`nix search` writes excessive diagnostics to stderr

[rptb1]

Describe the bug

When run in an Emacs shell buffer, a command like nix search nixpkgs 'llama\.?cpp' produces over 117000 lines of output about "evaluating".

A very similar problem happens over ssh, for example ssh localhost nix search nixpkgs 'llama\.?cpp' sends over 117000 lines to the terminal.

In either case, this extra diagnostic output obscures the search results and consumes a lot of bandwidth over a remote connection.

Steps To Reproduce

Debian 13 with apt-get install -y nix-setup-systemd emacs and experimental-features = nix-command flakes in ~/.nix/nix.conf .

1. Launch Terminal
2. ssh localhost nix search nixpkgs 'llama\.?cpp'

or

1. Launch Emacs.
2. M-x shell
3. nix search nixpkgs 'llama\.?cpp'

Expected behavior

Just the search results unless there is an error.

Metadata

nix-env (Nix) 2.26.3

Additional context

Checklist

• checked [latest Nix manual] ([source])
• checked [open bug issues and pull requests] for possible duplicates

[xokdvium]

As a workaround, you can try with --log-format raw. In general, the progress bar does write quite a bit stuff to stderr and we should reduce that if possible.

[rptb1]

Thanks I'll try that.

To clarify, I see no progress bar even running locally in a terminal, just flickering overwritten lines.

And you probably want things to work correctly over SSH when attached to a pty, so it's not just a matter of quantity.

[xokdvium]

just flickering overwritten lines.

Yeah, the activities for nix search is pretty dubious, maybe we should remove those since they mostly provide noise and no substance.

[lisanna-dettwyler]

Maybe we can just change the log level of the evaluating '%s' message in search.cc and flake.cc to lvlTalkative?