According to CUPS documentation, the standard config places cache files in /var/spool/cups/cache and print jobs in /var/spool/cups. I'd imagine the best strategy is either of the following:
- Clear it with specific CUPS commands. Unfortunately there's not a builtin command to clear the cache; only enabling/disabling specific print queues and removing specific print jobs seem to be available.
Use lpq (to view the queues), lprm, and cancel, or the web interface, to view current jobs and remove them.
cancel -a should cancel all jobs on all queues.
If your system is hosed by defined printers and queues, deleting those objects may help. Use lpadmin or the web interface to manage defined printers.
- Clear it manually, by:
- stopping CUPS (eg,
sudo service cups stop),
- removing files manually, and
- restarting CUPS (eg,
sudo service cups start).
This long thread suggests that /var/spool/cups contains completed print jobs while /var/spool/cups/tmp contains in-progress jobs. One post to that thread suggests running
sudo rm -r /var/spool/cups in step 2.2 above. Steps 2.1 and 2.3 show Ubuntu commands for stopping and starting services; other OS's will vary.
If you really need to delete cache files in /var/cache/cups, you will probably need to use the manual method.