Ubuntu > Filter directory /usr/lib/cups/filter for printer "<yourprinter>" is not owned by root.

Problem

You receive the following error status message for a printer, once it is installed (e.g. in the "Print" window).

Filter directory /usr/lib/cups/filter for printer "" is not owned by root. 

You may also see "cups-insecure-filter". 

Solution

Execute the following commands, to change ownership back to root. 

1. sudo chown -hR root:root /usr/lib/cups/filter/* 
2. sudo chown -hR root:root /usr/lib/cups/backend/* 
3. service cups restart 

Your printer should now no longer display the message. (May require closing and reopening the "Print" window). 

See also:
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/436544

Ubuntu > Install Canon Pixma MX870 i386 drivers on amd64

Problem

Canon only provide i386 drivers for the PIXMA MX870 All-In-One Printer on their Australian website.

These work fine with amd64, but just need the scripts to be tweaked to allow it (very easy to do).

Solution

Ensure you have the latest versions for the following applications:

$ apt-show-versions | grep -E "libcups2|libcupsys2|libc6|libpopt0"

e.g.
libc6/natty uptodate 2.13-0ubuntu13
libc6-dev/natty uptodate 2.13-0ubuntu13
libc6-i386/natty uptodate 2.13-0ubuntu13
libcups2/natty-security uptodate 1.4.6-5ubuntu1.4
libpopt0/natty uptodate 1.16-1

Follow these steps:

1. Download the MX870 series IJ Printer Driver Ver. 3.30 for Linux (debian Packagearchive)
2. Extract the cnijfilter-mx870series-3.30-1-i386-deb.tar.gz into a directory
1. Nautilus > right-click > Extract Here
2. Command line > tar -xvzf cnijfilter-mx870series-3.30-1-i386-deb.tar.gz -C /your/target/dir
3. Comment out the "i686" lines in the <extracteddir>/install.sh, as per the instructions here.
4. Update all <extracteddir>/packages/*.deb packages by running repackage.sh (see below), and removing the line beginning with "Dependency: ..." during the "vi" step.
1. e.g. ./repackage.sh <package>.deb
5. Run <extracteddir>/install.sh

repackage.sh

#!/bin/bash
PACKAGE=${1}
dpkg -x $PACKAGE common
dpkg --control $PACKAGE
vi DEBIAN/control
cp -a DEBIAN/ common/
dpkg -b common $PACKAGE
rm -rf common DEBIAN

See also:
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/701856/comments/20
http://ubuntuforums.org/showthread.php?t=1475336