What is the Sfc Command?

The sfc command is a Command Prompt command that can be used to verify and replace important Windows system files.
System File Checker is a very useful tool to use when you suspect issues with protected Windows files like many DLL files.

Sfc Command Syntax:

sfc [/scannow] [/verifyonly] [/scanfile=file] [/verifyfile=file] [/offwindir=win] [/offbootdir=boot] [/?]
Tip: See How To Read Command Syntax if you’re not sure how to interpret the sfc command syntax above.
/scannow = This option instructs sfc to scan all protected operating system files and repair as necessary.
/verifyonly = This sfc command option is the same as /scannow but without repairing.
/scanfile=file = This sfc option is the same as /scannow but the scan and repair is only for the specified file.
/offwindir=win = Used with other sfc options to define the Windows directory (win) when using sfc offline.
/offbootdir=boot = Similar to /offwindir, this sfc option is used to define the boot directory (boot).
[/?] = Use the help switch with the sfc command to show detailed help about the command’s several options.
Tip: You can save the output of the sfc command to a file using a redirection operator. See How To Redirect Command Output to a File for instructions or check out Command Prompt Tricks for more tips like this.

Sfc Command Examples:

sfc /scannow

In the above example, the System File Checker utility is used to scan and then automatically replace any corrupt or missing system files. The /scannow option is the most commonly used switch for the sfc command.
See How To Use SFC /Scannow to Repair Protected Windows Operating System Files for more information on using the sfc command in this way.

sfc /scanfile=c:windowssystem32ieframe.dll

Here, the sfc command is used to scan ieframe.dll and then repair it if an issue is found.

sfc /verifyonly

Using the sfc command with the /verifyonly option, System File Checker will scan all protected files and report any issues but no changes are made.
Important: You may need access to your original Windows DVD or CD to allow file repairs.

Sfc Command Availability:

The sfc command is available from within the Command Prompt in most Windows operating systems including Windows 7, Windows Vista, Windows XP, and Windows 2000.
System File Checker is part of Windows Resource Protection in Windows 7 and Windows Vista and is sometimes referred to as Windows Resource Checker in those operating systems.
System File Checker is part of Windows File Protection in Windows XP and Windows 2000.

Note: The availability of sfc command switches may differ somewhat from operating system to operating system.