"Library for creating command line applications" - A kernel to build CLI applications from Horde libraries.
Horde_Argv is used to define parsers for commandline arguments given to a program. It bisects a command line into positional arguments and options: shorthand (-h) or long form (--help), flags or typed values (--format=xml) and supports printing out usage help or validating commandlines against value constraints.
Horde_Cli provides utilities for input and output on a text terminal command line, using text colors and background colors where available or falling back to simple text, wrapping to screen width etc.
Horde_Cli_Modular provides tools to bundle commandline parsing and input/output into reusable, pluggable modules that each represent one command with appropriate switches and may have sub commands.
Integrating these utilities requires repetitive programming work. Horde_Cli_Application can facilitate putting the different parts together to an actual application that does something.