File tagging is a way of organizing files or folder by applying tags to them. This tag can then be used to search for data, and sort the files accordingly. With this feature, you can tag files into categories irrespective of their location. This gives you a new way to organize your files.
First, select the file/folder to which you want to add tags and then press Add on the information panel. Now, you can either create a new tag or add an existing tag to the respective file/folder, as shown in the above screenshot. Press Save once you are done.
Search and tags in KDE4
On the All tags page, you can right-click and copy a particular tag and paste it to a location you like. This will paste all the entries with that particular tag into a separate folder.
KDE (K Desktop Environment) is aFree Software environment for desktops and portable computers that has been created by an international technology team. Among KDE's products are a modern desktop system (window manager, file manager, desktop search), comprehensive office productivity and groupware suites, and hundreds of applications for Internet and web, multimedia, entertainment, education, graphics, and software development. KDE software is translated into more than 60 languages and is built with ease of use and modern accessibility principles in mind.
KDE version 4.0 is a significant release that has been available since January 11, 2008. The libraries, desktop, applications, and artwork have been improved and adapted, and it now runs natively on a wider set of operating systems that include Linux, BSD, Solaris, Windows and Mac OS X. As part of this release, the search engine was overhauled and desktop annotation introduced. Based on standards and technologies developed in the NEPOMUK Semantic Desktop project, the search engine is now based on RDF and allows users to annotate and search for their files using Semantic Web standards.
It was decided for KDE4 that a capable desktop search engine was needed with functionality for fast full text search, and semantic search for enhanced retrieval accuracy. Support for tagging and annotations of files was also requested by many users. As KDE is a platform, it was important that the search and annotation services were made available across all applications, allowing users to annotate and find documents independent of the program or file format.
For the new KDE version 4.0, the NEPOMUK EU projectcontributed a semantic search and annotation engine calledSoprano, based on RDF. The desktop search service provides an integrated search on all information the user has stored on their computer. This allows users to search for e-mails, appointments, contacts, and files using a single interface. The NEPOMUK project was able to provide such facilities by exploiting metadata in powerful ways. The core elements of NEPOMUK have already been integrated into KDE.
Using RDF, Soprano allows developers to index and search documents independent of application format, file format, or other implementation requirements. Given that thousands of new file and application formats may be added by the various applications that KDE supports, the extensibility of RDF was considered a key feature.
This capability is provided through the use of Semantic Web standards. RDF is used as the mechanism for assigning tags to files because it is powerful and extensible. RDF Schema (RDFS) is used to create a simple ontology that is used for normalizing the tag terms, so that all files of interest can be retrieved.
Future development plans include embedding search functions into more KDE applications, thereby providing powerful query capabilities regardless of the application that is being used. A particularly interesting use case is allowing users to perform arbitrarily complex semantic queries to retrieve emails through a selection of virtual folders in KMail. For example, toshow mails from people who I have met in meetings in the last week.
Figure 2: The KDE File Analyzer can be used to index metadata, thus enabling users to perform queries across file metadata, and tags and rating systems (a larger version of the image is also available).
The implementation of the search capability within KDE 4.0 was based on RDF and RDFS. The key features of interest with these technologies included the extensible and adaptive data model, and fast storage and retrieval of data.
Applications such as Dolphin store tags and ratings in xattrs (extended attributes) in the filesystem, and Baloo indexes these so you can search them.On Linux, to show them as entered in Dolphin, in a terminal enter:
Most CLI utilities (e.g. cp, tar, rsync) won't copy xattrs without additional flags either, so unless your environment is 'All KDE all the time' and you only use Linux filesystems like ext4, XFS, or Btrfs (this is not a complete list), and you modify your backups to specifically include xattrs, your tags may get trashed one way or another.
Nepomuk (the previous KDE tagging/file metadata system) was used to store tags in a separate database, but even after many years of development, it could hardly be made to work performantly or reliably so it was replaced with Baloo.
In some ways using xattrs is 'the right place' to put this tagging info, but Linux doesn't have a 'core API' that would allow a 'xattrs preserved by default, and interpreted consistently' policy. Therefore there are a lot of ways to lose your tags. KDE has been trying to make this work for many years, but it is difficult given the way UNIX/POSIX has evolved.
The search is case insensitive, and does not require surrounding wildcards (*foo* and foo are equivalent), but you can use wildcards inside the search term. * will match zero or more characters, ? only one single character.
From KDE Applications 4.13 onwards, the 'Baloo' file indexing and file search framework replaces Nepomuk. Read details on the changes for Applications 4.13 here. Semantic Search no longer uses a single, big database, but separate, specialized databases for each type of data. The new search databases are in $HOME/.local/share/baloo. If you upgraded to KDE Applications 4.13 from an earlier KDE release, you can delete $KDEHOME/share/apps/nepomuk.
For example, the Dolphin file manager makes use of Search. In KDE Applications versions prior to 4.13 Semantic Search must be enabled from System settings -> Desktop search. The information sidebar of Dolphin (Control -> Panels -> Information, or press F11) presents information extracted by Search about the selected file, and also allows you to assign tags, ratings and comments to files. This information is then stored and indexed by Search. You can then search for metadata using the navigation bar in Dolphin. Click to Find, or press Ctrl+F, and search for file names or file contents.
The third layer is a very complex one, and the reason why the underlying technology, Nepomuk, was conceived as a research project of several companies and universities in the European union. This is where you will find difficult words like 'semantic desktop' and 'ontologies'. Basically, it is about context and relationships.
All in all, this part of Semantic Search is about making search smart. Think about how Google tries to be smart with your searches: when you search for a hotel and a city name, it shows above the website results a google map showing hotels in the city you mentioned! It might even suggest a better name in case you made a spelling mistake. Google also tries to put the most relevant information on top of the list of results, using complex calculations on relationships (links) between websites. Semantic Search will be able to offer such smart results and order them on relevancy using relationship information.
These relationships can not only help you while searching for files, but also have an influence on applications and what information they present. Note that this way of using Search is still more a vision than reality! Many of the components are in place, but it is not yet integrated in applications and the desktop as a whole.
In versions of the KDE Applications before 4.13, Semantic Search would have components running separate from applications. This functionality could be disabled by unchecking Enable Nepomuk File Indexer in the Desktop Search section of System Settings. In case you want to turn off all semantic features, uncheck Enable Nepomuk Semantic Desktop. Notice that this will turn off search in Dolphin as well.
There is one thing I need to touch on before pointing to other sources of information: sharing Nepomuk data. It'd be great if your tags, ratings and comments would be shared with others when you send them files. However, if you tagged a contact with a slightly embarrassing tag ('boring in bed') and send that persons contact information to a mutual friend you probably don't want that tag to be send as well...
This issue is of course being considered and an important subject of research by the Nepomuk researchers. For the time being, these privacy concerns, combined with technical challenges, are the reason Nepomuk context is private. Rest assured the Nepomuk team does all it can to make sure your privacy is respected.
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