Simple answer: "C:\program files\windows defender\mpcmdrun.exe" -scan -scantype 2
Elaborated:
1) Open a simple (not elevated) command prompt.
It should not be necessary to open an elevated one.
2) Type/copy--> "C:\program files\windows defender\mpcmdrun.exe" -scan -scantype 2
C:\program files\windows defender\mpcmdrun.exe should be the deafult location of mpcmdrun.exe
Using only -scan parameter will use the default settings of Windows defender/essentials
To be certain that it will be performed a full system scan, you need to use the -scantype 2 parameter, like said in the mpcmdrun help.
3) If you have errors, first try to locate where it is the mpcmdrun.exe file on your machine.
This is usually and easily done with a simple search:
From command prompt: dir /a /b /s c:\mpcmdrun.exe
From the run window, shortcut: Windows key + R key (Windows + R), or from Windows vista/7 searchbox (right over the start button, after you have clicked it), or from Windows 8/8.1 charm search, or from Windows 8/8.1 - right-click on the start button - run:
cmd /k dir /a /b /s c:\mpcmdrun.exe
Extracted from the mpcmdrun help:
-Scan [-ScanType #] [-File <path> [-DisableRemediation]] Scans for malicious software
-Scan [-ScanType value]
0 Default, according to your configuration
1 Quick scan
2 Full system scan
3 File and directory custom scan
[-File <path>]
Indicates the file or directory to be scanned, only valid for custom scan.
2The screenshot on that page and
MpCmdRun /?
clearly state -Scan [-ScanType] (see the - before ScanType?) – Karan – 2012-10-01T22:05:11.547