lesspipe

Lesspipe is a Unix utility that provides a mechanism for filtering input through a specified program before it is displayed by the pager less. This allows for pre-processing of text or data before it is viewed interactively. The primary function of lesspipe is to enable less to handle file types that it would not otherwise be able to display directly, such as compressed archives, formatted documents, or specialized data formats.

When less is invoked with a file that lesspipe is configured to handle, lesspipe intercepts the file. It then executes a user-defined command or script associated with that file type. The output of this command is then piped as standard input to less. This means that users can, for instance, view the contents of a gzipped tar archive as if it were a plain text file, or see the rendered content of a Markdown document without needing to convert it manually first.

Configuration of lesspipe typically involves setting up a configuration file, often located in the user's home directory or system-wide. This file maps file extensions or MIME types to specific commands. When less encounters a file matching an entry in the configuration, it executes the corresponding command. This makes less a more versatile tool for exploring diverse file types directly from the command line.