What is the difference between brew list --installed-on-request and brew leaves --installed-on-request?

[nbro]

Output of brew config

HOMEBREW_VERSION: 4.2.20
ORIGIN: https://github.com/Homebrew/brew
HEAD: c2ed3327c605c3e738359c9807b8f4cd6fec09eb
Last commit: 2 days ago
Core tap HEAD: 909536f5dbfda87216933bb641a8e81fc8f62bae
Core tap last commit: 46 minutes ago
Core tap JSON: 01 May 13:55 UTC
Core cask tap HEAD: 63ffb145a8c06092692969cf9ddfa5d5b6c5954b
Core cask tap last commit: 2 hours ago
Core cask tap JSON: 01 May 13:55 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 3.1.4 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.1.4/bin/ruby
CPU: octa-core 64-bit haswell
Clang: 13.1.6 build 1316
Git: 2.32.1 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 12.7.4-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: 13.4.1

Output of brew doctor

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Description of issue

I originally thought that to get the list of packages I explicitly asked brew to install I should use brew leaves --installed-on-request, but today I realised that brew list also has the flag --installed-on-request.

So, what is the difference between brew list --installed-on-request and brew leaves --installed-on-request?

If I run them, I get different outputs, so they must be doing something different, but what?

Also, if brew list --installed-on-request shows the packages that I explicitly installed, what's the purpose of brew leaves? In general, what's the purpose of this brew leaves command? Couldn't it just be merged with brew list? What do the "leaves" refer to?

[ZhongRuoyu]

brew leaves shows the formulae that are not dependencies of any other formula or cask. So, if you installed package A on request, but A is also a dependency of some other package B, then A will not show up in the output of brew leaves --installed-on-request (but it should be in the output of brew list --installed-on-request).

I originally thought that to get the list of packages I explicitly asked brew to install I should use brew leaves --installed-on-request

brew list --installed-on-request should be what you want here.

[nbro]

@ZhongRuoyu Thanks for answer. But couldn't leaves be merged into list? Why have to separate commands? brew list could have a flag --leaves. Have you considered that? I'm asking because in my view I don't see why leaves should really be a separate command, but maybe I'm missing some context and, anyway, it doesn't hurt too much

[ZhongRuoyu]

I agree with you that brew list --leaves would look better, but brew leaves has existed for too long (Homebrew/legacy-homebrew@3d933c3) so it's not going to be removed.

Perhaps coincidentally, this was also raised recently in Homebrew/brew#17117 (comment).