Scanners
Installing scanner support
Scanner support is provided by the SANE library. To enable scanner support, amend your system configuration like so:
/etc/nixos/configuration.nix
{
...
hardware.sane.enable = true; # enables support for SANE scanners
...
}
Users in the scanner group will gain access to the scanner, or the lp group if it’s also a printer. To add yourself to these groups, amend your system configuration as follows:
/etc/nixos/configuration.nix
{
...
users.users.YOURUSERNAME.extraGroups = [ "scanner" "lp" ];
...
}
 |
Tip
In order to affect your NixOS system by your nix-language-specific changes you must first evaluate it:
$ nixos-rebuild switch --use-remote-sudo |
| |
Tip
The detection of installed backends by SANE depends on the
LD_LIBRARY_PATH environment variable, which is set at login. You will need to logout and login again for backend changes to take effect after evaluation. |
Testing scanner support
To determine if your scanner is supported by SANE:
$ scanimage -L
If you can only see scanners when running as root, try adding the user to the scanner or lp either using the configuration given above, or using the following code (beware, don't forget to logout/login after running this command):
$ sudo usermod -a -G scanner,lp username
Supported backends
See the Supported Devices page to see if your scanner is supported. Some backends are proprietary and are not installed by default; see below. You may also be interested by "driverless" scanning (see below) if your scanner support the Apple AirScan and/or the Microsoft WSD, Apple maintains a list of compatible devices here.
Driverless Apple AirScan and Microsoft WSD
A large number of printers now support "driverless" scanning. As explained on the sane-airscan backend project:
Driverless scanning comes in two flavors:
- Apple AirScan or AirPrint scanning (official protocol name is eSCL)
- Microsoft WSD, or WS-Scan (term WSD means "Web Services for Devices)
This backend implements both protocols, choosing automatically between them. It was successfully tested with many devices from Brother, Canon, Dell, Kyocera, Lexmark, Epson, HP, Panasonic, Ricoh, Samsung and Xerox both in WSD and eSCL modes.
For eSCL devices, Apple maintains a comprehensive list of compatible devices, but please note, this list contains not only scanners and MFP, but pure printers as well.
To enable Apple AirScan/Microsoft WSD "driverless" scanning: use the sane-airscan drivers:
hardware.sane.extraBackends = [ pkgs.sane-airscan ];
If the scanner is an USB scanner, also set the following option:
services.ipp-usb.enable=true;
HP
hardware.sane.extraBackends = [ pkgs.hplipWithPlugin ];
Epson
If your scanner is listed as supported by the epkowa backend:
hardware.sane.extraBackends = [ pkgs.epkowa ];
Some other scanners (see list) need the utsushi backend:
hardware.sane.extraBackends = [ pkgs.utsushi ];
services.udev.packages = [ pkgs.utsushi ];
SnapScan firmware
Many scanners require firmware blobs which can be downloaded from the website of the scanner or extracted from the drivers they provide. Once you have the appropriate firmware you need to tell SANE where to find it in your configuration.nix:
{
hardware.sane.enable = true;
hardware.sane.drivers.scanSnap.enable = true;
# the below may be necessary
nixpkgs.config.sane.snapscanFirmware = pkgs.fetchurl {
# https://wiki.ubuntuusers.de/Scanner/Epson_Perfection/#Unterstuetzte-Geraete
url = "https://media-cdn.ubuntu-de.org/wiki/attachments/52/46/Esfw41.bin"; #Epson Perfection 2480
sha256 = "00cv25v4xlrgp3di9bdfd07pffh9jq2j0hncmjv3c65m8bqhjglq";
};
}
Brother
Brother currently provides four different scanner backends for various generations of its scanners. The newest (brscan4) is supported as a loadable submodule in NixOS. It can be activated by importing the appropriate file into /etc/nixos/configuration.nix:
{
...
imports = [
<nixpkgs/nixos/modules/services/hardware/sane_extra_backends/brscan4.nix>
./hardware-configuration.nix
];
...
}
Then just add a scanner in the sane module:
{
...
hardware = {
sane = {
enable = true;
brscan4 = {
enable = true;
netDevices = {
home = { model = "MFC-L2700DN"; ip = "192.168.178.23"; };
};
};
};
};
...
}
In some cases, configuration changes may not take effect until after a reboot.
GIMP support
To enable support for scanning in GIMP:
- You need to install a special version of xsane, which you can enable by amending /etc/nixos/configuration.nix as follows:
{ ... nixpkgs.config.packageOverrides = pkgs: { xsaneGimp = pkgs.xsane.override { gimpSupport = true; }; }; ... }
- Rebuild:
$ sudo nixos-rebuild switch
- Finally, you will need to manually create a symlink:
$ ln -s /run/current-system/sw/bin/xsane ~/.config/GIMP/2.10/plug-ins/xsane
Network scanning
If NixOs cannot find a scanner located on your network, you may be interested in adding in your configuration.nix:
{
...
services.avahi.enable = true;
services.avahi.nssmdns = true;
...
}
Currently (2017-08-16) the SANE backend does not support overriding according to 
nixpkgs issue #17411. The workaround for this is to download michaelrus's sane-extra-config.nix, copy it to /etc/nixos/sane-extra-config.nix and import it in /etc/nixos/configuration.nix as follows:
{
...
imports = [
...
./sane-extra-config.nix
...
];
...
hardware.sane.extraConfig."magicolor" = ''
net 10.0.0.30 0x2098
''; # Magicolor 1690mf
...
}
Using the scanner button
Many scanners feature a hardware button which makes for very convenient operation, especially in combination with an automated document processing system like paperless. NixOS includes the scanner button daemon scanbd which can be used for this purpose; however, its setup isn't terribly user friendly.
Basic scanbd configuration requires us to provide:
- a config file;
- a script to execute the scanning sequence;
- a systemd service that loads the config file, starts polling the scanner, and executes the script when it detects a button press.
| |
Tip
As scanbd continuously polls the scanner, it can't be used at the same time by SANE, which must be disabled.
|
There is a more advanced configuration which allows sharing the scanner with SANE frontends, but I haven't yet figured out how to set this up under NixOS (the config is a bit recursive).
Full documentation is in the project README.
kliu's blog includes in his writeup a nice script, bits of which have been cribbed here.
Here is a working derivation that dumps the scanned document into the paperless intake directory; you'll need to modify it to suit your own needs.
{ config, lib, pkgs, ... }:
with lib;
let
configDir = "/etc/scanbd";
saneConfigDir = "${configDir}/sane.d";
scanbdConf = pkgs.writeText "scanbd.conf"
''
global {
debug = true
debug-level = ${toString config.services.scanbd.debugLevel}
user = ${config.services.scanbd.user}
group = ${config.services.scanbd.group}
scriptdir = ${configDir}/scripts
pidfile = ${config.services.scanbd.pidFile}
timeout = ${toString config.services.scanbd.timeOut}
environment {
device = "SCANBD_DEVICE"
action = "SCANBD_ACTION"
}
multiple_actions = true
action scan {
filter = "^scan.*"
numerical-trigger {
from-value = 1
to-value = 0
}
desc = "Scan to file"
script = "scan.script"
}
${config.services.scanbd.extraConfig}
}
'';
scanScript = pkgs.writeScript "scanbd_scan.script"
''
#! ${pkgs.bash}/bin/bash
export PATH=${lib.makeBinPath [ pkgs.coreutils pkgs.sane-frontends pkgs.sane-backends pkgs.ghostscript pkgs.imagemagick ]}
set -x
date="$(date --iso-8601=seconds)"
filename="Scan $date.pdf"
tmpdir="$(mktemp -d)"
pushd "$tmpdir"
scanadf -d "$SCANBD_DEVICE" --source "ADF Duplex" --mode Gray --resolution 200dpi
# Convert any PNM images produced by the scan into a PDF with the date as a name
convert image* -density 200 "$filename"
chmod 0666 "$filename"
# Remove temporary PNM images
rm --verbose image*
# Atomic move converted PDF to destination directory
paperlessdir="/var/lib/paperless/consume"
cp -pv "$filename" $paperlessdir/"$filename".tmp &&
mv $paperlessdir/"$filename".tmp $paperlessdir/"$filename" &&
rm "$filename"
popd
rm -r "$tmpdir"
'';
in
{
###### interface
options = {
services.scanbd.enable = mkOption {
type = types.bool;
default = false;
description = ''
Enable support for scanbd (scanner button daemon).
<note><para>
If scanbd is enabled, then saned must be disabled.
</para></note>
'';
};
services.scanbd.user = mkOption {
type = types.str;
default = "scanner";
example = "";
description = ''
scanbd daemon user name.
'';
};
services.scanbd.group = mkOption {
type = types.str;
default = "scanner";
example = "";
description = ''
scanbd daemon group name.
'';
};
services.scanbd.extraConfig = mkOption {
type = types.lines;
default = "";
example = ''
device canon {
filter = "^genesys.*"
desc = "Canon LIDE"
action file {
filter = "^file.*"
desc = "File"
script = "copy.script"
}
}
'';
description = ''
Extra configuration lines included verbatim in scanbd.conf.
Use e.g. in lieu of including device-specific config templates
under scanner.d/
'';
};
services.scanbd.pidFile = mkOption {
type = types.str;
default = "/var/run/scanbd.pid";
example = "";
description = ''
PID file path.
'';
};
services.scanbd.timeOut = mkOption {
type = types.int;
default = 500;
example = "";
description = ''
Device polling timeout (in ms).
'';
};
services.scanbd.debugLevel = mkOption {
type = types.int;
default = 3;
example = "";
description = ''
Debug logging (1=error, 2=warn, 3=info, 4-7=debug)
'';
};
};
###### implementation
config = mkIf config.services.scanbd.enable {
users.groups.scanner.gid = config.ids.gids.scanner;
users.users.scanner = {
uid = config.ids.uids.scanner;
group = "scanner";
};
environment.etc."scanbd/scanbd.conf".source = scanbdConf;
environment.etc."scanbd/scripts/scan.script".source = scanScript;
environment.etc."scanbd/scripts/test.script".source = "${pkgs.scanbd}/etc/scanbd/test.script";
systemd.services.scanbd = {
enable = true;
description = "Scanner button polling service";
documentation = [ "https://sourceforge.net/p/scanbd/code/HEAD/tree/releases/1.5.1/integration/systemd/README.systemd" ];
script = "${pkgs.scanbd}/bin/scanbd -c ${configDir}/scanbd.conf -f";
wantedBy = [ "multi-user.target" ];
aliases = [ "dbus-de.kmux.scanbd.server.service" ];
};
}