brew list with "License" field - do I have non-free software installed?

[GETandSELECT]

I wish to see an overview of all formula I installed and their license. brew list with license tag.

Goal is to see if I installed proprietary / non-free software.

brew info prometheus
prometheus: stable 2.21.0 (bottled)
Service monitoring system and time series database
https://prometheus.io/
Not installed
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/prometheus.rb
License: Apache-2.0

[gromgit]

The first paragraph of https://docs.brew.sh/License-Guidelines reads:

We only accept formulae that use a Debian Free Software Guidelines license or are released into the public domain following DFSG Guidelines on Public Domain software.

So if you only use the core tap, your result set is guaranteed to be empty.

If you use third-party taps, there's no guarantee that they have license stanzas, but a fairly simple way to get the info you want involves jq:

brew info --json --installed | jq -r '.[] | [.name, .license] | @tsv' | while IFS=$'\t' read name license; do
  # Check $license for non-free indicators
  ...
done

[brettp]

This doesn't work because there's no verification or requirements for the license field.

Multiple known OSS in the default cask repo don't have a license field (see Blender, Gimp, Audacity).

Commercial software also fails this test for the same reason. See the recently added Limitless commercial and proprietary SaaS AI service as an example.

There's unfortunately no way to check if you're using only OSS software in Homebrew without checking each project's individual license from their own source or website (since commercial and non-licensed software is allowed in casks).

[SMillerDev]

Casks don't have a license since there is no requirement for them to have one to be included. In addition to that, they are often proprietary and hard to represent in a simple statement.

[SMillerDev]

There's unfortunately no way to check if you're using only OSS software in Homebrew

There is a simple one: do you install software outside of Homebrew/core? You then you probably have non-OSS software installed

[brettp]

Thank you for the confirmation. My point is the selected answer doesn't work because the license field is not required and in addition to proprietary, many open source projects don't even use it.

The field is essentially unreliable and not an accurate representation, so either wouldn't be an answer to OP's question, or should be enforced to be present and accurate.

[SMillerDev]

That's not accurate, OP asked about Formula. Within the Homebrew organisation those only live in Homebrew/core and although they are not enforced for existing Formula, the vast majority of Formula does have it defined.

You brought in casks, but that is not the original question.

[brettp]

Thanks. I do understand there's a technical difference. From a UX perspective, and to the core question OP is asking, it feels like a difference without distinction though. OP's title brew list with "License" field - do I have non-free software installed? doesn't single out formulae, and the tool presents information nearly identically for both casks and formulae.

Just pointing this out because for folks / projects that must confirm licenses, the solution here doesn't work with the most common configurations of the tool.

[GETandSELECT]

After this question, I learned that there are no problematic licenses in core. However, there are a lot of proprietary casks, so I would really like to see a separation between FLOSS and proprietary casks. I would prefer not to use proprietary apps on my desktop. That would be my feature request, have there already been discussions along similar lines?

[p-linnane]

It would be easiest for you to assume that casks are proprietary and not open source. There are some exceptions to this, but given the overwhelming majority of casks are proprietary, it's a safe bet.