Nix Package Manager: Installation and System Changes Analysis

January 02, 2025

沒什麼組織、一些倏忽即逝有趣或不有趣的想法

Nix 初探
- Installation - https://nix.dev/install-nix
  - sh <(curl -L https://nixos.org/nix/install)
  - What it does:
    - Install Nix package manager
    - Create a new profile for the current user
    - Add the Nix profile to the user’s shell profile
    - Based on the installation log, here are the critical changes Nix made to your machine:
      - File System Changes: (this is because macOS now (starting in 10.15 Catalina) has a read-only root directory. To support Nix, it will create a volume and configure macOS to mount it at /nix) Created a dedicated encrypted volume called “Nix Store” mounted at /nix Modified /etc/synthetic.conf to create the mount point Modified /etc/fstab to specify volume mount options
      - User and Group Creation: Created a system group called nixbld with GID 350 Created 32 system users (_nixbld1 through _nixbld32) with UIDs 351-382 All build users are: Set to have /var/empty as home directory Disabled from logging in Added to the nixbld group Hidden from the system
      - Directory Structure: Created several directories under /nix, including: install: mkdir /nix/var install: mkdir /nix/var/log install: mkdir /nix/var/log/nix install: mkdir /nix/var/log/nix/drvs install: mkdir /nix/var/nix install: mkdir /nix/var/nix/db install: mkdir /nix/var/nix/gcroots install: mkdir /nix/var/nix/profiles install: mkdir /nix/var/nix/temproots install: mkdir /nix/var/nix/userpool install: mkdir /nix/var/nix/daemon-socket install: mkdir /nix/var/nix/gcroots/per-user install: mkdir /nix/var/nix/profiles/per-user install: mkdir /nix/store install: mkdir /etc/nix
      - Shell Configuration: Backed up and modified shell configuration files: /etc/bashrc /etc/zshrc Added Fish shell configurations Added Nix environment setup scripts to these files (e.g. execute . '/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh')
      - System Services: Created a LaunchDaemon at /Library/LaunchDaemons/org.nixos.nix-daemon.plist Set up a service to automatically mount the Nix volume
      - Package Management: Installed Nix package manager under /nix/store/ Set up the default profile with basic packages including SSL certificates (nss-cacert)
        These changes make Nix work as a separate package manager on macOS, isolated from the rest of your system in its own volume.
- Usage
  - nix-shell -p <package>: Start a shell with the specified package available
  - nix-shell -p <package> --command <command>: Run a command in a shell with the specified package available
  - nix-shell -p <package> --run <command>: Run a command in a shell with the specified package available and exit
  - nix-store --gc: Garbage collect the Nix store to remove unused packages