System File Checker (sfc)

Scans and verifies the versions of all protected system files after you restart your computer.

Syntax

sfc [/scannow] [/scanonce] [/scanboot] [/revert] [/purgecache] [/cachesize=x]

Parameters

/scannow : Scans all protected system files immediately.

/scanonce : Scans all protected system files once.

/scanboot : Scans all protected system files every time the computer is restarted.

/revert : Returns the scan to its default operation.

/purgecache : Purges the Windows File Protection file cache and scans all protected system files immediately.

/cachesize=x : Sets the size, in MB, of the Windows File Protection file cache.

/? : Displays help at the command prompt.

Remarks

You must be logged on as a member of the Administrators group to run sfc.

If sfc discovers that a protected file has been overwritten, it retrieves the correct version of the file from the %systemroot%\system32\dllcache folder, and then replaces the incorrect file.

If the %systemroot%\system32\dllcache folder becomes corrupt or unusable, use sfc /scannow, sfc /scanonce, or sfc /scanboot to repair the contents of the Dllcache directory.

Formatting legend

FormatMeaning

Italic

Information that the user must supply

Bold

Elements that the user must type exactly as shown

Ellipsis (...)

Parameter that can be repeated several times in a command line

Between brackets ([])

Optional items

Between braces ({}); choices separated by pipe (|). Example: {even|odd}

Set of choices from which the user must choose only one

Courier font

Code or program output

Windows File Protection

Using File Signature Verification

Driver Signing for Windows

Command-line reference A-Z



© 2014 Microsoft Corporation. All rights reserved. Contact Us |Terms of Use |Trademarks |Privacy Statement