tracelinks: init at 1.0.1

[limeytexan]

The tracelinks command accepts a list of paths and traverses each one in turn, reporting on symbolic links encountered along the way and flagging dangling and circular links as errors. When reporting the final element encountered in the path traversal tracelinks prints the realpath of the file along with its file type.

It is particularly useful when identifying packages accessed by way of Nix profiles, e.g.

$ result/bin/tracelinks `which nixos-rebuild`
/run/current-system -> /nix/store/811611n5fspjl1v65grsf3wzbflrm2jm-nixos-system-treehouse-25.05.20250121.9e4d519
  /nix/store/811611n5fspjl1v65grsf3wzbflrm2jm-nixos-system-treehouse-25.05.20250121.9e4d519/sw -> /nix/store/0w3p8z0100xidzx2dr2mkjp1ijgz75f3-system-path
    /nix/store/0w3p8z0100xidzx2dr2mkjp1ijgz75f3-system-path/bin/nixos-rebuild -> /nix/store/jdjxinr65v0hp1pb6jk1vdvp97azspgc-nixos-rebuild/bin/nixos-rebuild
      /nix/store/jdjxinr65v0hp1pb6jk1vdvp97azspgc-nixos-rebuild/bin/nixos-rebuild: regular file

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[limeytexan]

Thanks @nayeko for the quick review! Squashed your suggestions and updated the summary of the PR and commit to "tracelinks: init at 1.0.1".