Every package is already installed

Omnibin is a FUSE filesystem that allows access to every binary that has ever been released by nixpkgs without the need for installation. These binaries are loaded on-demand and do not occupy disk space until they are actually accessed. This innovative approach to package management was inspired by a keynote at RailsConf 2026, where the presenter expressed frustration with the traditional process of adding packages to configuration.nix and running nix-shell.

With omnibin, there is no need to decide which packages to install – all of the available packages from Nixpkgs are available on the $PATH. The system achieves this by crawling the .ls files in the Nix cache, which provide a metadata index of the contents of every archive. This index is used to create the omnibin filesystem, which allows for lazy loading of the necessary NARs when a binary is accessed.

The result is a powerful and efficient package management system that eliminates the need for individual package installation, while still maintaining the ability to access specific versions of packages as needed.