Since we escape $PATH, we can't just try to export that way. Since PATH
is unset if we do this, we end up with things like :
./Tools/scripts/install-prereqs-ubuntu.sh: line 101: apt-cache: command
not found
If we are running the script, we are likely inside the repository, in
which case the script would fail while searching for a directory named
ardupilot. Derive the root directory from the script location.
ubuntu@ubuntu-xenial:~/ardupilot$ ./Tools/scripts/install-prereqs-ubuntu.sh
./Tools/scripts/install-prereqs-ubuntu.sh: line 19: python-wxgtk3.0: command not found
While at each, change to use lsb_release like the other scripts.
The realpath tool may be missing on a Ubuntu distro and we use it in
sim_vehicle.sh. Make sure it's also installed as part of sitl packages.
On Archlinux it's part of the coreutils package which is part of the
base group. Therefore it's guaranteed to be available.
Fix#2730.
Updated the README and the install-prereqs-ubuntu.sh script to reflect
changes in the PX4 build steps and the PX$ & NuttX repository used to
build ardupilot.
development environment.
Added a script, install-prereqs-ubuntu.sh, that installs all packages
and software required for development on AVR and PX4 platforms.
pch: rebased pullreq 183
