A printer can be started for a disabled queue, in which case it will continue to print jobs in the queue until the queue is empty. In general, you have to have root privileges to use the lpc command. Ordinary users can use the lpc command to get printer status and to restart a hung printer only. Here is a summary of the lpc commands. Most of the commands takes a printer-name argument to tell on which printer to operate.
Users can still submit jobs if the queue's enabled.
Occasionally, the files that make up a job are not properly removed by LPD, particularly if there have been errors during printing or a lot of administrative activity. This command finds files that do not belong in the spooling directory and removes them. If the printer's started, it will continue to print any jobs remaining in the queue. Other users will not be able to submit jobs until you complete your testing and re-enable the queue with the enable command. Take a printer down.