How to clear CUPS spool automatically?

Question

When printing to HP printer, I noticed that all printed files are saved to /var/spool/cups.

Is it possible to avoid this from a privacy perspective?

Answer 1

Deleting the job files can be done with the cancel(1) command.

$ cancel -a -x

will remove all job files for the current user.

If you want CUPS to not save them at all, the PreserveJobFiles directive can be added to cupsd.conf as described here:

https://opensource.apple.com/source/cups/cups-372/cups/doc/help/ref-cupsd-conf.html.in

(somewhere along the line Apple has stopped including this documentation file at opensource.apple.com, this seems to be the last version the file exists for, although CUPS itself is a higher version now)

Answer 2

Enable cups web interface to edit the cups.conf file in an easy way:

• Open the terminal
• Paste in cupsctl WebInterface=yes and press enter

Go to the Cups web page at http://localhost:631/printers/ and see your installed printers.

• In the top menu click 'Administration'

• On the right you find a button 'Edit Configuration File'

• There you can add the information to delete the history files. Mine looks like this (the 1800 makes the deamon wait for half an hour before deleting):

  PreserveJobFiles 1800
  PreserveJobHistory 1800
  

• Click "Save Changes" and enter username/password of an admin user when prompted.

For more information see https://www.cups.org/doc/man-cupsd.conf.html

Answer 3

From the blog of the OP:

echo "PreserveJobHistory Off" | sudo tee -a /etc/cups/cupsd.conf
sudo launchctl unload /System/Library/LaunchDaemons/org.cups.cupsd.plist
sudo launchctl load /System/Library/LaunchDaemons/org.cups.cupsd.plist

Unfortunately, /etc/cups/cupsd.conf sometimes gets overwritten during a macOS update. I have

grep -qe '^PreserveJobHistory Off$' /etc/cups/cupsd.conf || echo 'WARNING: CUPS history ENABLED'

in the startup file of the shell I use to warn me if this happens.