start a cmd.exe windows with another TeX distro activated

distsel.lua

-- distsel.lua: start a cmd.exe windows with another TeX distro activated
-- Manuel Pégourié-Gonnard, 2010. WTFPL v2.

local usage = [[texlua c:\path\to\distsel.lua DistName C:\path\to\distro]]

-- arguments
if not arg[2] then
    io.stderr:write('Usage: ' .. usage)
    os.exit(1)
end
local new_distro_name = arg[1]
-- for some reason, path arguments get their \ turned to /, undo that
local new_distro_path = arg[2]:gsub('/', '\\')

-- get our own location
kpse.set_program_name(arg[-1])
local my_dir = kpse.var_value('SELFAUTOLOC')

-- normalize a path for comparison
local function normalize_path(name)
    return name:lower():gsub('/', '\\')
end
local current_distro = normalize_path(my_dir)

-- compute new path
local new_path_dirs = {}
local old_path = os.getenv('PATH')
for _, dir in ipairs(old_path:explode(';')) do
    local newdir = dir
    if normalize_path(dir) == current_distro then
        newdir = new_distro_path
    end
    table.insert(new_path_dirs, newdir)
end
local new_path = table.concat(new_path_dirs, ';')

-- set the new path and open a cmd.exe window
os.setenv('PATH', new_path)
os.execute('start "'..new_distro_name..'" cmd.exe')

gistfile2.txt