开启xp_cmdshell：

exec sp_configure 'show advanced options', 1;
reconfigure;
exec sp_configure 'xp_cmdshell', 1;
reconfigure;
exec sp_configure 'show advanced options', 0;
reconfigure;

关闭xp_cmdshell：

exec sp_configure 'show advanced options', 1;
reconfigure;
exec sp_configure 'xp_cmdshell', 0;
reconfigure;
exec sp_configure 'show advanced options', 0;
reconfigure;