Linux lpd Command with Practical Examples

Introduction

In this lab, we will explore the lpd (Line Printer Daemon) command, a key tool for managing print jobs in Linux. We will learn how to configure the lpd daemon, manage print jobs, and perform various printing-related tasks. The lab covers the introduction to the lpd command, configuring the lpd daemon, and managing print jobs with lpd. The steps provided include checking the status of the lpd service, creating and enabling new print queues, and using commands like lpstat and lprm to manage the printing process.

Linux Commands Cheat Sheet

Skills Graph

Introduction to the lpd Command

In this step, we will explore the lpd (Line Printer Daemon) command, which is a key tool for managing print jobs in Linux. The lpd command is responsible for handling the printing process, including accepting print requests, managing print queues, and communicating with printers.

First, let's check the status of the lpd service on our Ubuntu 22.04 Docker container:

sudo systemctl status lpd

Example output:

● lpd.service - LPD Line Printer Daemon
     Loaded: loaded (/lib/systemd/system/lpd.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2023-04-21 12:34:56 UTC; 1min 23s ago
   Main PID: 1234 (lpd)
     Tasks: 1 (limit: 4915)
    Memory: 1.1M
    CGroup: /system.slice/lpd.service
            └─1234 /usr/sbin/lpd

As we can see, the lpd service is active and running on our system. The lpd daemon is responsible for managing the printing process, including accepting print requests, managing print queues, and communicating with printers.

Next, let's explore some basic commands for interacting with the lpd service:

## List available print queues
sudo lpstat -a

## View the status of the print queue
sudo lpstat -t

## Cancel a print job
sudo lprm job_id

These commands allow you to view the available print queues, check the status of the print queue, and cancel a specific print job.

Configuring the lpd Daemon

In this step, we will learn how to configure the lpd (Line Printer Daemon) service on our Ubuntu 22.04 Docker container.

First, let's create a new print queue. We'll use the lpadmin command to create a new print queue named "myprinter":

sudo lpadmin -p myprinter -v file:/dev/null -P /usr/share/ppd/cups-pdf.ppd -E

This command creates a new print queue named "myprinter" and associates it with the CUPS-PDF virtual printer driver.

Next, let's enable the new print queue:

sudo enable-printer myprinter

Now, let's verify that the new print queue has been created and enabled:

sudo lpstat -a

Example output:

myprinter accepting requests since Mon 01 Jan 2001 12:00:00 AM UTC

The output shows that the "myprinter" queue is now accepting print requests.

To further configure the lpd service, we can edit the /etc/printcap file, which is the configuration file for the lpd service. This file contains information about the available print queues, their settings, and other configuration options.

Open the /etc/printcap file using the nano text editor:

sudo nano /etc/printcap

In the file, you can add or modify entries for your print queues. For example, you can set the default printer, configure printer options, or specify the location of the printer.

After making any changes, save the file and restart the lpd service:

sudo systemctl restart lpd

This will apply the new configuration changes to the lpd service.

Managing Print Jobs with lpd

In this final step, we will learn how to manage print jobs using the lpd command.

First, let's create a sample text file to print:

echo "This is a test print job." > ~/project/test_print.txt

Now, let's submit the file to the "myprinter" print queue:

lpr ~/project/test_print.txt

This will send the "test_print.txt" file to the "myprinter" print queue for printing.

To view the current print jobs in the queue, use the lpq command:

sudo lpq myprinter

Example output:

myprinter is ready
Rank   Owner   Job     File(s)                         Total Size
active labex   123     test_print.txt                  24 bytes

The output shows that the "test_print.txt" file is currently being printed as job 123.

If you need to cancel a print job, use the lprm command:

sudo lprm 123

This will cancel the print job with ID 123.

Finally, let's check the print queue again to verify that the job has been removed:

sudo lpq myprinter

Example output:

myprinter is ready
no entries

The output shows that the print queue is now empty, indicating that the print job has been successfully canceled.

Summary

In this lab, we explored the lpd (Line Printer Daemon) command, a key tool for managing print jobs in Linux. We learned how to check the status of the lpd service, list available print queues, view the status of the print queue, and cancel a specific print job. We then configured the lpd daemon by creating a new print queue and associating it with the CUPS-PDF virtual printer driver, and enabled the new print queue. These steps provide a solid foundation for managing printing processes on a Linux system.

Linux Commands Cheat Sheet