colours in the shell!

lib/shell.lua

@@ -22,17 +22,18 @@ function shell.interactive()
  local shenv = setmetatable({}, {__index=shindex})
  local run = true
  while run do
-  io.write(string.format("%s:%s> ",os.getenv("HOSTNAME") or "localhost",(os.getenv("PWD") or _VERSION)))
+  io.write(string.format("\27[32m%s:%s>\27[0m ",os.getenv("HOSTNAME") or "localhost",(os.getenv("PWD") or _VERSION)))
   local input = io.read()
   if input:sub(1,1) == "=" then
    input = "return "..input:sub(2)
   end
   local f, r = load(input, "shell", "t", shenv)
   if not f then
-   print(r)
+   print("\27[31m"..r)
   else
    local rt = {pcall(f)}
    local rs = table.remove(rt,1)
+   if not rs then io.write("\27[31m") end
    for k,v in pairs(rt) do
     print(formatValue(v))
    end

module/vt100.lua

@@ -31,6 +31,8 @@ function vt100emu(gpu) -- takes GPU component proxy *gpu* and returns a function
      cx = 1
     elseif cc == "\27" then -- escape
      mode = "e"
+    elseif cc == "\t" then
+     cx = 8*((cx+9)//8)
     elseif string.byte(cc) > 31 and string.byte(cc) < 127 then -- printable, I guess
      gpu.set(cx, cy, cc)
      cx = cx + 1