Auto Update (startup)

pastebin=""
backup=""
file=""

print("[ Updating script to latest version ]")
if (fs.exists(backup)) then
    print("Old backup file detected, deleting: " .. backup)
    fs.delete(backup)
end
if (fs.exists(file)) then
    print("Creating new backup file: " .. backup)
    fs.move(file, backup)
end
print("Fetching latest (" .. file .. ") version from pastebin: " .. pastebin)
result = shell.run("pastebin", "get " .. pastebin .. " " .. file)
print("Operation finished. Result: ")
if (result) then print("Success")
else print("Failure")
end
print("Attempting to run: " .. file)
if (not fs.exists(file)) then
    print("Error: File not found: " .. file)
    print("Attempting reverting to backup...")
    if (not fs.exists(backup)) then
        print("Fatal error: No backup file found.")
        error("Stopping...")
    end
    fs.copy(backup, file)
end
print("Executing: " .. file)
shell.run(file)