steamCMD安装：https://www.jianshu.com/p/3c9950a7ff86
服务器搭建：https://cloud.tencent.com/developer/article/1186455
https://blog.csdn.net/qq741058114/article/details/81287465
指令大全：https://wenku.baidu.com/view/a60040be443610661ed9ad51f01dc281e53a56e3.html
login anonymous
force_install_dir ./L4D2-server
app_update 222860 validate