The Road to KDE 4: Strigi and File Information Extraction

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After a short delay due to a heavy dosage of Real Life(tm), I return to bring you more on the technologies behind KDE 4. This week I am featuring Strigi, an information extraction subsystem that is being fully deployed for KDE 4.0. KDE has previously had the ability to extract information about files of various types, and has used them in a variety of functional contexts, such as the Properties Dialog. Strigi promises many improvements over the existing versions. Read on for more...

Strigi is a library that sits at a lower level than KDE. It is written in C++, and is designed to present a series of generic calls that a program can use to find more information about a given file or files. It is in no way tied to KDE except that the development version lives in KDE's SVN repository. It also has search capabilities, which are not really the focus of this article.

The Strigi libraries are used to get information from within files, such as the dimensions of an image, or the length of an audio clip, embedded thumbnails, number of lines in a log, source code licensing info or just to search a text file for a given string. Strigi has other advantages, as it can work inside compressed files, archives, and so forth seamlessly. In fact, it ships a few useful utility programs, called deepgrep and deepfind. These useful command line programs allow you to search for information within binary file formats as easily as using grep or find on plain text files. KDE is inheriting the same libraries, so we also get this unique advantage of being able to pull information out of files that are buried within binary formats, such as .tgz files.

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