update Zotero in ubuntu

This led to this forum post - http://forums.zotero.org/discussion/21759/update-failure-on-ubuntu-1110/ - and the idea that the problem was due to not having write access caused the problem. However, while granting write permissions to /opt and /opt/zotero was enough to download the update, it was not enough to install the update, and I had the error "The update could not be installed. Please make sure there are no other copies of Zotero running on your computer, and then restart Zotero to try again." My install is in /opt, simply using

# chmod -R o+w /opt/zotero /opt

finally solved the problem. After installing, I undid the procedure to return to the previous state with

# chmod -R o-w /opt/zotero /opt