11.5 Using Printers

11.5.1 Printing Jobs

To print files, type:

    % lpr filename ...

This prints each of the listed files to the default printer. If you list no files, lpr(1) reads data to print from standard input. For example, this command prints some important system files:

    % lpr /etc/host.conf /etc/hosts.equiv

To select a specific printer, type:

    % lpr -P printer-name filename ...

This example prints a long listing of the current directory to the printer named rattan:

    % ls -l | lpr -P rattan

Because no files were listed for the lpr(1) command, lpr read the data to print from standard input, which was the output of the ls -l command.

The lpr(1) command can also accept a wide variety of options to control formatting, apply file conversions, generate multiple copies, and so forth. For more information, see the section Printing Options.

11.5.2 Checking Jobs

When you print with lpr(1), the data you wish to print is put together in a package called a ``print job'', which is sent to the LPD spooling system. Each printer has a queue of jobs, and your job waits in that queue along with other jobs from yourself and from other users. The printer prints those jobs in a first-come, first-served order.

To display the queue for the default printer, type lpq(1). For a specific printer, use the -P option. For example, the command

    % lpq -P bamboo

    bamboo is ready and printing
    Rank   Owner    Job  Files                              Total Size
    active kelly    9    /etc/host.conf, /etc/hosts.equiv   88 bytes
    2nd    kelly    10   (standard input)                   1635 bytes
    3rd    mary     11   ...                                78519 bytes

This shows three jobs in the queue for bamboo. The first job, submitted by user kelly, got assigned ``job number'' 9. Every job for a printer gets a unique job number. Most of the time you can ignore the job number, but you will need it if you want to cancel the job; see section Removing Jobs for details.

Job number nine consists of two files; multiple files given on the lpr(1) command line are treated as part of a single job. It is the currently active job (note the word active under the ``Rank'' column), which means the printer should be currently printing that job. The second job consists of data passed as the standard input to the lpr(1) command. The third job came from user mary; it is a much larger job. The pathname of the file she is trying to print is too long to fit, so the lpq(1) command just shows three dots.

The very first line of the output from lpq(1) is also useful: it tells what the printer is currently doing (or at least what LPD thinks the printer is doing).

The lpq(1) command also support a -l option to generate a detailed long listing. Here is an example of lpq -l:

    waiting for bamboo to become ready (offline ?)
    kelly: 1st               [job 009rose]
           /etc/host.conf                    73 bytes
           /etc/hosts.equiv                  15 bytes
    
    kelly: 2nd               [job 010rose]
           (standard input)                  1635 bytes
    
    mary: 3rd                                [job 011rose]
          /home/orchid/mary/research/venus/alpha-regio/mapping 78519 bytes

11.5.3 Removing Jobs

If you change your mind about printing a job, you can remove the job from the queue with the lprm(1) command. Often, you can even use lprm(1) to remove an active job, but some or all of the job might still get printed.

To remove a job from the default printer, first use lpq(1) to find the job number. Then type:

    % lprm job-number

To remove the job from a specific printer, add the -P option. The following command removes job number 10 from the queue for the printer bamboo:

    % lprm -P bamboo 10

The lprm(1) command has a few shortcuts:

Just use the -P option with the above shortcuts to operate on a specific printer instead of the default. For example, the following command removes all jobs for the current user in the queue for the printer named rattan:

    % lprm -P rattan -

11.5.4 Beyond Plain Text: Printing Options

The lpr(1) command supports a number of options that control formatting text, converting graphic and other file formats, producing multiple copies, handling of the job, and more. This section describes the options.

    % lpr -P bamboo -d fish-report.dvi

    % zcat /usr/share/man/man1/ls.1.gz | troff -t -man | lpr -t

11.5.5 Administrating Printers

As an administrator for your printers, you have had to install, set up, and test them. Using the lpc(8) command, you can interact with your printers in yet more ways. With lpc(8), you can

• Start and stop the printers

• Enable and disable their queues

• Rearrange the order of the jobs in each queue.

First, a note about terminology: if a printer is stopped, it will not print anything in its queue. Users can still submit jobs, which will wait in the queue until the printer is started or the queue is cleared.

If a queue is disabled, no user (except root) can submit jobs for the printer. An enabled queue allows jobs to be submitted. 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(8) command. Ordinary users can use the lpc(8) command to get printer status and to restart a hung printer only.

Here is a summary of the lpc(8) commands. Most of the commands take a printer-name argument to tell on which printer to operate. You can use all for the printer-name to mean all printers listed in /etc/printcap.

lpc(8) accepts the above commands on the command line. If you do not enter any commands, lpc(8) enters an interactive mode, where you can enter commands until you type exit, quit, or end-of-file.