Hello Craig,
To install packages from sid or testing with apt, edit your sources.list file (either /etc/apt/sources.list or a file under /etc/apt/sources.list.d) and copy the line that lists "stable". change the copy to "testing" or "unstable".
BTW, you can do a partial upgrade to either sid or testing by:
1. adding entries for either (or both) of them to your sources.list. e.g.
deb http://your.nearest.debian.mirror/debian/ stable main non-free contrib deb http://your.nearest.debian.mirror/debian/ testing main non-free contrib deb http://your.nearest.debian.mirror/debian/ unstable main non-free contrib
2. and then adding the following to /etc/apt/apt.conf (or to a file under /etc/apt/apt.conf.d):
APT::Default-Release "stable";
That makes packages from sid or testing available, but they will NOT be installed unless you explicitly tell apt to install them with the '-t' (aka '--target-release') option. e.g.
apt-get update apt-get -V -d -u -t unstable install sane-utils libsane
That will verbosely show which packages *would* be upgraded and download them.
Done this, and "interesting" results. Will have to try the backport route. Unmet dependencies: libkf5coreaddons5 : Breaks : libkf5auth5 (< 5.54) but 5.28.0-2 is to be installed Breaks : libkf5globalaccel-bin (<5.54) but 5.28.0-2 is to be installed libkf5crash5 : Breaks : libkf5globalaccel-bin (<5.54) but 5.28.0-2 is to be installed
Verify that the command won't do anything unexpected (like removing other packages - such as your desktop environment - or upgrading 1000 other packages) and then run the same command without the "-V" or "-d" options to actually install them.
As a rule of thumb: if an 'apt-get -t unstable install' wants to remove any packages or upgrade/install lots of other packages, then abort the upgrade.
Will not force this. BTW. from the apt-get man page:
-t, --target-release, --default-release
This option controls the default input to the policy engine; it creates a default pin at priority 990 using the specified release string. This overrides the general settings in /etc/apt/preferences. Specifically pinned packages are not affected by the value of this option. In short, this option lets you have simple control over which distribution packages will be retrieved from. Some common examples might be -t '2.1*', -t unstable or -t sid. Configuration Item: APT::Default-Release; see also the apt_preferences(5) manual page.
NOTE: it is generally better to upgrade entirely to testing or sid (or backport a required package to stable) than it is to run a combination of stable + some packages from testing/unstable. You're far less likely to run into library quirks and version incompatibilities that way.
Was expecting that, but hoping maybe not.
Alternatively, download the debianised source for sane-utils and rebuild for debian 9. i.e. make your own backport.
That has potential, but would need the backport of the libsane as well. I am not yet sure of the development and build environment, nor whether I have the necessary installed yet.
Both the sane-utils and libsane packages are built from the same source package, "sane-backends".
BTW, if you use dpkg-buildpackage to build the packages, it will warn you if any build-dependencies are not met.
About to go looking at this. Now to sort out the best way to get the source package, and how to do the build, and whether I have the full toolchain (compiler, make etc) to do. I have seen bits and pieces on web pages, as well as your very good details, but it is still beyond prior experience. I am up for attempting to stretch what I can do. I have installed apt-src and now go looking for the right version of sane-backends and see whether I can build it.
If any of this is outside your comfort zone, then it would be better to just wait until either the new sane packages are in debian backports or until you upgrade to the next debian stable release. or ask someone you trust who runs debian stable to backport them for you.
You and Russell Coker are the ones I trust on competence, but both of you have a lot else to do, and may well not have a Debian 9.7 machine that you can do it on. My Debian 9.7 machine is currently up to date, but definitely learning and stretching. Now to sort out selecting the right dist for the apt-src command, hopefully follows the same pattern as the apt-get command.
craig
Regards, Mark Trickett