Since Ubuntu 7.10, a PDF printer has been installed by default. The behavior of this feature has changed from Ubuntu 7.10, instead of asking for a name and location for the PDF, Ubuntu 8.04 will guess a name for the document and place the file in a folder called PDF in your home directory.
I’d rather have PDFs just saved to my desktop. These are instructions for Ubuntu 8.04, previous versions of Ubuntu ignore this setting. Note that this is a system-wide setting.
Open the file /etc/cups/cups-pdf.conf as the root user: