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Determining differences between versions of text files or Web sites

Tracking changes within plain-text files themselves is difficult, since they have no provision for recording changes. Now there is a free and open source Windows application that can compare different versions of text files.

Plain-text configuration files have been a feature of Windows since its inception. Today we see more XML-format files than the classic legacy .INI file for configuring applications, but the common denominator is that they're plain-text files that can be edited "by hand" with nothing more than Notepad or an equivalent text editor.

One issue that often arises when working with text files of any kind is how things have changed from one revision of the file to another. Microsoft Word has built-in provisions for tracking changes across versions of documents, but these only work well when used with Word's native .DOC format. Tracking changes within plain-text files themselves is nigh impossible, since they have no provision for recording changes.

Enter WinMerge 2.4, a free and open-source Windows application used to compare different versions of text files, compare the changes between them, and produce change reports or merged copies of the compared files. The program can also compare multiple files in multiple directories and use wildcards to filter the comparison searches, both of which are useful capabilities for checking different editions of a Web site or a source-code tree.

Individual files can be compared side by side in a pair of windows, with changes highlighted and annotated via color bands. If you have text added or missing in one file, WinMerge non-destructively rearranges line breaks so that similar lines are always matched up side by side. The program can also read and compare files in archives without having to unpack them first (a plug-in for the popular 7-ZIP archiving tool is included), is not restricted by any maximum file size, and will work with Unicode (UTF-8) files and filenames.

Although WinMerge also works with binary files, for the best results you'll want to use an external plug-in that is currently available only with the 2.5 development version of the program. The application can also generate patch files compatible with Diffutils, a file-comparing freeware program available from GNU Software, so that the exact changes made to a given file can be reproduced separately.

Serdar Yegulalp is editor of the Windows Power Users Newsletter. Check it out for the latest advice and musings on the world of Windows network administrators -- and please share your thoughts as well!

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