How do install libraries for both Lua5.2 and 5.1 using Luarocks?

As suggested by moteus, I decided to install a second version of Luarocks for Lua 5.1. But he is using Windows and I am using Linux so here is what I did:

• Download the source for the latest version of Luarocks on the Luarocks website

• From the source directory, run the ./configure script:

  /configure --prefix="${HOME}/.luarocks51" --lua-suffix=5.1

  The prefix setting tells Luarocks to put its stuff on the .luarocks51 folder, next to the existing .luarocks folder from my 5.2 install of Luarocks. The lua-suffix parameter tells Luarocks to use Lua 5.1 instead of the default lua version in my machine (5.2). This depends on me having named the interpreter for Lua 5.1 as lua5.1 (Debian installed mine on /usr/bin/lua5.1). Finally, Luarocks managed to automatically detect where the 5.1 headers and libraries are installed (/usr/include/lua5.1/) but if it didn't I guess I could have specified that with the --with-lua-include and --with-lua-lib parameters.

• Compile Luarocks with make

• Install it with make isntall (no need for Sudo since I'm installing it in a local directory).

• Configure my 5.1 environment to use the libraries downloaded by Luarocks. I added the following to my .bashrc:

  export PATH=$PATH:~/.luarocks/bin:~/.luarocks51/bin
  export LUA_CPATH=";;${HOME}/.luarocks51/lib/lua/5.1/?.so"
  export LUA_PATH=";;${HOME}/.luarocks51/share/lua/5.1/?.lua;${HOME}/.luarocks51/share/lua/5.1/?/init.lua"
  
  export LUA_CPATH_5_2=";;${HOME}/.luarocks/lib/lua/5.2/?.so"
  export LUA_PATH_5_2=";;${HOME}/.luarocks/share/lua/5.2/?.lua;${HOME}/.luarocks/share/lua/5.2/?/init.lua"
  

  The 5.1 configuration also works for Luajit.

• The executable for the 5.1 version of luarocks is named luarocks-5.1:

  luarocks-5.1 install lfs
  

Based on your reference to ~/.luarocks/share/lua/5.2/, you seem to be running a Unix system (Linux or Mac). You can install the latest version of LuaRocks twice, for both Lua 5.1 and Lua 5.2 like this:

./configure --lua-version=5.1 --versioned-rocks-dir
make build
sudo make install

And then again for 5.2:

./configure --lua-version=5.2 --versioned-rocks-dir
make build
sudo make install

This will get you /usr/local/bin/luarocks-5.1 and /usr/local/bin/luarocks-5.2. If you installed Lua 5.1 and 5.2 in /usr/local/, and each of them will use its own ~/.luarocks/lib/luarocks/rocks-5.x/ entry for the user tree (and /usr/local/lib/luarocks/rocks-5.x for the system tree), and install modules to the right location at /usr/share/lua/5.x/ and ~/.luarocks/share/lua/5.x/ (and likewise for lib) appropriately.