This article was previously published under Q188186
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System File Checker (SFC) verifies the integrity of system files. Afterscanning for altered files, it offers to restore damaged files. If a fileis found to be damaged, SFC prompts you to restore the original file. SFCcan also be configured to notify you of changed and deleted files.
You can use SFC to:
Scan system files for damaged, missing, or changed files.
Extract original Windows 98 system files.
Track changes to the system and identify altered files.
The SFC baseline file (Default.sfc) maintains the tool's settings and aprofile of system files. The baseline contains the following informationfor each file:
Cyclical Redundancy Checksum (CRC)
The SFC baseline for the retail version of Windows 98 comes populated withWindows 98 file information. The baseline is backed up and selectivelyupdated during Windows 98 Setup. Running SFC for the first timeestablishes a profile of the system.
Default Windows 98 File Information
The following files provide the SFC baseline with the default list offiles copied by Windows 98 Setup:
The following files provide SFC with the source for the copied files:
Windows 98 Setup
Windows 98 Setup copies the Default.sfc file to Default.sf0. SFC updatesthe baseline for files such as Vmm32.vxd that have properties that canvary. SFC updates the baseline with changes to the properties for thesefiles without noting the changes in its log file (Sfclog.txt). If a fileis missing, it is removed from the baseline.
The Sfcsync.txt file is a list of files to silently update in the SFCbaseline during Setup. Sfcsync.txt is limited to the following locations:
Sfcsync.txt Actual location ------------------------------------- 10 Windows 11 Windows\System 12 Windows\System\Iosubsys 13 Windows\Command 22 Windows\System\Vmm32
Create System Profile
The first time SFC runs, it creates a profile of the system. All of thechanges to the baseline are noted in the Sfclog.txt log file, with theexception of missing files.
Missing files are silently removed from the baseline the first time SFCruns, even if you enable notification for missing files. Files that areremoved after SFC runs for the first time are identified as missing thenext time SFC runs. You are prompted to restore the file if SFC isconfigured to check for missing files.
Changed files are noted in the log file and you are notified if thesetting is enabled. A file is identified as changed if its date andversion information changes. Changed files are identified in theSfclog.txt file as "Updated" unless you enabled notification for changedfiles and chose to restore the original file.
You are always notified of damaged files. A file is identified as damagedif its date and version match, but the CRC value does not match thebaseline.
You are not notified of files that are added to the baseline. Filesthat are added to the baseline are noted in the log file as "Added."