What is the Sfc Command?
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] [/offbootdir=boot] [/offwindir=win] [/?]
/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.
/offbootdir=boot = Used with /offwindir, this sfc option is used to define the boot directory (boot) when using sfc from outside of Windows.
/offwindir=win = This sfc option is used with /offbootdir to define the Windows directory (win) when using sfc offline.
/? = 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
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.
Here, the sfc command is used to scan ieframe.dll and then repair it if an issue is found.
sfc /scannow /offbootdir=c:\ /offwindir=c:\windows
In this example, protected Windows files are scanned and repaired if necessary (/scannow) but this is done so with a different installation of Windows (/offwindir=c:\windows) on a different drive (/offbootdir=c:\).
Tip: The above example is how you would use the sfc command from the Command Prompt in System Recovery Options or from a different installation of Windows on the same computer.
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: Depending on how your computer was setup, you may need access to your original Windows installation disc or flash drive to allow file repairs.
Sfc Command Availability
System File Checker is part of Windows Resource Protection in Windows 8, 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.
Important: The sfc command can only be run from the Command Prompt when opened as an administrator. See How To Open an Elevated Command Prompt for information on doing that.
Note: The availability of sfc command switches may differ somewhat from operating system to operating system.
Sfc Related Commands
The sfc command is often used with many other Command Prompt commands.
Many troubleshooting steps advise the use of the sfc command.