Specifying network scanner with scanimage

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1

scanimage -L gives

device `v4l:/dev/video2' is a Noname HD Webcam: IR Camera virtual device
device `v4l:/dev/video0' is a Noname HD Webcam: HD Webcam virtual device
device `escl:http://[2a02:168:b9ec:0:da5d:e2ff:fe3e:921f]:8080' is a HP Color LaserJet MFP M277dw (gutenberg) platen,adf scanner

But, even though scainimage itself finds my local networked scanner (the last item in the above list) I miserably fail to find any variation on the information that scanimage gives me about the device, that is accepted as a value for scanimage --device-name.

In general, hp-scanning is the one thing that I have never managed to get to work on NixOS.

How can I make progress on this?

2

Adding pkgs.sane-airscan to hardware.sane.extraBackends results in one more line appearing in the output of scanimage -L:

device `v4l:/dev/video2' is a Noname HD Webcam: IR Camera virtual device
device `v4l:/dev/video0' is a Noname HD Webcam: HD Webcam virtual device
device `escl:http://[2a02:168:b9ec:0:da5d:e2ff:fe3e:921f]:8080' is a HP Color LaserJet MFP M277dw (gutenberg) platen,adf scanner
device `airscan:e0:HP Color LaserJet MFP M277dw (gutenberg)' is a eSCL HP Color LaserJet MFP M277dw (gutenberg) ip=2a02:168:b9ec:0:da5d:e2ff:fe3e:921f

and now

scanimage -d 'airscan:e0:HP Color LaserJet MFP M277dw (gutenberg)' -o scan.pdf

results in a scan of the document in the scanner appearing in scan.pdf.

This makes the scanner usable, though not conveniently (that long-winded name with space and parentheses in it is not user-friendly) and it’s puzzling that the equivalent does not work for the ecsl:... result.

3

if you only want to use the airscan scanner and never the escl scanner you can set
https://search.nixos.org/options?channel=23.11&show=hardware.sane.disabledDefaultBackends&from=0&size=50&sort=relevance&type=packages&query=sane+disable

hardware.sane.disabledDefaultBackends = [ "escl" ];

actually, you can probably also disable the v4l backend which detects webcams.

4

I was under the impression that airscan and escl were one and the same. The NixOS wiki scanners page seems to agree:

Apple AirScan or AirPrint scanning (official protocol name is eSCL)

so I’m confused as to why both airscan and ecsl appear in the output of scanimage -L, both referring to the same physical scanner.

On another machine which is on the same network to which I have copied the same configuration, scanimage -L doesn’t find the scanner at all!

I don’t really care whether I use ecsl or airscan as long as the scanner is usable. If it could be accessed using a more convenient specification than

-d 'airscan:e0:HP Color LaserJet MFP M277dw (gutenberg)'

that would be even better.

I still haven’t managed to get scanimage -d to understand the ecsl version, even though it is scanimage -L which tells me about its existence in the first place. All very confusing.

5

if you disable all backends but airscan, you only get one scanner, and you don’t have to specify -d anymore.

About the two backends: escl is builtin but less powerful than airscan, which is third party. Both can find the same scanner (but airscan can detect more).

6

Yes, that works on the first machine. Thanks!

The second one still doesn’t find the scanner :frowning:

7

maybe enabling avahi would fix that?

8

I already have

  services.avahi.enable  = true;
  services.avahi.nssmdns = true;
  services.avahi.publish.enable = true;
  services.avahi.publish.addresses = true;
  services.avahi.publish.userServices = true;