I happened to chance upon Rename file extensions in bulk from command line [CMD] in which the author contributed the script below: Code: forfiles /S /M *.ext1 /C "cmd /c rename @file @fname.ext2" He did not provide much explanation and that is why I post my questions here. They are: 1. What are the functions of the switches /S /M ? 2. There is a /C in the command. Does it mean the whole of C:\ drive? 3. What does /c do? My objective is very simple. In C:\Windows\System32\DriverStore\FileRepository there is a folder called abcde12345 with at least 5 sub-folders. After taking ownership of abcde12345 folder, I wish to rename in bulk in the sub-directories all the files of extensions cat, dll, exe, inf, pnf, sys to .cat.bak .dll.bak .exe.bak, .inf.bak, .pnf.bak, .sys.bak I will cd to \Windows\System32\DriverStore\FileRepository\abcde12345 and run my customized script (see below). Please correct it if it is wrong: Code: forfiles /S /M *.* "cmd /c rename @file @fname.*.bak" I appreciate your help in this.