Simple, conventional argument parsing with a friendly license. For Lua 5.1 and later. See the source file header for full documentation.
getopt = require('getopt') local append = false local binary = false local color = 'white' local nonoptions = {} local infile = io.input() for opt, arg in getopt(arg, 'abc:h', nonoptions) do if opt == 'a' then append = true elseif opt == 'b' then binary = true elseif opt == 'c' then color = arg elseif opt == 'h' then usage() os.exit(0) elseif opt == '?' then print('error: unknown option: ' .. arg) os.exit(1) elseif opt == ':' then print('error: missing argument: ' .. arg) os.exit(1) end end if #nonoptions == 1 then infile = io.open(nonoptions[1], 'r') elseif #nonoptions > 1 then print('error: wrong number of arguments: ' .. #nonoptions) os.exit(1) end -- ...$ lua tests.lua