View difference between Paste ID: nf3ZrxYV and CYQp63kb

 local args = {...}
 
 if not args[1] then
 	print("Usage:")
 	print(shell.getRunningProgram() .. " <program> [program arguments, ...]")
 	return
 end
 
 local path = shell.resolveProgram(args[1]) or shell.resolve(args[1])
 
 -- here be dragons
 local function buildStackTrace(rootErr)
 	local trace = {}
 	local i, hitEnd, _, e = 4, false
 
 	repeat
 		_, e = pcall(function() error("<tracemarker>", i) end)
 		i = i + 1
 		if e == "xpcall: <tracemarker>" or e == "pcall: <tracemarker>" then
 			hitEnd = true
 			break
 		end
 		table.insert(trace, e)
 	until i > 10
 
 	table.remove(trace)
 	table.remove(trace, 1)
 
 	if rootErr:match("^" .. trace[1]:match("^(.-:%d+)")) then table.remove(trace, 1) end
 
 	local out = {}
 
 	table.insert(out, rootErr)
 
 	for i, v in ipairs(trace) do
 		table.insert(out, "  at " .. v:match("^(.-:%d+)"))
 	end
 
 	if not hitEnd then
 		table.insert(out, "  ...")
 	end
 
 	return table.concat(out, "\n")
 end
 
 if fs.exists(path) then
 	local eshell = setmetatable({getRunningProgram=function() return path end}, {__index = shell})
 	local env = setmetatable({shell=eshell}, {__index=_ENV})
 
 	env.pcall = function(f, ...)
 		local args = { ... }
 		return xpcall(function() f(unpack(args)) end, buildStackTrace)
 	end
 
 	env.xpcall = function(f, e)
 		return xpcall(function() f() end, function(err) e(buildStackTrace(err)) end)
 	end
 
 	local f = fs.open(path, "r")
 	local d = f.readAll()
 	f.close()
 
 	local func, e = load(d, fs.getName(path), nil, env)
 	if not func then
 		printError("Syntax error:")
 		printError("  " .. e)
 	else
 		table.remove(args, 1)
 		xpcall(function() func(unpack(args)) end, function(err)
 			local stack = buildStackTrace(err)
 			printError("\nProgram has crashed! Stack trace:")
 			printError(stack)
 		end)
 	end
 else
 	printError("program not found")
 end