Add support for newer Lua versions

[mimi89999]

Hello,
Currently raspi-config depends on lua5.1 (https://github.com/RPi-Distro/raspi-config/blob/bookworm/debian/control#L12). Would it be possible to add support for newer versions of Lua and not depend on that very old Lua?

[XECDesign]

I haven't used lua in many many years, so I don't know if we can just switch over to 5.4 without any changes to the snippets of lua in raspi-config itself. It doesn't look like there's anything tricky going on and 5.4 should just work, but I don't have time to check that right now.

local key=assert(arg[1])
local fn=assert(arg[2])
local file=assert(io.open(fn))
for line in file:lines() do
  if line:match("^%s*"..key.."=.*$") then
    line="#"..line
  end
  print(line)
end

local key=assert(arg[1])
local fn=assert(arg[2])
local file=assert(io.open(fn))
local found=false
for line in file:lines() do
  local val = line:match("^%s*"..key.."=(.*)$")
  if (val ~= nil) then
    print(val)
    found=true
    break
  end
end
if not found then
   print(0)
end

It looks like these could just be rewritten to use sed and the lua dependency could be dropped entirely.

[mimi89999]

I tested the code with Lua3.4 and it seems to be working fine. I fear that switching to sed might potentially introduce new bugs and make the code less readable.

[mimi89999]

Anyway, the lua command is called and it's handled by the Debian alternatives system:

michel@kokomi:~ $ which lua
/usr/bin/lua
michel@kokomi:~ $ ls -l /usr/bin/lua
lrwxrwxrwx 1 root root 33 Feb 21  2023 /usr/bin/lua -> /etc/alternatives/lua-interpreter
michel@kokomi:~ $ ls -l /etc/alternatives/lua-interpreter
lrwxrwxrwx 1 root root 15 Aug 28 21:09 /etc/alternatives/lua-interpreter -> /usr/bin/lua5.4
michel@kokomi:~ $ sudo update-alternatives --list lua-interpreter
/usr/bin/lua5.1
/usr/bin/lua5.4

So even though the package depends on lua5.1, the lua command could be any version of lua 🤷‍♂️

[XECDesign]

Thanks for checking and that's a good point about the lua symlink. But I still think the lua snippets are a bit out of place in a shell script. I don't think it will be any less readable. It would be using the same regular expressions, which is usually the least readable part.