"./?.lua;./?.lc;/usr/local/?/init.lua"
the search for the name foo.a will try to open the files ./foo/a.lua, ./foo/a.lc, and /usr/local/foo/a/init.lua, in that order.
The package path is also initialized from the environment variable LUA_PATH,
package.path
The path used by require to search for a Lua loader.
At start-up, Lua initializes this variable with the value of the environment variable LUA_PATH_5_3 or the environment variable LUA_PATH
From the lua manual
The package path is also initialized from the environment variable LUA_PATH,