[rawsun007]

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• I did not use AI/LLM to create this PR, or I disclosed the tool/model below and reviewed its output; I did not attribute commits to AI and will answer maintainer questions and review comments myself without AI/LLM.

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Utils::Shell.set_variable_in_profile and prepend_path_in_profile build a command the user is told to paste. Every branch wraps the profile line in echo '...' except the PowerShell one, which redirects the assignment itself:

"$env:#{variable}='#{value}' >> #{profile}"
"$env:PATH = '#{path}' + \":${env:PATH}\" >> #{profile}"

>> binds to the pipeline, so PowerShell parses those as $env:X = ('y' >> profile). The assignment gets the redirection's result, which is null, and the profile receives the bare value.

Against PowerShell 7.4.6 on macOS, running what brew currently prints:

PS> $env:HOMEBREW_FOO = 'bar' >> ./prof.ps1
PS> $env:HOMEBREW_FOO
                                  # empty
PS> Get-Content ./prof.ps1
bar

The PATH one is worse, because it also blanks $env:PATH in the running session and writes the expanded path as a bare line. Sourcing the profile afterwards gives:

The term '/opt/homebrew/bin:/usr/bin:…' is not recognized as a name of a cmdlet,
function, script file, or executable program.

So a PowerShell user following brew's own advice ends up with a profile that errors on every start and never sets the variable.

To reproduce from brew: with SHELL=/usr/bin/pwsh, brew link on a keg-only formula prints the prepend_path_in_profile command, and brew --env/brew doctor paths print the set_variable_in_profile one.

The fix emits the line as a quoted string, matching what the other branches do with echo. pwsh_quote sits alongside sh_quote and csh_quote; PowerShell single-quoted strings only treat ' specially (doubled), so $, " and backticks need nothing. After the fix, the same session:

PS> '$env:HOMEBREW_FOO = ''bar''''s "x" $y''' >> ./prof.ps1
PS> . ./prof.ps1
PS> $env:HOMEBREW_FOO
bar's "x" $y

Not touched: Utils::Shell.export_value still has no pwsh branch and returns nil there, so brew --env --shell=pwsh and the caveats blocks print nothing for PowerShell users. That is a missing feature rather than a wrong command, and cmd/shellenv.sh already handles pwsh separately, so it looked like its own change.

brew lgtm is green, and reverting only utils/shell.rb fails exactly the three new examples.

AI disclosure: the diff, the tests and the PowerShell verification above were produced by Claude Opus 5 in Claude Code on my machine. I have not yet read the diff line by line myself, so the last box stays unticked until I have; I answer review comments myself, and no commit here is attributed to an AI.

[MikeMcQuaid]

Thanks!