diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index ca712613e4..d234adabc7 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -85,16 +85,14 @@ begin
   ENV["PATH"] = path
 
   require "commands"
+  require "settings"
 
   if cmd
     internal_cmd = Commands.valid_internal_cmd?(cmd)
     internal_cmd ||= begin
       internal_dev_cmd = Commands.valid_internal_dev_cmd?(cmd)
       if internal_dev_cmd && !Homebrew::EnvConfig.developer?
-        if (HOMEBREW_REPOSITORY/".git/config").exist?
-          system "git", "config", "--file=#{HOMEBREW_REPOSITORY}/.git/config",
-                 "--replace-all", "homebrew.devcmdrun", "true"
-        end
+        Settings.write "devcmdrun", true
         ENV["HOMEBREW_DEV_CMD_RUN"] = "1"
       end
       internal_dev_cmd
diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index f38b341394..3a91124812 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -8,6 +8,7 @@ require "descriptions"
 require "cleanup"
 require "description_cache_store"
 require "cli/parser"
+require "settings"
 
 module Homebrew
   extend T::Sig
@@ -63,16 +64,12 @@ module Homebrew
       Utils::Analytics.messages_displayed! if $stdout.tty?
     end
 
-    HOMEBREW_REPOSITORY.cd do
-      donation_message_displayed =
-        Utils.popen_read("git", "config", "--get", "homebrew.donationmessage").chomp == "true"
-      if !donation_message_displayed && !args.quiet?
-        ohai "Homebrew is run entirely by unpaid volunteers. Please consider donating:"
-        puts "  #{Formatter.url("https://github.com/Homebrew/brew#donations")}\n"
+    if Settings.read("donationmessage") != "true" && !args.quiet?
+      ohai "Homebrew is run entirely by unpaid volunteers. Please consider donating:"
+      puts "  #{Formatter.url("https://github.com/Homebrew/brew#donations")}\n"
 
-        # Consider the message possibly missed if not a TTY.
-        safe_system "git", "config", "--replace-all", "homebrew.donationmessage", "true" if $stdout.tty?
-      end
+      # Consider the message possibly missed if not a TTY.
+      Settings.write "donationmessage", true if $stdout.tty?
     end
 
     install_core_tap_if_necessary
@@ -89,19 +86,14 @@ module Homebrew
       puts "Updated Homebrew from #{shorten_revision(initial_revision)} to #{shorten_revision(current_revision)}."
       updated = true
 
-      old_tag = if (HOMEBREW_REPOSITORY/".git/config").exist?
-        Utils.popen_read(
-          "git", "config", "--file=#{HOMEBREW_REPOSITORY}/.git/config", "--get", "homebrew.latesttag"
-        ).chomp.presence
-      end
+      old_tag = Settings.read "latesttag"
 
       new_tag = Utils.popen_read(
         "git", "-C", HOMEBREW_REPOSITORY, "tag", "--list", "--sort=-version:refname", "*.*"
       ).lines.first.chomp
 
       if new_tag != old_tag
-        system "git", "config", "--file=#{HOMEBREW_REPOSITORY}/.git/config",
-               "--replace-all", "homebrew.latesttag", new_tag
+        Settings.write "latesttag", new_tag
         new_repository_version = new_tag
       end
     end
diff --git a/Library/Homebrew/completions.rb b/Library/Homebrew/completions.rb
index 9bde547f40..356a9dbabd 100644
--- a/Library/Homebrew/completions.rb
+++ b/Library/Homebrew/completions.rb
@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require "utils/link"
+require "settings"
 
 # Helper functions for generating shell completions.
 #
@@ -13,7 +14,7 @@ module Completions
 
   sig { void }
   def link!
-    write_completions_option "yes"
+    Settings.write :linkcompletions, true
     Tap.each do |tap|
       Utils::Link.link_completions tap.path, "brew completions link"
     end
@@ -21,7 +22,7 @@ module Completions
 
   sig { void }
   def unlink!
-    write_completions_option "no"
+    Settings.write :linkcompletions, false
     Tap.each do |tap|
       next if tap.official?
 
@@ -31,7 +32,7 @@ module Completions
 
   sig { returns(T::Boolean) }
   def link_completions?
-    read_completions_option == "yes"
+    Settings.read(:linkcompletions) == "true"
   end
 
   sig { returns(T::Boolean) }
@@ -48,23 +49,9 @@ module Completions
     false
   end
 
-  sig { params(option: String).returns(String) }
-  def read_completions_option(option: "linkcompletions")
-    HOMEBREW_REPOSITORY.cd do
-      Utils.popen_read("git", "config", "--get", "homebrew.#{option}").chomp
-    end
-  end
-
-  sig { params(state: String, option: String).void }
-  def write_completions_option(state, option: "linkcompletions")
-    HOMEBREW_REPOSITORY.cd do
-      T.unsafe(self).safe_system "git", "config", "--replace-all", "homebrew.#{option}", state.to_s
-    end
-  end
-
   sig { void }
   def show_completions_message_if_needed
-    return if read_completions_option(option: "completionsmessageshown") == "yes"
+    return if Settings.read(:completionsmessageshown) == "true"
     return unless completions_to_link?
 
     T.unsafe(self).ohai "Homebrew completions for external commands are unlinked by default!"
@@ -74,6 +61,6 @@ module Completions
       Then, follow the directions at #{Formatter.url("https://docs.brew.sh/Shell-Completion")}
     EOS
 
-    write_completions_option("yes", option: "completionsmessageshown")
+    Settings.write :completionsmessageshown, true
   end
 end
diff --git a/Library/Homebrew/settings.rb b/Library/Homebrew/settings.rb
new file mode 100644
index 0000000000..24286026ac
--- /dev/null
+++ b/Library/Homebrew/settings.rb
@@ -0,0 +1,39 @@
+# typed: true
+# frozen_string_literal: true
+
+# Helper functions for reading and writing settings.
+#
+# @api private
+module Settings
+  extend T::Sig
+
+  module_function
+
+  sig { params(setting: T.any(String, Symbol), repo: Pathname).returns(T.nilable(String)) }
+  def read(setting, repo: HOMEBREW_REPOSITORY)
+    return unless (repo/".git/config").exist?
+
+    repo.cd do
+      Utils.popen_read("git", "config", "--get", "homebrew.#{setting}").chomp.presence
+    end
+  end
+
+  sig { params(setting: T.any(String, Symbol), value: T.any(String, T::Boolean), repo: Pathname).void }
+  def write(setting, value, repo: HOMEBREW_REPOSITORY)
+    return unless (repo/".git/config").exist?
+
+    repo.cd do
+      T.unsafe(self).safe_system "git", "config", "--replace-all", "homebrew.#{setting}", value.to_s
+    end
+  end
+
+  sig { params(setting: T.any(String, Symbol), repo: Pathname).void }
+  def delete(setting, repo: HOMEBREW_REPOSITORY)
+    return unless (repo/".git/config").exist?
+    return if read(setting, repo: repo).blank?
+
+    repo.cd do
+      T.unsafe(self).safe_system "git", "config", "--unset-all", "homebrew.#{setting}"
+    end
+  end
+end
diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index b8daea201a..b9e90b1686 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -5,6 +5,7 @@ require "commands"
 require "completions"
 require "extend/cachable"
 require "description_cache_store"
+require "settings"
 
 # A {Tap} is used to extend the formulae provided by Homebrew core.
 # Usually, it's synced with a remote Git repository. And it's likely
@@ -821,18 +822,14 @@ class TapConfig
     return unless tap.git?
     return unless Utils::Git.available?
 
-    tap.path.cd do
-      Utils.popen_read("git", "config", "--get", "homebrew.#{key}").chomp.presence
-    end
+    Settings.read key, repo: tap.path
   end
 
   def []=(key, value)
     return unless tap.git?
     return unless Utils::Git.available?
 
-    tap.path.cd do
-      safe_system "git", "config", "--replace-all", "homebrew.#{key}", value.to_s
-    end
+    Settings.write key, value.to_s, repo: tap.path
   end
 end
 
diff --git a/Library/Homebrew/test/completions_spec.rb b/Library/Homebrew/test/completions_spec.rb
new file mode 100644
index 0000000000..41c9f95ef0
--- /dev/null
+++ b/Library/Homebrew/test/completions_spec.rb
@@ -0,0 +1,143 @@
+# typed: false
+# frozen_string_literal: true
+
+require "completions"
+
+describe Completions do
+  let(:internal_path) { HOMEBREW_REPOSITORY/"Library/Taps/homebrew/homebrew-bar" }
+  let(:external_path) { HOMEBREW_REPOSITORY/"Library/Taps/foo/homebrew-bar" }
+
+  before do
+    HOMEBREW_REPOSITORY.cd do
+      system "git", "init"
+    end
+    internal_path.mkpath
+    external_path.mkpath
+  end
+
+  def setup_completions(external:)
+    (internal_path/"completions/bash/foo_internal").write "#foo completions"
+    if external
+      (external_path/"completions/bash/foo_external").write "#foo completions"
+    elsif (external_path/"completions/bash/foo_external").exist?
+      (external_path/"completions/bash/foo_external").delete
+    end
+  end
+
+  def setup_completions_setting(state, setting: "linkcompletions")
+    HOMEBREW_REPOSITORY.cd do
+      system "git", "config", "--replace-all", "homebrew.#{setting}", state.to_s
+    end
+  end
+
+  def read_completions_setting(setting: "linkcompletions")
+    HOMEBREW_REPOSITORY.cd do
+      Utils.popen_read("git", "config", "--get", "homebrew.#{setting}").chomp.presence
+    end
+  end
+
+  def delete_completions_setting(setting: "linkcompletions")
+    HOMEBREW_REPOSITORY.cd do
+      system "git", "config", "--unset-all", "homebrew.#{setting}"
+    end
+  end
+
+  after do
+    FileUtils.rm_rf internal_path
+    FileUtils.rm_rf external_path.dirname
+  end
+
+  describe ".link!" do
+    it "sets homebrew.linkcompletions to true" do
+      setup_completions_setting false
+      expect { described_class.link! }.not_to raise_error
+      expect(read_completions_setting).to eq "true"
+    end
+
+    it "sets homebrew.linkcompletions to true if unset" do
+      delete_completions_setting
+      expect { described_class.link! }.not_to raise_error
+      expect(read_completions_setting).to eq "true"
+    end
+
+    it "keeps homebrew.linkcompletions set to true" do
+      setup_completions_setting true
+      expect { described_class.link! }.not_to raise_error
+      expect(read_completions_setting).to eq "true"
+    end
+  end
+
+  describe ".unlink!" do
+    it "sets homebrew.linkcompletions to false" do
+      setup_completions_setting true
+      expect { described_class.unlink! }.not_to raise_error
+      expect(read_completions_setting).to eq "false"
+    end
+
+    it "sets homebrew.linkcompletions to false if unset" do
+      delete_completions_setting
+      expect { described_class.unlink! }.not_to raise_error
+      expect(read_completions_setting).to eq "false"
+    end
+
+    it "keeps homebrew.linkcompletions set to false" do
+      setup_completions_setting false
+      expect { described_class.unlink! }.not_to raise_error
+      expect(read_completions_setting).to eq "false"
+    end
+  end
+
+  describe ".link_completions?" do
+    it "returns true if homebrew.linkcompletions is true" do
+      setup_completions_setting true
+      expect(described_class.link_completions?).to be true
+    end
+
+    it "returns false if homebrew.linkcompletions is false" do
+      setup_completions_setting false
+      expect(described_class.link_completions?).to be false
+    end
+
+    it "returns false if homebrew.linkcompletions is not set" do
+      expect(described_class.link_completions?).to be false
+    end
+  end
+
+  describe ".completions_to_link?" do
+    it "returns false if only internal taps have completions" do
+      setup_completions external: false
+      expect(described_class.completions_to_link?).to be false
+    end
+
+    it "returns true if external taps have completions" do
+      setup_completions external: true
+      expect(described_class.completions_to_link?).to be true
+    end
+  end
+
+  describe ".show_completions_message_if_needed" do
+    it "doesn't show the message if there are no completions to link" do
+      setup_completions external: false
+      delete_completions_setting setting: :completionsmessageshown
+      expect { described_class.show_completions_message_if_needed }.not_to output.to_stdout
+    end
+
+    it "doesn't show the message if there are completions to link but the message has already been shown" do
+      setup_completions external: true
+      setup_completions_setting true, setting: :completionsmessageshown
+      expect { described_class.show_completions_message_if_needed }.not_to output.to_stdout
+    end
+
+    it "shows the message if there are completions to link and the message hasn't already been shown" do
+      setup_completions external: true
+      delete_completions_setting setting: :completionsmessageshown
+
+      # This will fail because the method calls `puts`.
+      # If we output the `ohai` andcatch the error, we can be usre that the message is showing.
+      error_message = "private method `puts' called for Completions:Module"
+      expect { described_class.show_completions_message_if_needed }
+        .to output.to_stdout
+        .and raise_error(NoMethodError, error_message)
+    end
+  end
+end
diff --git a/Library/Homebrew/test/settings_spec.rb b/Library/Homebrew/test/settings_spec.rb
new file mode 100644
index 0000000000..1c42f7fe76
--- /dev/null
+++ b/Library/Homebrew/test/settings_spec.rb
@@ -0,0 +1,74 @@
+# typed: false
+# frozen_string_literal: true
+
+require "settings"
+
+describe Settings do
+  before do
+    HOMEBREW_REPOSITORY.cd do
+      system "git", "init"
+    end
+  end
+
+  def setup_setting
+    HOMEBREW_REPOSITORY.cd do
+      system "git", "config", "--replace-all", "homebrew.foo", "true"
+    end
+  end
+
+  describe ".read" do
+    it "returns the correct value for a setting" do
+      setup_setting
+      expect(described_class.read("foo")).to eq "true"
+    end
+
+    it "returns the correct value for a setting as a symbol" do
+      setup_setting
+      expect(described_class.read(:foo)).to eq "true"
+    end
+
+    it "returns nil when setting is not set" do
+      setup_setting
+      expect(described_class.read("bar")).to be_nil
+    end
+
+    it "runs on a repo without a configuration file" do
+      expect { described_class.read("foo", repo: HOMEBREW_REPOSITORY/"bar") }.not_to raise_error
+    end
+  end
+
+  describe ".write" do
+    it "writes over an existing value" do
+      setup_setting
+      described_class.write :foo, false
+      expect(described_class.read("foo")).to eq "false"
+    end
+
+    it "writes a new value" do
+      setup_setting
+      described_class.write :bar, "abcde"
+      expect(described_class.read("bar")).to eq "abcde"
+    end
+
+    it "returns if the repo doesn't have a configuration file" do
+      expect { described_class.write("foo", repo: HOMEBREW_REPOSITORY/"bar") }.not_to raise_error
+    end
+  end
+
+  describe ".delete" do
+    it "deletes an existing setting" do
+      setup_setting
+      described_class.delete(:foo)
+      expect(described_class.read("foo")).to be_nil
+    end
+
+    it "deletes a non-existing setting" do
+      setup_setting
+      expect { described_class.delete(:bar) }.not_to raise_error
+    end
+
+    it "returns if the repo doesn't have a configuration file" do
+      expect { described_class.delete("foo", repo: HOMEBREW_REPOSITORY/"bar") }.not_to raise_error
+    end
+  end
+end
diff --git a/Library/Homebrew/test/tap_spec.rb b/Library/Homebrew/test/tap_spec.rb
index eb4a64e121..691e5fa61c 100644
--- a/Library/Homebrew/test/tap_spec.rb
+++ b/Library/Homebrew/test/tap_spec.rb
@@ -87,8 +87,8 @@ describe Tap do
   def setup_completion(link:)
     HOMEBREW_REPOSITORY.cd do
       system "git", "init"
-      system "git", "config", "--replace-all", "homebrew.linkcompletions", link
-      system "git", "config", "--replace-all", "homebrew.completionsmessageshown", "yes"
+      system "git", "config", "--replace-all", "homebrew.linkcompletions", link.to_s
+      system "git", "config", "--replace-all", "homebrew.completionsmessageshown", "true"
     end
   end
 
@@ -293,7 +293,7 @@ describe Tap do
   specify "#install and #uninstall" do
     setup_tap_files
     setup_git_repo
-    setup_completion link: "yes"
+    setup_completion link: true
 
     tap = described_class.new("Homebrew", "bar")
 
@@ -320,7 +320,7 @@ describe Tap do
   specify "#link_completions_and_manpages when completions are enabled for non-official tap" do
     setup_tap_files
     setup_git_repo
-    setup_completion link: "yes"
+    setup_completion link: true
     tap = described_class.new("NotHomebrew", "baz")
     tap.install clone_target: subject.path/".git"
     (HOMEBREW_PREFIX/"share/man/man1/brew-tap-cmd.1").delete
@@ -341,7 +341,7 @@ describe Tap do
   specify "#link_completions_and_manpages when completions are disabled for non-official tap" do
     setup_tap_files
     setup_git_repo
-    setup_completion link: "no"
+    setup_completion link: false
     tap = described_class.new("NotHomebrew", "baz")
     tap.install clone_target: subject.path/".git"
     (HOMEBREW_PREFIX/"share/man/man1/brew-tap-cmd.1").delete
@@ -359,7 +359,7 @@ describe Tap do
   specify "#link_completions_and_manpages when completions are enabled for official tap" do
     setup_tap_files
     setup_git_repo
-    setup_completion link: "no"
+    setup_completion link: false
     tap = described_class.new("Homebrew", "baz")
     tap.install clone_target: subject.path/".git"
     (HOMEBREW_PREFIX/"share/man/man1/brew-tap-cmd.1").delete
diff --git a/Library/Homebrew/utils/analytics.rb b/Library/Homebrew/utils/analytics.rb
index 6dca9a2001..9ab040159d 100644
--- a/Library/Homebrew/utils/analytics.rb
+++ b/Library/Homebrew/utils/analytics.rb
@@ -3,6 +3,7 @@
 
 require "context"
 require "erb"
+require "settings"
 
 module Utils
   # Helper module for fetching and reporting analytics data.
@@ -102,27 +103,27 @@ module Utils
       end
 
       def uuid
-        config_get(:analyticsuuid)
+        Settings.read :analyticsuuid
       end
 
       def messages_displayed!
-        config_set(:analyticsmessage, true)
-        config_set(:caskanalyticsmessage, true)
+        Settings.write :analyticsmessage, true
+        Settings.write :caskanalyticsmessage, true
       end
 
       def enable!
-        config_set(:analyticsdisabled, false)
+        Settings.write :analyticsdisabled, false
         messages_displayed!
       end
 
       def disable!
-        config_set(:analyticsdisabled, true)
+        Settings.write :analyticsdisabled, true
         regenerate_uuid!
       end
 
       def regenerate_uuid!
         # it will be regenerated in next run unless disabled.
-        config_delete(:analyticsuuid)
+        Settings.delete :analyticsuuid
       end
 
       def output(args:, filter: nil)
@@ -313,25 +314,7 @@ module Utils
       end
 
       def config_true?(key)
-        config_get(key) == "true"
-      end
-
-      def config_get(key)
-        HOMEBREW_REPOSITORY.cd do
-          Utils.popen_read("git", "config", "--get", "homebrew.#{key}").chomp
-        end
-      end
-
-      def config_set(key, value)
-        HOMEBREW_REPOSITORY.cd do
-          safe_system "git", "config", "--replace-all", "homebrew.#{key}", value.to_s
-        end
-      end
-
-      def config_delete(key)
-        HOMEBREW_REPOSITORY.cd do
-          system "git", "config", "--unset-all", "homebrew.#{key}"
-        end
+        Settings.read(key) == "true"
       end
 
       def formulae_brew_sh_json(endpoint)