: