[mali]

I've been building 'next' on Linux Mint 17.3 for some time now. No problems.  I was unable to get bluetooth to work though.  So I installed LM 18 and was (with a little tweaking) able to get a reliable bluetooth connection.  I decided to build from scratch but have run into a problem with the QT56 stuff.  Is this my problem or is the Qt56 stuff really missing in repository ppa:librepilot/tools?

Never mind. Went back to LM 17.3.  I need a GCS more than bluetooth I guess.  Something changed in LM 18 preventing getting the QT56 stuff.  If anyone figures it out please drop me a note how you did it.

[TheOtherCliff]

I'm running Mint Mate 17.2.  There is a manual "system wide" install procedure documented in relation to 32 bit IIRC.  I did that, and each time I start a new terminal I run:

source  /opt/qt56/bin/qt56-env.sh

But I think that is not supposed to be required any more?

[mali]

Under Linux Mint 18 'Sarah' Cinnamon 64 bit this is the output of some of the commands (taken from Linux - Building and Packaging in the docs).  Under LM 17.3 everything works as expected, but under LM 18 the QT56 stuff can't be located and, of course, there is no directory created /opt/qt56.  Here it is, maybe someone will see what the problem is.

greg@LinuxMacbook ~/code/librepilot $ git checkout next
Already on 'next'
Your branch is up-to-date with 'origin/next'.
greg@LinuxMacbook ~/code/librepilot $ sudo add-apt-repository ppa:librepilot/tools -y
[sudo] password for greg:
You are about to add the following PPA:
 Build dependencies for LibrePilot
 More info: https://launchpad.net/~librepilot/+archive/ubuntu/tools
Executing: /tmp/tmp.T41hxxEEkt/gpg.1.sh --keyserver
hkp://keyserver.ubuntu.com:80
--recv-keys
45DC3732
gpg: requesting key 45DC3732 from hkp server keyserver.ubuntu.com
gpg: key 45DC3732: public key "Launchpad PPA for LibrePilot" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
greg@LinuxMacbook ~/code/librepilot $ sudo apt-get update -q
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Get:2 http://ppa.launchpad.net/librepilot/tools/ubuntu xenial InRelease [18.1 kB]
Hit:3 http://archive.ubuntu.com/ubuntu xenial InRelease
Hit:4 http://archive.canonical.com/ubuntu xenial InRelease
Get:5 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [94.5 kB]
Hit:6 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Get:7 http://ppa.launchpad.net/librepilot/tools/ubuntu xenial/main Sources [1,088 B]
Get:8 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [248 kB]
Get:9 http://ppa.launchpad.net/librepilot/tools/ubuntu xenial/main amd64 Packages [2,128 B]
Get:10 http://ppa.launchpad.net/librepilot/tools/ubuntu xenial/main i386 Packages [2,132 B]
Get:11 http://ppa.launchpad.net/librepilot/tools/ubuntu xenial/main Translation-en [908 B]
Get:12 http://archive.ubuntu.com/ubuntu xenial-updates/main i386 Packages [244 kB]
Get:13 http://archive.ubuntu.com/ubuntu xenial-updates/main Translation-en [98.1 kB]
Get:14 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages [152 kB]
Get:15 http://archive.ubuntu.com/ubuntu xenial-updates/universe i386 Packages [149 kB]
Get:16 http://archive.ubuntu.com/ubuntu xenial-updates/universe Translation-en [74.9 kB]
Ign:17 http://packages.linuxmint.com sarah InRelease
Hit:18 http://packages.linuxmint.com sarah Release
Fetched 1,179 kB in 5s (216 kB/s)
Reading package lists...
greg@LinuxMacbook ~/code/librepilot $ sudo apt-get install -y libudev-dev \
> libusb-1.0-0-dev \
> libsdl1.2-dev \
> python \
> libopenscenegraph-dev \
> qt56-meta-minimal \
> qt56svg \
> qt56script \
> qt56serialport \
> qt56multimedia \
> qt56translations \
> qt56tools \
> qt56quickcontrols
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package qt56-meta-minimal
E: Unable to locate package qt56svg
E: Unable to locate package qt56script
E: Unable to locate package qt56serialport
E: Unable to locate package qt56multimedia
E: Unable to locate package qt56translations
E: Unable to locate package qt56tools
E: Unable to locate package qt56quickcontrols
greg@LinuxMacbook ~/code/librepilot $ source /opt/qt56/bin/qt56-env.sh
bash: /opt/qt56/bin/qt56-env.sh: No such file or directory

[mali]

Ok, figured it out.  (Given enough time even a monkey can figure out how to type) 

https://librepilot.atlassian.net/wiki/display/LPDOC/Linux+-+Building+and+Packaging

At some point someone who knows what they are doing (unlike me) should take a look at the docs for building and packaging Linux. The steps needed are different between LM 17.3 and LM 18. In some cases some steps are not needed and in others the order the steps are taken is different.  I suspect some difference in handling QT5.6.x. 
Also, I cane make a .deb package in LM 17.3 but not in LM 18......I'll just keep working on that