TIPS: Miscellaneous Tips

CUPS Debug Logging

Debug logging causes additional messages to be written to the CUPS error logs (usually in the /var/cups/error_log* directory). These messages are often important in diagnosing problems and bugs in Captdriver.

To switch on debug logging, run:

cupsctl --debug-logging

To switch it off, run:

cupsctl --no-debug-logging

There may be a delay when running these commands. If any of the commands fail with a Connection reset by peer error, try repeating the command after waiting a few seconds.

The cupsctl command should be available on systems where the CUPS development packages have been installed. The binary is usually found in /usr/sbin/.

CUPS USB Backend Quirks

The directory at /usr/share/cups/usb contains configuration files which selectively disables backend features for devices, or excludes them completely (by "blacklisting").

Devices are targeted in these configuration files by their USB vendor and product IDs. Instructions on how to use these files should be included in the first lines of org.cups.usb-quirks.

PROTIP: list product and vendor IDs of attached USB devices with lsusb.