Using MpCmdRun.exe to Update Windows Defender and Run a Quick Scan in One Go

The Windows Defender command-line utility MpCmdRun.exe is prominently used for scheduling scans and updating the signature or definition files. The MpCmdRun.exe command usage info can be obtained by running MpCmdRun.exe with "/?" or without any parameter. However it doesn’t mention a useful switch that updates Windows Defender signatures and runs a Quick Scan at once. And this switch is not documented anywhere thus far.

Generally, if a feature or hidden "switch" in a software is not documented officially, there is a chance that the manufacturer may have missed updating the help files. However if you’re someone who doesn’t take anything for granted, you could test such hidden feature in a test computer, just in case. I’ve used and tested the undocumented SignatureUpdateAndQuickScan in my production computer, and the switch worked exactly as intended without any problems.

Signature Update & Quick Scan – Hidden Switch

To update the definitions and run a Quick Scan in one go, use the switch SignatureUpdateAndQuickScan (MpCmdRun.exe /SignatureUpdateAndQuickScan).

… and the event written to Microsoft-Windows-Windows Defender/Operational log.

This switch works in Windows 10 as well as in Windows 8 systems.

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About the author

Ramesh Srinivasan founded back in 2005. He is passionate about Microsoft technologies and he has been a Microsoft Most Valuable Professional (MVP) for 10 consecutive years from 2003 to 2012.

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