Recently I was indoctrinated into the world of 6m EME when a few club members and I decided to give it a try on something of a whim. With a bit of encouragement from Lance W7GJ we raided and cherry picked our way through a few fellow club members shacks and sheds and pieced together a “small” portable 6m EME station. You can read about the activation on our club website once it’s published (click). The picture below speaks volumes;

While looking at various Apps and trying to work out how this EME thing works, I discovered MoonSked written by David GM4JJJ.

At first glance it appeared to be a cross platform application that would help me plan and understand how this EME thing works without wasting too many late nights outside. What I liked most is I could run it on both Windows or Linux. My main computer in the shack still runs Windows (for reasons), however for laptop(s) and servers I prefer various flavours of Linux. So the installation of MoonSked on my main shack computer was straight forward, however things rapidly fell apart when I tried the same on my Laptop that runs Ubuntu 18.04LTS. I downloaded the zip file, placed it in my home directory and then tried to run it, sigh it didn’t work.

After a quick check of the website I noticed the last version of Ubuntu that MoonSked was built to run on was 9.10 (karmic koala) which went end of life years ago (2013). Being a binary distribution means recompiling and linking this against 64-bit libraries was not an option, sigh; we had to do this the old fashioned hard way.

So having grown up using Linux for more years than I’d care to admit I had a fair idea that this would be the classic “shared library dependency problem”. I wasn’t to be disappointed and even learnt a little about how the new linux multiarch (well new to me) system worked.

So the crux of the problem was MoonSked was compiled against 32-bit binary libraries and my Ubuntu 18.04LTS distro is entirely 64-bit. It is little wonder that MoonSked couldn’t run. So the place to start with any dependency problem is the infamous ‘ldd utility’. Let’s poke inside MoonSked and see what libraries are under the hood;

legend@HP-ShackBook:~/MoonSked$ ldd MoonSked
   linux-gate.so.1 (0xf7f48000)
   libgtk-x11-2.0.so.0 => not found
   libgdk-x11-2.0.so.0 => not found
   libgmodule-2.0.so.0 => not found
   libglib-2.0.so.0 => not found
   libgthread-2.0.so.0 => not found
   libgobject-2.0.so.0 => not found
   libgdk_pixbuf-2.0.so.0 => not found
   libpango-1.0.so.0 => not found
   libpangocairo-1.0.so.0 => not found
   libpangoft2-1.0.so.0 => not found
   libpthread.so.0 => /lib32/libpthread.so.0 (0xf7f07000)
   libdl.so.2 => /lib32/libdl.so.2 (0xf7f02000)
   libXi.so.6 => not found
   libXext.so.6 => not found
   libX11.so.6 => not found
   libstdc++.so.6 => /usr/lib32/libstdc++.so.6 (0xf7d7c000)
   libm.so.6 => /lib32/libm.so.6 (0xf7cb1000)
   libgcc_s.so.1 => /usr/lib32/libgcc_s.so.1 (0xf7c93000)
   libc.so.6 => /lib32/libc.so.6 (0xf7aba000)
   /lib/ld-linux.so.2 (0xf7f4a000)
   libcairo.so.2 => not found

Ok so there are a few libraries missing and thankfully I can see some of the lib32 libraries are being found. What is not immediately apparent is that 32-bit libraries can be installed separately and sit alongside the very same 64-bit libraries. The multiarch features of the latest linux kernel and GNU tools is what confuses MoonSked trying to find it’s libraries. So to get MoonSked we need to solve the shared library dependencies separately. So watch the following carefully.

We start by double checking that we are in fact running a full 64-bit system;

legend@HP-ShackBook:~/MoonSked$ uname -m
   x86_64
legend@HP-ShackBook:~/MoonSked$ dpkg --print-architecture
   amd64

Excellent the kernel is 64-bit and we are using the 64-bit package repository that should be linked against 64-bit libraries. Now we check the following;

expert@HP-ShackBook:~/MoonSked$ dpkg --print-foreign-architectures
   i386

Ah Ha ! This is excellent as it means that we can install the 32-bit libraries with the dpkg/apt tools without having to configure dpkg. If you find that i386 isn’t defined as a foreign architecture you’ll need to use dpkg to enable it. There are plenty of websites on the net that can assist here (YMMV), Ubuntu 18.04LTS comes pre-configured for 32-bit and 64-bit multiarch out of the box.

So now we can simply use apt-get to install the dependencies. I simply use a process of elimination to work out what is missing. First I’d use apt-cache and the name of the shared lib to search for library names or resort to the internet, then I’d use apt-get to install it and then re-run ldd again to see the result. The following line works well when the output from ‘ldd’ gets more than a page or two;

$ ldd MoonSked | grep "not found"

This will basically print out any library dependency that was not found to the display. Slowly but surely you work your way through to the end of your list, making notes as you go for your blog (*grin*). Rather than document all of the above steps I’ll just give you the short list;

sudo apt-get install libc6:i386 libpango-1.0:i386 libcairo2:i386 libpangocairo-1.0:i386 libgtk2.0-0:i386 libcanberra-gtk-module:i386 libatk-adaptor:i386 gtk2-engines-murrine:i386 libdlm3:i386

Now the observant will notice at the end of each package is a colon and i386. This tells apt/dpkg to install the 32-bit library and not the default 64-bit package. Depending on what apps you have on your linux machine already some of these packages may already be installed and up to date. If you do find this is the case then simply drop the name off the list above and keep trying.

As I wrote at the very beginning of this post, these are the steps that worked for me on my Ubuntu 18.04LTS installation. I’m hoping that the process used to seek and destroy the missing dependencies makes sense it’s certainly not the only way to do it, works for me YMMV.

At least now I can fire up MoonSked on Ubuntu 18.04LTS and continue my 6m EME experiments. Thanks again to David GM4JJJ for writing MoonSked !