Show Dependency Reason Current Nixos

Identifies why a specific package is included in the current NixOS system by analyzing dependencies.

Terminal

nix why-depends </run/current-system> /nix/store/<checksum-package-version.ext>

nix why-depends </run/current-system> /nix/store/<checksum-package-version.ext>

#!/bin/bash

# Show Dependency Reason Current Nixos
nix why-depends {{/run/current-system}} /nix/store/{{checksum-package-version.ext}}

import subprocess

# Show Dependency Reason Current Nixos
# Make sure to replace <placeholders> with actual values
def run_command():
    cmd = [
        "nix",
        "why-depends",
        "</run/current-system>",
        "/nix/store/<checksum-package-version.ext>"
    ]
    
    try:
        print(f"Executing: {' '.join(cmd)}")
        subprocess.run(cmd, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error: {e}")
    except FileNotFoundError:
        print("Error: nix not found. Please install it first.")

if __name__ == "__main__":
    run_command()

When To Use

During system integrity verification processes to troubleshoot unexpected package presence in current system.

Pro Tip

Consider using the `--json` flag if you require machine-readable output for automated analysis.

Anatomy of Output

Understanding the result

/nix/store/some-package-1.0.0: dependent on '/nix/store/dependency-2.0.0' (build) Package Path

The absolute path of the analyzed package.

Reason: installed due to 'some meta-package' Reason

Indicates the meta-package influencing this dependency.

Referenced from: /run/current-system Reference Path

The system path where the dependency was identified.

Troubleshooting

Common pitfalls

error: path '/nix/store/invalid-path' does not exist

Solution: Verify the path syntax and ensure the package exists in the Nix store.

error: cannot find derivation for 'nixpkgs#nonexistent-package'

Solution: Check the correctness of the package name or ensure the relevant channel is up-to-date.

error: invalid argument: 'XYZ' is not a valid dependency

Solution: Ensure the provided arguments conform to accepted package naming conventions.

Command Breakdown

What each part is doing

nix: Base Command; The executable that performs this operation. Here it runs Nix before the shell applies any redirect operators.
</run/current-system>: run current system; The value supplied for run current system.
<checksum-package-version.ext>: checksum package version.ext; The value supplied for checksum package version.ext.

Alternative Approaches

Comparable commands in other tools

Alternative package management tools for the same job.

Meteor / List Meteor Packages meteor list Bun / Install Add Single Package bun add <package> Bun / Install Multiple Packages bun add <package1 package2 ...> Bun / Install From Git Repository bun add <git_url> Bun / Install Specific Version bun add <package>@<version>

Show Dependency Reason Current Nixos

Understanding the result

Common pitfalls

What each part is doing

Stay inside the same tool family

Comparable commands in other tools