With "foo.svg" as the image to edit:
inkscape --verb=EditSelectAll --verb=AlignHorizontalCenter --verb=AlignVerticalCenter --verb=FileSave --verb=FileQuit foo.svg
To edit all svg images in the current directory:
inkscape --verb=EditSelectAll --verb=AlignHorizontalCenter --verb=AlignVerticalCenter --verb=FileSave --verb=FileClose *.svg
But this second command opens a ton of windows, which will make your computer crash if you're editing too many images. For Linux only, this command will work better:
for img in *.svg; do inkscape --verb=EditSelectAll --verb=AlignHorizontalCenter --verb=AlignVerticalCenter --verb=FileSave --verb=FileQuit $img ; done
For the above command, if any of the files are symlinks, Inkscape will edit the target file that the symlink points to. If you don't want Inkscape to do this, you can filter out any symlinks with this command:
for img in *.svg; do if [[ $(readlink $img) == "" ]] ; then inkscape --verb=EditSelectAll --verb=AlignHorizontalCenter --verb=AlignVerticalCenter --verb=FileSave --verb=FileQuit $img ; fi ; done
While I'm at it, I might as well post the bash script I made for this:
#!/bin/bash
# inkscape-center <file-or-directory>...
_analyse() {
if [ -d "${1}" ] ; then
_centerAll "${1}" ;
else
_center "${1}" ;
fi
}
_centerAll() {
cd "${1}" ;
for img in *.svg; do
_filterSyms "${img}" ;
done
}
_filterSyms() {
if [[ $(readlink "${1}") == "" ]] ; then
_center "${1}"
fi
}
_center() {
inkscape --verb=EditSelectAll --verb=AlignHorizontalCenter --verb=AlignVerticalCenter --verb=FileSave --verb=FileQuit "${1}"
}
for arg ; do
_analyse "${arg}" ;
done
I called it inkscape-center
and run it like this:
inkscape-center <file-or-directory>
It takes as many arguments as you want, so you can do something like this:
inkscape-center 1st.svg 2nd.svg 3rd.svg 4th.svg
Be careful- If you specify a directory instead of a file, it'll edit every svg file in that directory.