Installing lua5.2 vs. lua5.3 on Ubuntu 16.10

Question

When I install the lua5.2 package on Ubuntu 16.10:

sudo apt-get install lua5.2

it installs /usr/bin/lua as a symlink to /etc/alternatives/lua-interpreter, which in turn is a symlink to `/usr/bin/lua5.2.

When I install the lua-5.3 package, it doesn't create the symlinks; I only get /usr/bin/lua5.3.

The output of dkg -L lua5.X, which lists the files owned by the package, is identical (aside from version numbers on some files) for the lua5.2 and lua5.3 packages.

What I want to do is just install the latest and greatest version of Lua, which is currently 5.3, and be able to use #!/usr/bin/lua in scripts.

I know I can work around this by creating the symlinks manually or by using the update-alternatives command (which I haven't yet figured out, but that's not what I'm asking about).

My question is, why does the lua5.3 package not set up the /usr/bin/lua symlink when I install it, while the lua5.2 package does? Is this deliberate, perhaps an Ubuntu policy, or is it just an oversight by the people who created the package?

Answer 1

This is still an issue in 18.04 Bionic. Workaround:

sudo update-alternatives --install /usr/bin/lua lua-interpreter \
/usr/bin/lua5.3 130 --slave /usr/share/man/man1/lua.1.gz \
lua-manual /usr/share/man/man1/lua5.3.1.gz

sudo update-alternatives --install /usr/bin/luac lua-compiler \
/usr/bin/luac5.3 130 --slave /usr/share/man/man1/luac.1.gz \
lua-compiler-manual /usr/share/man/man1/luac5.3.1.gz

Answer 2

Because the package maintainer didn't provide the alternatives infrastructure. Unfortunately no way around it but to set it up manually or just plain symlink /usr/bin/lua to /usr/bin/lua5.3.

I've submitted a bug report: https://bugs.launchpad.net/ubuntu/+source/lua5.3/+bug/1707212