pynom - Python Nix Output Monitor

A Python clone of nix-output-monitor that provides live, informative terminal output for Nix builds and related commands.

Features

• Live status box for subcommands like build, profile, home, and os
• Persistent scrollback logs for build output and recent activity
• Progress tracking for builds, downloads, and uploads
• Time estimates based on historical build data
• JSON log support for modern nix build commands
• Drop-in replacement for nix build, nix profile, home-manager, and nixos-rebuild

Installation

pip install pynom
# or with nix:
nix profile install .

Usage

As a drop-in replacement

# Instead of: nix build .#something
pynom build .#something

# Instead of: nix profile upgrade
pynom profile upgrade hello

# Instead of: home-manager switch
pynom home switch

# Instead of: nixos-rebuild switch
pynom os switch

# Instead of: nix shell
pynom shell nixpkgs#hello

# Instead of: nix develop
pynom develop

Piping output

# Old-style nix-build
nix-build 2>&1 | pynom

# New-style with JSON logs (recommended)
nix build .#something --log-format internal-json -v 2>&1 | pynom --json

# Works with nixos-rebuild, home-manager, etc.
nixos-rebuild switch 2>&1 | pynom

Display behavior

• Subcommands use the live TUI by default.
• In live TUI mode, the box shows current status and progress.
• Build logs and recent activity are printed once into scrollback instead of being redrawn inside the box.
• Pipe mode stays stream-oriented by default; use pynom --tui if you want the live box there too.

How it works

1. Parses Nix build output (human-readable or JSON format)
2. Tracks build dependencies and their status
3. Displays a live status box and keeps logs in normal terminal scrollback
4. Stores build times for future predictions

Comparison to original

This is a Python reimplementation inspired by the Haskell nix-output-monitor. It aims for feature parity with a simpler codebase.