nix3-develop:tldr:1013a

The command nix develop ${nixpkgs#pkg} is using the Nix package manager to create a development environment for a specific package.

Here is a breakdown of the command:

• nixpkgs: It refers to a Nix repository or channel that contains a collection of packages.
• ${nixpkgs#pkg}: The #pkg syntax is used to refer to a specific package within the Nixpkgs repository. In this case, it is referring to a specific package named pkg. The # symbol is used for matching package names.
• nix develop: It is a subcommand provided by the Nix package manager. This subcommand creates a development environment based on the specified package. It sets up the necessary dependencies and environment variables required to develop or build the specified package.

Overall, the command creates a development environment for a specific package, where all the required dependencies and tools are set up, allowing you to effectively work with that package.