yelp

yelp [OPTION...] [URI...]

-h, --help
    Shows general help options and exits.

--help-all
    Shows all help options, including less common or debugging ones.

--help-gst
    Shows GStreamer-specific options, typically used for multimedia documentation.

--display=DISPLAY
    Specifies the X display to use for the graphical interface, useful in multi-display or remote X setups.

-s, --search=TEXT
    Initiates a search for the specified TEXT within the loaded or default documentation.

-u, --uri=URI
    Loads the specified Uniform Resource Identifier (URI). This option is officially deprecated but still functional. It is recommended to pass URIs directly as arguments without the -u flag for newer usage.

--version
    Displays the version information of yelp and exits.

--debug
    Enables debug mode, providing more verbose output to the console for troubleshooting and development purposes.

URI...
    One or more URIs to open. yelp supports various URI schemes like help: for local documentation (e.g., help:yelp/index or help:gnome-terminal/index) or standard web schemes like HTTP/HTTPS for online resources.

yelp is the default help browser for the GNOME desktop environment, designed to display documentation in various formats, primarily Mallard (the official GNOME help format) and DocBook. Users can access help files for applications, system components, and general desktop usage through yelp. It provides a graphical interface for browsing, searching, and navigating help topics, often accessible via an application's "Help" menu or by directly invoking the yelp command with a URI. Its purpose is to provide an accessible and integrated help system for GNOME users, allowing for easy access to application-specific and general system help.

yelp is primarily designed for and integrated with the GNOME desktop environment. Its optimal functionality and primary support are for documentation written in Mallard and DocBook formats. While it can open other document types, its core strength lies in these structured help formats. The -u or --uri option is considered deprecated; passing URIs directly as arguments is the preferred method.

yelp extensively uses URIs to locate and display documentation. For local help, the help: scheme is common, e.g., help:gnome-terminal/index to open the help for GNOME Terminal, or help:yelp/index for yelp's own help. These URIs often point to specific topics or the main index of an application's documentation. Users can also specify direct file paths (e.g., file:///path/to/doc.xml) or web URLs (e.g., https://developer.gnome.org/) for external resources.

The primary documentation formats natively supported and optimized by yelp are Mallard and DocBook XML. Mallard is the recommended GNOME help format, known for its topic-oriented approach and re-usability, making it ideal for software documentation. DocBook XML is a widely adopted standard for technical documentation, offering robust structuring capabilities. While these are its core strengths, yelp can also render basic HTML content and plain text files, and in some configurations, it might integrate with other viewers like evince to open PDF documents.

yelp has served as the official help browser for the GNOME desktop environment since its early versions. It was developed to provide an integrated, user-friendly system for accessing application and system documentation, aiming to replace more disparate help solutions. Over time, its development has closely tracked the GNOME project's evolution, with a significant shift towards supporting modern web technologies for rendering and indexing help content. This led to the adoption of the Mallard format as its primary documentation standard, designed for topic-oriented and re-usable content, aligning with broader GNOME documentation efforts.

man(1), info(1), evince(1)