One of our primary reasons for learning about non- GUI tools is to automate certain tasks. Often, however, the difficulty of automating a task isn’t finding the command-line tool that accomplishes it but rather learning a necessary scripting language such as PowerShell or VBScript. You might remember a tool called For, which I covered in this column last year (“The Power of For,” InstantDoc ID 96539). The For command essentially lets you script without scripting: It lets you apply certain commands to a series of files or folders. This month, I want to take a look at a similar tool called Forfiles, which—in some ways—is more powerful than For. (Windows Vista includes Forfiles in the box for the first time, but it's been part of the resource kit since Windows 98.)
Forfiles’ syntax is a bit ugly, but the tool is so useful that you’ll forgive its command-line unsightliness. Basically, Forfiles first searches a set of folders for files and folders that meet certain criteria, such as all .exe files in the C:\myfiles folder (and its subdirectories) that have been modified in the past 10 days. For each file or folder that Forfiles finds, the tool creates variables—with names such as @file, @ext, @path, and so on—in which it stores certain information (e.g., the file or folder’s name, its extension, its full file specification, its size, whether it’s a file or a folder, the date and time it was most recently modified). You can then use specific options to instruct Forfiles what to do with each of those files or folders.
Forfiles takes five basic options. The first, /p (for path) instructs Forfiles where to search, as in /p C:\ or /p C:\datafiles. For example, to instruct Forfiles to show you all the files in a folder named E: datafiles, you’d type
Of course, that’s a trivial use of the tool. You can use the Dir E:\datafiles command to accomplish the same task. But it does illustrate a bit of Forfiles’ syntax oddity.
What if you want to instruct Forfiles to display only files with names that start with “t”? Anyone with a small amount of experience with Windows command-line files would expect to type
But that command wouldn’t work with Forfiles because the /p option is solely for specifying a path. To use a wildcard to filter the files and folders within that path, you need to add the /m (for mask) option, along with the pattern you want Forfiles to use. (Why did the author of Forfiles choose to complicate the familiar, simple methodology of using a path with wildcards? It’s a mystery to me.)
The third option, /s ( for subdirectories), takes no parameters. As with many other Windows command-line tools, this option simply tells Forfiles to search not only inside the path but in any of that path’s subdirectories.
The /d (for date) option adds the ability to select files based on their date-modified value. You can instruct Forfiles to include only files modified exactly n days ago by adding /d -n, where n is a number between 0 and 32,767. So, to see only files from the E:\datafiles folder modified three days ago, you’d type
Alternatively, you can instruct Forfiles to display only files modified before or after a particular date. Typing /d +mm/dd/yyyy selects only files modified after that date, and typing /d –mm/dd/yyyy selects only files modified before that date. So, to display files last modified on June 1, 2006, or before, you’d type
Forfiles’ final option is /c (for command), which tells Forfiles what to do with the files and folders that it finds. If you don’t specify the /c option, Forfiles simply shows you the files that it’s collected. But the /c option lets you do so much more. I’ll cover that next time.
More than For
The For command is powerful and, in some cases, easier to use than Forfiles. However, Forfiles makes it easier to select files or folders based on several criteria, including file size and modification date. Furthermore, Forfiles makes it much easier to write commands that manipulate just part of a file’s name. Once you get past the initial learning curve, Forfiles can be a great addition to your toolkit.
Mark Minasi (www.minasi.com/gethelp) is a senior contributing editor for Windows IT Pro, an MCSE, and the author of 25 books.