To suppress the creation of a log file during a command line operation, use SPFServerManager.exe and the /nolog parameter with a value of True. This argument will suppress the output of any log file, for Server Manager or other services, although errors are still logged.
For example, the commands shown below will each execute without generating a log file:
SPFServerManager.exe /showsitesettings /nolog:True
SPFServerManager.exe /siteinfo /sn:[Valid site name] /nolog:True