@Thomas (Tvk7) it looks like you are using lua 5.2, where as Alex G's symlink solution is for lua 5.1.
The relevant symlink for 5.2 would be: sudo ln -s /usr/lib/x86_64-linux-gnu/lua/5.2/posix_c.so /usr/lib/x86_64-linux-gnu/lua/5.2/posix.so
@Thomas (Tvk7) it looks like you are using lua 5.2, where as Alex G's symlink solution is for lua 5.1.
The relevant symlink for 5.2 would be: x86_64- linux-gnu/ lua/5.2/ posix_c. so /usr/lib/ x86_64- linux-gnu/ lua/5.2/ posix.so
sudo ln -s /usr/lib/