nix-env:tldr:3da45

The command "nix-env -iA nixpkgs.${pkg_name}" is used to install a specific package named "${pkg_name}" from the Nix package collection (nixpkgs).

Here's a breakdown of the command:

• "nix-env" is the Nix package manager's command-line tool for managing packages on a Nix-based system.
• "-i" or "--install" is an option that instructs "nix-env" to install the specified package(s).
• "-A" or "--attr" is an option that expects an attribute name as an argument. It specifies the attribute in the Nixpkgs collection to install.
• "nixpkgs.${pkg_name}" is an attribute reference for the specific package named "${pkg_name}" in the Nixpkgs collection. By using this syntax, you are specifying the package as an attribute in the "nixpkgs" set.

For example, if you want to install the package named "firefox" from Nixpkgs, you would replace "${pkg_name}" with "firefox" and run the command:

nix-env -iA nixpkgs.firefox

This will install the "firefox" package onto your system using the Nix package manager.