[gentoo-user] insane backends

[gentoo-user] insane backends

[Philip Webb]

'sane-backends-1.0.27' just stabilised, so I updated to it.
Previously I had selected  4  items from the list in SANE_BACKENDS,
which is shown by 'emerge', ie 'epson epson2 plustek plustek_pp'.
My scanner is an 'Epson V550 Photo'.

Wanting to test which of the  4  items above was needed, I tried each.
Inadvertently, I tried emerging 'sane-backends' with none included
& discovered that my scanner still works regardless !

There is a file  /etc/hotplug/usb/libsane.usermap , which lists scanners,
& I have the line under 'V550' enabled.

What is the purpose of the long list of SANE_BACKENDS,
if Xsane finds the correct driver with none enabled ?

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca

Re: [gentoo-user] insane backends

[Neil Bothwick]

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On Sun, 29 Oct 2017 22:39:31 -0400, Philip Webb wrote:

> 'sane-backends-1.0.27' just stabilised, so I updated to it.
> Previously I had selected  4  items from the list in SANE_BACKENDS,
> which is shown by 'emerge', ie 'epson epson2 plustek plustek_pp'.
> My scanner is an 'Epson V550 Photo'.
> 
> Wanting to test which of the  4  items above was needed, I tried each.
> Inadvertently, I tried emerging 'sane-backends' with none included
> & discovered that my scanner still works regardless !

ISTR that with use_expanded variables like this, if you don't set the
variable then all options are enabled, so you've just built an
un-gentoolike version that works everywhere.

You could check this by using qlist to see what has been installed with
and without SANE_BACKENDS set.


-- 
Neil Bothwick

In plumbing, a straight flush is better than a full house.

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Re: [gentoo-user] insane backends

[Philip Webb]

171030 Neil Bothwick wrote:
> On Sun, 29 Oct 2017 22:39:31 -0400, Philip Webb wrote:
>> 'sane-backends-1.0.27' just stabilised, so I updated to it.
>> Previously I had selected  4  items from the list in SANE_BACKENDS,
>> which is shown by 'emerge', ie 'epson epson2 plustek plustek_pp'.
>> My scanner is an 'Epson V550 Photo'.
>> 
>> Wanting to test which of the  4  items above was needed, I tried each.
>> Inadvertently, I tried emerging 'sane-backends' with none included
>> & discovered that my scanner still works regardless !
> ISTR that with use_expanded variables like this,
> if you don't set the variable then all options are enabled,
> so you've just built an un-Gentoolike version that works everywhere.

That doesn't matter much beyond compile time, which is not excessive :
Xsane will interrogate the scanner & when it's told it's an Epson V550
it will load the appropriate driver & go from there.
From the point of view of system maintenance,
it's much simpler to let it do that than try to pick out the driver myself.

> You could check this by using qlist
> to see what has been installed with and without SANE_BACKENDS set.

'qlist sane-backends' doesn't show anything like that.

Thanks for the explanation.

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca

Re: [gentoo-user] insane backends

[Neil Bothwick]

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On Tue, 31 Oct 2017 22:19:41 -0400, Philip Webb wrote:

> 171030 Neil Bothwick wrote:
> > ISTR that with use_expanded variables like this,
> > if you don't set the variable then all options are enabled,
> > so you've just built an un-Gentoolike version that works everywhere.  
> 
> That doesn't matter much beyond compile time, which is not excessive :
> Xsane will interrogate the scanner & when it's told it's an Epson V550
> it will load the appropriate driver & go from there.
> From the point of view of system maintenance,
> it's much simpler to let it do that than try to pick out the driver
> myself.

That's a fair point, as always with Gentoo the choice is yours.
 
> > You could check this by using qlist
> > to see what has been installed with and without SANE_BACKENDS set.  
> 
> 'qlist sane-backends' doesn't show anything like that.

qlist sane-backends | grep usr/lib64/sane

lists the installed backends here.


-- 
Neil Bothwick

668 - The neighbour of the beast.

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Re: [gentoo-user] insane backends

[Philip Webb]

171101 Neil Bothwick wrote:
> 'qlist sane-backends | grep usr/lib64/sane'
> lists the installed backends here.

Here all I get is :

  root:552 log> qlist sane-backends | grep usr/lib64/sane
    /usr/lib64/sane/libsane-dll.so.1
    /usr/lib64/sane/libsane-dll.so
    /usr/lib64/sane/libsane-dll.so.1.0.27
  root:553 log>

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca

Re: [gentoo-user] insane backends

[Neil Bothwick]

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On Wed, 1 Nov 2017 14:26:15 -0400, Philip Webb wrote:

> > 'qlist sane-backends | grep usr/lib64/sane'
> > lists the installed backends here.  
> 
> Here all I get is :
> 
>   root:552 log> qlist sane-backends | grep usr/lib64/sane
>     /usr/lib64/sane/libsane-dll.so.1
>     /usr/lib64/sane/libsane-dll.so
>     /usr/lib64/sane/libsane-dll.so.1.0.27
>   root:553 log>

Which looks like you have no backends installed, so why does it work?


-- 
Neil Bothwick

When you choke a smurf, what color does it turn?

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Re: [gentoo-user] insane backends

[Philip Webb]

171101 Neil Bothwick wrote:
> On Wed, 1 Nov 2017 14:26:15 -0400, Philip Webb wrote:
>> 'qlist sane-backends | grep usr/lib64/sane'
>> Here all I get is :
>>   root:552 log> qlist sane-backends | grep usr/lib64/sane
>>     /usr/lib64/sane/libsane-dll.so.1
>>     /usr/lib64/sane/libsane-dll.so
>>     /usr/lib64/sane/libsane-dll.so.1.0.27
>>   root:553 log>
> Which looks like you have no backends installed, so why does it work?

  root:560 lib64> ls -l sane
    lrwxrwxrwx 1 root root     21 Oct 29 22:23 libsane-dll.so -> libsane-dll.so.1.0.27
    lrwxrwxrwx 1 root root     21 Oct 29 22:23 libsane-dll.so.1 -> libsane-dll.so.1.0.27
    -rwxr-xr-x 1 root root  35248 Oct 29 22:23 libsane-dll.so.1.0.27
    -rw-r--r-- 1 root root    955 Jun 20  2016 libsane-epkowa.la
    lrwxrwxrwx 1 root root     24 May  5 18:06 libsane-epkowa.so.1 -> libsane-epkowa.so.1.0.15
    -rw-r--r-- 1 root root 295080 Jun 20  2016 libsane-epkowa.so.1.0.15
  root:561 lib64>

There is a driver left from the previous update.

Any explanation why it's still there ?

Anyway clearly, your previous explanation
-- that if no backend is specified, all are enabled -- was off-target (smile).

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca

Re: [gentoo-user] insane backends

[Neil Bothwick]

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On Wed, 1 Nov 2017 17:28:41 -0400, Philip Webb wrote:

> 171101 Neil Bothwick wrote:
> > On Wed, 1 Nov 2017 14:26:15 -0400, Philip Webb wrote:  
> >> 'qlist sane-backends | grep usr/lib64/sane'
> >> Here all I get is :
> >>   root:552 log> qlist sane-backends | grep usr/lib64/sane
> >>     /usr/lib64/sane/libsane-dll.so.1
> >>     /usr/lib64/sane/libsane-dll.so
> >>     /usr/lib64/sane/libsane-dll.so.1.0.27
> >>   root:553 log>  
> > Which looks like you have no backends installed, so why does it
> > work?  
> 
>   root:560 lib64> ls -l sane
>     lrwxrwxrwx 1 root root     21 Oct 29 22:23 libsane-dll.so ->
> libsane-dll.so.1.0.27 lrwxrwxrwx 1 root root     21 Oct 29 22:23
> libsane-dll.so.1 -> libsane-dll.so.1.0.27 -rwxr-xr-x 1 root root  35248
> Oct 29 22:23 libsane-dll.so.1.0.27 -rw-r--r-- 1 root root    955 Jun
> 20  2016 libsane-epkowa.la lrwxrwxrwx 1 root root     24 May  5 18:06
> libsane-epkowa.so.1 -> libsane-epkowa.so.1.0.15 -rw-r--r-- 1 root root
> 295080 Jun 20  2016 libsane-epkowa.so.1.0.15 root:561 lib64>
> 
> There is a driver left from the previous update.
> 
> Any explanation why it's still there ?

Something broke...[1]

> Anyway clearly, your previous explanation
> -- that if no backend is specified, all are enabled -- was off-target
> (smile).

It was a suggestion not an explanation, I did prefix it with ISTR ;-)
Reading the ebuild now, it is clear that one specified backends are
installed.

 [1] do you really think I'm going to say anything more specific
than that now :P


-- 
Neil Bothwick

Talk is cheap because supply exceeds demand.

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Re: [gentoo-user] insane backends

[Philip Webb]

Further to the thread re mysterious behaviour of 'sane-backends',
I remembered what happened when I set my new scanner up earlier in 2017.

There is no driver in 'sane-backends', because it contains a binary blob.
You have to download an appropriate pkg for the V550 from Epson,
which provides installers for Debian or RPM.
Presumably one of those worked with Gentoo
& that's where the 'epkowa' driver came from in  /usr/lib64/sane/ .

So relieved that I'd got it working, I failed to update my notes,
which I've now done.  Thanks for Neil's suggestions.

-- 
========================,,============================================
SUPPORT     ___________//___,   Philip Webb
ELECTRIC   /] [] [] [] [] []|   Cities Centre, University of Toronto
TRANSIT    `-O----------O---'   purslowatchassdotutorontodotca