\"xp_cmdshell\" is a malicious code term commonly used in cyber attacks to inject malicious code into a system, usually to gain unauthorized access. It is not a杀毒软件, but a term used in the context of computer security to refer to a specific type of attack, where a malicious userscript is executed by the attacker using the \"cmdshell\" environment, which is a part of the Windows operating system.
In order to install or use a杀毒软件, you should follow the steps provided by the vendor or the official website of your computer operating system. Additionally, it is important to have a strong understanding of computer security principles and to regularly update your software and operating system to ensure your system is highly secure.