# Printer setup

In the modern world of linux, we use the CUPS printing system to interface with printers.

With modern printers, you usually don't even need drivers. This is known as "driverless printing".

Some older printers may need drivers in order for you to print to them, this will not be covered in this guide. The basic procedure is to look up the drivers for your printer and check if they are available in the repositories of your linux distribution. If you are unsure, you can install a group package with many drivers and hope that one of them works.

## Installation

The first step is installing CUPS. The following instructions were performed on arch linux, but the procedure is roughly the same on other distrubtions. (refer to your local wiki!).

`sudo pacman -S cups`

If you want to be able to "print" to PDF documents, aka save to PDF via the print dialog, you can also install the following package:

`sudo pacman -S cups-pdf`

Then enable the CUPS service. You can either enable the service directly, or use *socket activation*.

**A.** Socket activation: only starts the service when a program needs it.

`sudo systemctl enable cups.socket`

**B.** Enable service: the CUPS service is always active, even when no program has requested it.

`sudo systemctl enable --now cups.service`

## Configuration

Now that you have the printing service installed, you probably want to add some printers.

There are a few way of doing this. If your printer is parallel or USB, it should have been detected automatically (provided your system has the correct kernel modules loaded: lp, parport, parport_pc).
You can manage your printers in the CUPS web interface.

### CUPS web interface

By default, the CUPS configuration web interface can be accessed at [http://localhost:631/admin/](http://localhost:631/admin/).

If you use *socket activation*, you might need to start the service first: `sudo systemctl start cups.service`.

The interface is pretty self-explanatory. If something is unclear, you can read the [CUPS Documentation](https://github.com/OpenPrinting/cups/?tab=readme-ov-file).

Alternatively, there are multiple [GUI Applications](https://wiki.archlinux.org/title/CUPS#GUI_applications) that can be used for configuration instead.

### Adding network printers

If the address of the printer is known (and preferably static) you can add it manually via the web interface or a GUI application.

However, in most network environments you want to set up automatic discovery.

First, follow the steps in the *HostnameResolution* guide and come back once you have it set up.

After doing that, all you have to do is restart the CUPS service and hostname resolution should be working:

`sudo systemctl restart cups.service`

NOTE: If you want to share printer resources, or just interact with windows resources (SMB) in general, you can install the `samba` package (arch linux):

`sudo pacman -S samba`

### Setting up permissions

Normally only system administrators are allowed to manage things like printer queues.

You can add your usergroup to `/etc/cups/cups-files.conf`, but this is not recommended.

Instead, you should configure policy kit to allow passwordless authentication for printer actions.

First, make sure you have policy kit set up. Follow the *PolicyKit* guide for that.

Then, create a policy kit rule: `/etc/polkit-1/rules.d/49-allow-passwordless-printer-admin.rules`:

```
polkit.addRule(function(action, subject) { 
    if (action.id == "org.opensuse.cupspkhelper.mechanism.all-edit" && 
        subject.isInGroup("wheel")){ 
        return polkit.Result.YES; 
    } 
});
```

And that is permissions set up!

### Setting paper size

On arch linux, libpaper is installed with cups. If it wasn't installed, it is recommended to install it to be able to control paper configuration.

The arch package is `libpaper`.

By default, libpaper uses the "Letter" paper size. If you don't want to change this every time you want to print something,
you can edit `/etc/papersize` for systemwide configuration, and `$USER/.config/papersize` for user-specific configuration.

To see available sizes, you can either view `man 1 paper` or `paper --no-size --all`.

### Discovering printers on LDAP servers

In order to discover printers on LDAP servers, please follow "Adding network printers" and then enable `cups-browsed.service`.