From 3f96d963f7a2e5ff0f084bcb16e7f95e5aa72cfd Mon Sep 17 00:00:00 2001
From: XuehaiPan <XuehaiPan@pku.edu.cn>
Date: Mon, 13 Sep 2021 20:32:20 +0800
Subject: [PATCH] style: fix inconsistent code style for shell scripts

---
 .github/workflows/docker.yml                  |  20 +--
 .github/workflows/sorbet.yml                  |  17 +-
 .github/workflows/spdx.yml                    |  17 +-
 .github/workflows/tests.yml                   |  21 +--
 .github/workflows/update-man-completions.yml  |  26 ++--
 .github/workflows/vendor-gems.yml             |   9 +-
 .vscode/settings.json                         |   2 +-
 Dockerfile                                    |   2 +-
 Library/Homebrew/brew.sh                      | 146 +++++++++++-------
 Library/Homebrew/cask/utils/rmdir.sh          |  21 ++-
 Library/Homebrew/cmd/--version.sh             |  11 +-
 Library/Homebrew/cmd/shellenv.sh              |   6 +-
 Library/Homebrew/cmd/update-reset.sh          |   6 +-
 Library/Homebrew/cmd/update.sh                | 115 +++++++-------
 Library/Homebrew/cmd/vendor-install.sh        |  52 ++++---
 Library/Homebrew/dev-cmd/rubocop.sh           |   3 +-
 Library/Homebrew/items.sh                     |  25 +--
 Library/Homebrew/prefix.sh                    |  31 ++--
 Library/Homebrew/shims/linux/super/make       |  20 ++-
 Library/Homebrew/shims/mac/super/pkg-config   |   3 +-
 Library/Homebrew/shims/mac/super/ruby         |   5 +-
 Library/Homebrew/shims/mac/super/swift        |   5 +-
 Library/Homebrew/shims/mac/super/xcrun        |  46 +++---
 Library/Homebrew/shims/scm/git                |   4 +-
 Library/Homebrew/shims/super/cc               |   4 +-
 Library/Homebrew/shims/utils.sh               |  33 ++--
 Library/Homebrew/utils/analytics.sh           |   4 +-
 Library/Homebrew/utils/lock.sh                |   2 +-
 Library/Homebrew/utils/ruby.sh                |  17 +-
 bin/brew                                      |   2 +-
 docs/Common-Issues.md                         |   6 +-
 docs/FAQ.md                                   |   4 +-
 docs/Formula-Cookbook.md                      |   2 +-
 docs/Gems,-Eggs-and-Perl-Modules.md           |   2 +-
 docs/Homebrew-and-Python.md                   |   2 +-
 ...omebrew-linuxbrew-core-Maintainer-Guide.md |  11 +-
 docs/Homebrew-on-Linux.md                     |  10 +-
 docs/How-To-Open-a-Homebrew-Pull-Request.md   |   4 +-
 ...rew-with-Homebrew-keg-only-Dependencies.md |   8 +-
 docs/Manpage.md                               |   2 +-
 docs/Shell-Completion.md                      |  18 ++-
 docs/Tips-N'-Tricks.md                        |   4 +-
 manpages/brew.1                               |   4 +-
 43 files changed, 421 insertions(+), 331 deletions(-)

diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index b74e53d2df..a1c2b3252c 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -34,11 +34,11 @@ jobs:
       - name: Deploy the tagged Docker image to GitHub Packages
         if: startsWith(github.ref, 'refs/tags/')
         run: |
-          brew_version=${GITHUB_REF:10}
-          echo "brew_version=$brew_version" >> ${GITHUB_ENV}
+          brew_version="${GITHUB_REF:10}"
+          echo "brew_version=${brew_version}" >> "${GITHUB_ENV}"
           echo ${{secrets.HOMEBREW_BREW_GITHUB_PACKAGES_TOKEN}} | docker login ghcr.io -u BrewTestBot --password-stdin
-          docker tag brew "ghcr.io/homebrew/ubuntu${{matrix.version}}:$brew_version"
-          docker push "ghcr.io/homebrew/ubuntu${{matrix.version}}:$brew_version"
+          docker tag brew "ghcr.io/homebrew/ubuntu${{matrix.version}}:${brew_version}"
+          docker push "ghcr.io/homebrew/ubuntu${{matrix.version}}:${brew_version}"
           docker tag brew "ghcr.io/homebrew/ubuntu${{matrix.version}}:latest"
           docker push "ghcr.io/homebrew/ubuntu${{matrix.version}}:latest"
 
@@ -46,19 +46,19 @@ jobs:
         if: startsWith(github.ref, 'refs/tags/')
         run: |
           echo ${{secrets.HOMEBREW_BREW_DOCKER_TOKEN}} | docker login -u brewtestbot --password-stdin
-          docker tag brew "homebrew/ubuntu${{matrix.version}}:$brew_version"
-          docker push "homebrew/ubuntu${{matrix.version}}:$brew_version"
+          docker tag brew "homebrew/ubuntu${{matrix.version}}:${brew_version}"
+          docker push "homebrew/ubuntu${{matrix.version}}:${brew_version}"
           docker tag brew "homebrew/ubuntu${{matrix.version}}:latest"
           docker push "homebrew/ubuntu${{matrix.version}}:latest"
 
       - name: Deploy the homebrew/brew Docker image to GitHub Packages and Docker Hub
         if: startsWith(github.ref, 'refs/tags/') && matrix.version == '20.04'
         run: |
-          docker tag brew "ghcr.io/homebrew/brew:$brew_version"
-          docker push "ghcr.io/homebrew/brew:$brew_version"
+          docker tag brew "ghcr.io/homebrew/brew:${brew_version}"
+          docker push "ghcr.io/homebrew/brew:${brew_version}"
           docker tag brew "ghcr.io/homebrew/brew:latest"
           docker push "ghcr.io/homebrew/brew:latest"
-          docker tag brew "homebrew/brew:$brew_version"
-          docker push "homebrew/brew:$brew_version"
+          docker tag brew "homebrew/brew:${brew_version}"
+          docker push "homebrew/brew:${brew_version}"
           docker tag brew "homebrew/brew:latest"
           docker push "homebrew/brew:latest"
diff --git a/.github/workflows/sorbet.yml b/.github/workflows/sorbet.yml
index ff8b18b8a8..93e93856dd 100644
--- a/.github/workflows/sorbet.yml
+++ b/.github/workflows/sorbet.yml
@@ -40,20 +40,23 @@ jobs:
           BRANCH="sorbet-files-update"
           echo "::set-output name=branch::${BRANCH}"
 
-          if git ls-remote --exit-code --heads origin "$BRANCH"; then
-            git checkout "$BRANCH"
+          if git ls-remote --exit-code --heads origin "${BRANCH}"
+          then
+            git checkout "${BRANCH}"
             git reset --hard origin/master
           else
-            git checkout --no-track -B "$BRANCH" origin/master
+            git checkout --no-track -B "${BRANCH}" origin/master
           fi
 
-          if brew typecheck --update --fail-if-not-changed; then
-            git add "$GITHUB_WORKSPACE/Library/Homebrew/sorbet"
+          if brew typecheck --update --fail-if-not-changed
+          then
+            git add "${GITHUB_WORKSPACE}/Library/Homebrew/sorbet"
             git commit -m "sorbet: Update RBI files." \
                        -m "Autogenerated by the [sorbet](https://github.com/Homebrew/brew/blob/master/.github/workflows/sorbet.yml) workflow."
             echo "::set-output name=committed::true"
-            PULL_REQUEST_STATE=$(gh pr view --json=state | jq -r ".state")
-            if [ "$PULL_REQUEST_STATE" != "OPEN" ]; then
+            PULL_REQUEST_STATE="$(gh pr view --json=state | jq -r ".state")"
+            if [[ "${PULL_REQUEST_STATE}" != "OPEN" ]]
+            then
               echo "::set-output name=pull_request::true"
             fi
           fi
diff --git a/.github/workflows/spdx.yml b/.github/workflows/spdx.yml
index 3797770d1b..93b3504f7d 100644
--- a/.github/workflows/spdx.yml
+++ b/.github/workflows/spdx.yml
@@ -37,19 +37,22 @@ jobs:
           BRANCH="spdx-update"
           echo "::set-output name=branch::${BRANCH}"
 
-          if git ls-remote --exit-code --heads origin "$BRANCH"; then
-            git checkout "$BRANCH"
+          if git ls-remote --exit-code --heads origin "${BRANCH}"
+          then
+            git checkout "${BRANCH}"
             git reset --hard origin/master
           else
-            git checkout --no-track -B "$BRANCH" origin/master
+            git checkout --no-track -B "${BRANCH}" origin/master
           fi
 
-          if brew update-license-data --fail-if-not-changed; then
-            git add "$GITHUB_WORKSPACE/Library/Homebrew/data/spdx"
+          if brew update-license-data --fail-if-not-changed
+          then
+            git add "${GITHUB_WORKSPACE}/Library/Homebrew/data/spdx"
             git commit -m "spdx: update license data." -m "Autogenerated by [a scheduled GitHub Action](https://github.com/Homebrew/brew/blob/master/.github/workflows/spdx.yml)."
             echo "::set-output name=committed::true"
-            PULL_REQUEST_STATE=$(gh pr view --json=state | jq -r ".state")
-            if [ "$PULL_REQUEST_STATE" != "OPEN" ]; then
+            PULL_REQUEST_STATE="$(gh pr view --json=state | jq -r ".state")"
+            if [[ "${PULL_REQUEST_STATE}" != "OPEN" ]]
+            then
               echo "::set-output name=pull_request::true"
             fi
           fi
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 5ac89b1287..50301bb217 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -90,10 +90,10 @@ jobs:
       - name: Set up all Homebrew taps
         run: |
           HOMEBREW_REPOSITORY="$(brew --repo)"
-          HOMEBREW_CORE_REPOSITORY="$HOMEBREW_REPOSITORY/Library/Taps/homebrew/homebrew-core"
-          git -C "$HOMEBREW_CORE_REPOSITORY" remote add homebrew_core https://github.com/Homebrew/homebrew-core
-          git -C "$HOMEBREW_CORE_REPOSITORY" fetch homebrew_core || git -C "$HOMEBREW_CORE_REPOSITORY" fetch homebrew_core
-          git -C "$HOMEBREW_CORE_REPOSITORY" checkout --force -B master homebrew_core/master
+          HOMEBREW_CORE_REPOSITORY="${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core"
+          git -C "${HOMEBREW_CORE_REPOSITORY}" remote add homebrew_core https://github.com/Homebrew/homebrew-core
+          git -C "${HOMEBREW_CORE_REPOSITORY}" fetch homebrew_core || git -C "${HOMEBREW_CORE_REPOSITORY}" fetch homebrew_core
+          git -C "${HOMEBREW_CORE_REPOSITORY}" checkout --force -B master homebrew_core/master
 
           brew tap homebrew/aliases
           brew tap homebrew/autoupdate
@@ -111,7 +111,7 @@ jobs:
           brew update-reset Library/Taps/homebrew/homebrew-bundle
 
           # brew style doesn't like world writable directories
-          sudo chmod -R g-w,o-w "$HOMEBREW_REPOSITORY/Library/Taps"
+          sudo chmod -R g-w,o-w "${HOMEBREW_REPOSITORY}/Library/Taps"
 
       - name: Run brew style on homebrew-core
         run: brew style --display-cop-names homebrew/core
@@ -178,11 +178,11 @@ jobs:
       - name: Deploy the Docker image to GitHub Packages and Docker Hub
         if: github.ref == 'refs/heads/master'
         run: |
-          echo ${{secrets.HOMEBREW_BREW_GITHUB_PACKAGES_TOKEN}} | \
+          echo ${{secrets.HOMEBREW_BREW_GITHUB_PACKAGES_TOKEN}} |
             docker login ghcr.io -u BrewTestBot --password-stdin
           docker tag brew "ghcr.io/homebrew/ubuntu16.04:master"
           docker push "ghcr.io/homebrew/ubuntu16.04:master"
-          echo ${{secrets.HOMEBREW_BREW_DOCKER_TOKEN}} | \
+          echo ${{secrets.HOMEBREW_BREW_DOCKER_TOKEN}} |
             docker login -u brewtestbot --password-stdin
           docker tag brew "homebrew/ubuntu16.04:master"
           docker push "homebrew/ubuntu16.04:master"
@@ -321,9 +321,10 @@ jobs:
         run: |
           # Retry multiple times when using BuildPulse to detect and submit
           # flakiness (because rspec-retry is disabled).
-          if [ -n "$HOMEBREW_BUILDPULSE_ACCESS_KEY_ID" ]; then
-            brew tests --online --coverage || \
-            brew tests --online --coverage || \
+          if [[ -n "${HOMEBREW_BUILDPULSE_ACCESS_KEY_ID}" ]]
+          then
+            brew tests --online --coverage ||
+            brew tests --online --coverage ||
             brew tests --online --coverage
           else
             brew tests --online --coverage
diff --git a/.github/workflows/update-man-completions.yml b/.github/workflows/update-man-completions.yml
index 71125d33c4..a5587eec1e 100644
--- a/.github/workflows/update-man-completions.yml
+++ b/.github/workflows/update-man-completions.yml
@@ -44,27 +44,31 @@ jobs:
           BRANCH=update-man-completions
           echo "::set-output name=branch::${BRANCH}"
 
-          if git ls-remote --exit-code --heads origin "$BRANCH"; then
-            git checkout "$BRANCH"
+          if git ls-remote --exit-code --heads origin "${BRANCH}"
+          then
+            git checkout "${BRANCH}"
             git reset --hard origin/master
           else
-            git checkout --no-track -B "$BRANCH" origin/master
+            git checkout --no-track -B "${BRANCH}" origin/master
           fi
 
-          if [ "${{github.event_name}}" != "push" ]; then
+          if [[ "${{github.event_name}}" != "push" ]]
+          then
             brew update-maintainers
           fi
 
-          if brew generate-man-completions --fail-if-not-changed; then
-            git add "$GITHUB_WORKSPACE/README.md" \
-                    "$GITHUB_WORKSPACE/docs/Manpage.md" \
-                    "$GITHUB_WORKSPACE/manpages/brew.1" \
-                    "$GITHUB_WORKSPACE/completions"
+          if brew generate-man-completions --fail-if-not-changed
+          then
+            git add "${GITHUB_WORKSPACE}/README.md" \
+                    "${GITHUB_WORKSPACE}/docs/Manpage.md" \
+                    "${GITHUB_WORKSPACE}/manpages/brew.1" \
+                    "${GITHUB_WORKSPACE}/completions"
             git commit -m "Update maintainers, manpage and completions." \
                        -m "Autogenerated by the [update-man-completions](https://github.com/Homebrew/brew/blob/HEAD/.github/workflows/update-man-completions.yml) workflow."
             echo "::set-output name=committed::true"
-            PULL_REQUEST_STATE=$(gh pr view --json=state | jq -r ".state")
-            if [ "$PULL_REQUEST_STATE" != "OPEN" ]; then
+            PULL_REQUEST_STATE="$(gh pr view --json=state | jq -r ".state")"
+            if [[ "${PULL_REQUEST_STATE}" != "OPEN" ]]
+            then
               echo "::set-output name=pull_request::true"
             fi
           fi
diff --git a/.github/workflows/vendor-gems.yml b/.github/workflows/vendor-gems.yml
index 0ffadcac95..d641b0e9de 100644
--- a/.github/workflows/vendor-gems.yml
+++ b/.github/workflows/vendor-gems.yml
@@ -51,7 +51,8 @@ jobs:
         run: |
           set -u
 
-          if [[ "${GEM_NAME}" == 'sorbet' ]]; then
+          if [[ "${GEM_NAME}" == 'sorbet' ]]
+          then
             brew vendor-gems --update sorbet,sorbet-runtime
           else
             brew vendor-gems
@@ -63,8 +64,10 @@ jobs:
         run: |
           set -u
 
-          if brew typecheck --update --fail-if-not-changed; then
-            if git add Library/Homebrew/sorbet; then
+          if brew typecheck --update --fail-if-not-changed
+          then
+            if git add Library/Homebrew/sorbet
+            then
               git commit -m "Update RBI files for ${GEM_NAME}."
             fi
 
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 20151d086d..9ebb6c4160 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -2,5 +2,5 @@
     "ruby.rubocop.executePath": "Library/Homebrew/shims/gems/",
     "files.trimTrailingWhitespace": true,
     "editor.tabSize": 2,
-    "files.insertFinalNewline": true,
+    "files.insertFinalNewline": true
 }
diff --git a/Dockerfile b/Dockerfile
index 99cecbe7db..701fc09bed 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -34,7 +34,7 @@ RUN apt-get update \
 
 USER linuxbrew
 COPY --chown=linuxbrew:linuxbrew . /home/linuxbrew/.linuxbrew/Homebrew
-ENV PATH=/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin:$PATH
+ENV PATH="/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin:${PATH}"
 WORKDIR /home/linuxbrew
 
 RUN mkdir -p \
diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index 13d3c3a21c..b0bd5dbe33 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -17,10 +17,11 @@ esac
 # same file under the native architecture
 # These variables are set from the user environment.
 # shellcheck disable=SC2154
-if [[ "${HOMEBREW_CHANGE_ARCH_TO_ARM}" = "1" ]] && \
-   [[ "${HOMEBREW_MACOS}" = "1" ]] && \
-   [[ "$(sysctl -n hw.optional.arm64 2>/dev/null)" = "1" ]] && \
-   [[ "$(sysctl -n sysctl.proc_translated 2>/dev/null)" = "1" ]]; then
+if [[ "${HOMEBREW_CHANGE_ARCH_TO_ARM}" == "1" ]] &&
+   [[ "${HOMEBREW_MACOS}" == "1" ]] &&
+   [[ "$(sysctl -n hw.optional.arm64 2>/dev/null)" == "1" ]] &&
+   [[ "$(sysctl -n sysctl.proc_translated 2>/dev/null)" == "1" ]]
+then
   exec arch -arm64e "${HOMEBREW_BREW_FILE}" "$@"
 fi
 
@@ -55,15 +56,15 @@ HOMEBREW_TEMP="${HOMEBREW_TEMP:-${HOMEBREW_DEFAULT_TEMP}}"
 # HOMEBREW_LIBRARY set by bin/brew
 # shellcheck disable=SC2249,SC2154
 case "$*" in
-  --cellar)            echo "${HOMEBREW_CELLAR}"; exit 0 ;;
-  --repository|--repo) echo "${HOMEBREW_REPOSITORY}"; exit 0 ;;
-  --caskroom)          echo "${HOMEBREW_PREFIX}/Caskroom"; exit 0 ;;
-  --cache)             echo "${HOMEBREW_CACHE}"; exit 0 ;;
-  shellenv)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/shellenv.sh"; homebrew-shellenv; exit 0 ;;
-  formulae)            source "${HOMEBREW_LIBRARY}/Homebrew/cmd/formulae.sh"; homebrew-formulae; exit 0 ;;
-  casks)               source "${HOMEBREW_LIBRARY}/Homebrew/cmd/casks.sh"; homebrew-casks; exit 0 ;;
+  --cellar)              echo "${HOMEBREW_CELLAR}"; exit 0 ;;
+  --repository | --repo) echo "${HOMEBREW_REPOSITORY}"; exit 0 ;;
+  --caskroom)            echo "${HOMEBREW_PREFIX}/Caskroom"; exit 0 ;;
+  --cache)               echo "${HOMEBREW_CACHE}"; exit 0 ;;
+  shellenv)              source "${HOMEBREW_LIBRARY}/Homebrew/cmd/shellenv.sh"; homebrew-shellenv; exit 0 ;;
+  formulae)              source "${HOMEBREW_LIBRARY}/Homebrew/cmd/formulae.sh"; homebrew-formulae; exit 0 ;;
+  casks)                 source "${HOMEBREW_LIBRARY}/Homebrew/cmd/casks.sh"; homebrew-casks; exit 0 ;;
   # falls back to cmd/prefix.rb on a non-zero return
-  --prefix*)           source "${HOMEBREW_LIBRARY}/Homebrew/prefix.sh"; homebrew-prefix "$@" && exit 0 ;;
+  --prefix*)             source "${HOMEBREW_LIBRARY}/Homebrew/prefix.sh"; homebrew-prefix "$@" && exit 0 ;;
 esac
 
 #####
@@ -144,16 +145,16 @@ numeric() {
 }
 
 check-run-command-as-root() {
-  [[ "$(id -u)" = 0 ]] || return
+  [[ "$(id -u)" == 0 ]] || return
 
   # Allow Azure Pipelines/GitHub Actions/Docker/Concourse/Kubernetes to do everything as root (as it's normal there)
   [[ -f /proc/1/cgroup ]] && grep -E "azpl_job|actions_job|docker|garden|kubepods" -q /proc/1/cgroup && return
 
   # Homebrew Services may need `sudo` for system-wide daemons.
-  [[ "${HOMEBREW_COMMAND}" = "services" ]] && return
+  [[ "${HOMEBREW_COMMAND}" == "services" ]] && return
 
   # It's fine to run this as root as it's not changing anything.
-  [[ "${HOMEBREW_COMMAND}" = "--prefix" ]] && return
+  [[ "${HOMEBREW_COMMAND}" == "--prefix" ]] && return
 
   odie <<EOS
 Running Homebrew as root is extremely dangerous and no longer supported.
@@ -165,7 +166,7 @@ EOS
 check-prefix-is-not-tmpdir() {
   [[ -z "${HOMEBREW_MACOS}" ]] && return
 
-  if [[ "${HOMEBREW_PREFIX}" = "${HOMEBREW_TEMP}"* ]]
+  if [[ "${HOMEBREW_PREFIX}" == "${HOMEBREW_TEMP}"* ]]
   then
     odie <<EOS
 Your HOMEBREW_PREFIX is in the Homebrew temporary directory, which Homebrew
@@ -195,10 +196,13 @@ update-preinstall() {
   # If we've checked for updates, we don't need to check again.
   export HOMEBREW_AUTO_UPDATE_CHECKED="1"
 
-  if [[ "${HOMEBREW_COMMAND}" = "install" || "${HOMEBREW_COMMAND}" = "upgrade" ||
-        "${HOMEBREW_COMMAND}" = "bump-formula-pr" || "${HOMEBREW_COMMAND}" = "bump-cask-pr" ||
-        "${HOMEBREW_COMMAND}" = "bundle" || "${HOMEBREW_COMMAND}" = "release" ||
-        "${HOMEBREW_COMMAND}" = "tap" && ${HOMEBREW_ARG_COUNT} -gt 1 ]]
+  if [[ "${HOMEBREW_COMMAND}" == "install" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "upgrade" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "bump-formula-pr" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "bump-cask-pr" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "bundle" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "release" ]] ||
+     [[ "${HOMEBREW_COMMAND}" == "tap" && "${HOMEBREW_ARG_COUNT}" -gt 1 ]]
   then
     export HOMEBREW_AUTO_UPDATING="1"
 
@@ -210,8 +214,8 @@ update-preinstall() {
     # Skip auto-update if the repository has been updated in the
     # last $HOMEBREW_AUTO_UPDATE_SECS.
     repo_fetch_head="${HOMEBREW_REPOSITORY}/.git/FETCH_HEAD"
-    if [[ -f "${repo_fetch_head}" &&
-          -n "$(find "${repo_fetch_head}" -type f -mtime -"${HOMEBREW_AUTO_UPDATE_SECS}"s 2>/dev/null)" ]]
+    if [[ -f "${repo_fetch_head}" ]] &&
+       [[ -n "$(find "${repo_fetch_head}" -type f -mtime -"${HOMEBREW_AUTO_UPDATE_SECS}"s 2>/dev/null)" ]]
     then
       return
     fi
@@ -244,7 +248,8 @@ update-preinstall() {
 # Colorize output on GitHub Actions.
 # This is set by the user environment.
 # shellcheck disable=SC2154
-if [[ -n "${GITHUB_ACTIONS}" ]]; then
+if [[ -n "${GITHUB_ACTIONS}" ]]
+then
   export HOMEBREW_COLOR="1"
 fi
 
@@ -261,13 +266,13 @@ else
     export LC_ALL=C
   elif [[ "$(locale charmap)" != "UTF-8" ]]
   then
-    locales=$(locale -a)
+    locales="$(locale -a)"
     c_utf_regex='\bC\.(utf8|UTF-8)\b'
     en_us_regex='\ben_US\.(utf8|UTF-8)\b'
     utf_regex='\b[a-z][a-z]_[A-Z][A-Z]\.(utf8|UTF-8)\b'
     if [[ ${locales} =~ ${c_utf_regex} || ${locales} =~ ${en_us_regex} || ${locales} =~ ${utf_regex} ]]
     then
-      export LC_ALL=${BASH_REMATCH[0]}
+      export LC_ALL="${BASH_REMATCH[0]}"
     else
       export LC_ALL=C
     fi
@@ -278,7 +283,7 @@ fi
 ##### odie as quickly as possible.
 #####
 
-if [[ "${HOMEBREW_PREFIX}" = "/" || "${HOMEBREW_PREFIX}" = "/usr" ]]
+if [[ "${HOMEBREW_PREFIX}" == "/" || "${HOMEBREW_PREFIX}" == "/usr" ]]
 then
   # it may work, but I only see pain this route and don't want to support it
   odie "Cowardly refusing to continue at this prefix: ${HOMEBREW_PREFIX}"
@@ -296,17 +301,16 @@ fi
 #####
 
 # USER isn't always set so provide a fall back for `brew` and subprocesses.
-export USER=${USER:-$(id -un)}
+export USER="${USER:-$(id -un)}"
 
 # A depth of 1 means this command was directly invoked by a user.
 # Higher depths mean this command was invoked by another Homebrew command.
-export HOMEBREW_COMMAND_DEPTH=$((HOMEBREW_COMMAND_DEPTH + 1))
+export HOMEBREW_COMMAND_DEPTH="$((HOMEBREW_COMMAND_DEPTH + 1))"
 
 # This is set by the user environment.
 # shellcheck disable=SC2154
-if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" &&
-      -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]] &&
-         "${HOMEBREW_PREFIX}/opt/curl/bin/curl" --version >/dev/null
+if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" && -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]] &&
+   "${HOMEBREW_PREFIX}/opt/curl/bin/curl" --version >/dev/null
 then
   HOMEBREW_CURL="${HOMEBREW_PREFIX}/opt/curl/bin/curl"
 elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_CURL_PATH}" ]]
@@ -318,9 +322,8 @@ fi
 
 # This is set by the user environment.
 # shellcheck disable=SC2154
-if [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" &&
-      -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]] &&
-         "${HOMEBREW_PREFIX}/opt/git/bin/git" --version >/dev/null
+if [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" && -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]] &&
+   "${HOMEBREW_PREFIX}/opt/git/bin/git" --version >/dev/null
 then
   HOMEBREW_GIT="${HOMEBREW_PREFIX}/opt/git/bin/git"
 elif [[ -n "${HOMEBREW_DEVELOPER}" && -x "${HOMEBREW_GIT_PATH}" ]]
@@ -344,7 +347,11 @@ HOMEBREW_CORE_REPOSITORY="${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core"
 HOMEBREW_CASK_REPOSITORY="${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-cask"
 
 case "$*" in
-  --version|-v) source "${HOMEBREW_LIBRARY}/Homebrew/cmd/--version.sh"; homebrew-version; exit 0 ;;
+  --version | -v)
+    source "${HOMEBREW_LIBRARY}/Homebrew/cmd/--version.sh"
+    homebrew-version
+    exit 0
+    ;;
 esac
 
 # shellcheck disable=SC2154
@@ -357,7 +364,7 @@ if [[ -n "${HOMEBREW_MACOS}" ]]
 then
   HOMEBREW_PRODUCT="Homebrew"
   HOMEBREW_SYSTEM="Macintosh"
-  [[ "${HOMEBREW_PROCESSOR}" = "x86_64" ]] && HOMEBREW_PROCESSOR="Intel"
+  [[ "${HOMEBREW_PROCESSOR}" == "x86_64" ]] && HOMEBREW_PROCESSOR="Intel"
   HOMEBREW_MACOS_VERSION="$(/usr/bin/sw_vers -productVersion)"
   # Don't change this from Mac OS X to match what macOS itself does in Safari on 10.12
   HOMEBREW_OS_USER_AGENT_VERSION="Mac OS X ${HOMEBREW_MACOS_VERSION}"
@@ -423,17 +430,19 @@ else
   curl_version_output="$(${HOMEBREW_CURL} --version 2>/dev/null)"
   curl_name_and_version="${curl_version_output%% (*}"
   # shellcheck disable=SC2248
-  if [[ $(numeric "${curl_name_and_version##* }") -lt $(numeric "${HOMEBREW_MINIMUM_CURL_VERSION}") ]]
+  if [[ "$(numeric "${curl_name_and_version##* }")" -lt "$(numeric "${HOMEBREW_MINIMUM_CURL_VERSION}")" ]]
   then
-      message="Please update your system curl.
+    message="Please update your system curl.
 Minimum required version: ${HOMEBREW_MINIMUM_CURL_VERSION}
 Your curl version: ${curl_name_and_version##* }
 Your curl executable: $(type -p ${HOMEBREW_CURL})"
 
-    if [[ -z ${HOMEBREW_CURL_PATH} || -z ${HOMEBREW_DEVELOPER} ]]; then
+    if [[ -z ${HOMEBREW_CURL_PATH} || -z ${HOMEBREW_DEVELOPER} ]]
+    then
       HOMEBREW_SYSTEM_CURL_TOO_OLD=1
       HOMEBREW_FORCE_BREWED_CURL=1
-      if [[ -z ${HOMEBREW_CURL_WARNING} ]]; then
+      if [[ -z ${HOMEBREW_CURL_WARNING} ]]
+      then
         onoe "${message}"
         HOMEBREW_CURL_WARNING=1
       fi
@@ -448,17 +457,19 @@ Your curl executable: $(type -p ${HOMEBREW_CURL})"
   git_version_output="$(${HOMEBREW_GIT} --version 2>/dev/null)"
   # $extra is intentionally discarded.
   # shellcheck disable=SC2034
-  IFS=. read -r major minor micro build extra <<< "${git_version_output##* }"
+  IFS='.' read -r major minor micro build extra <<<"${git_version_output##* }"
   # shellcheck disable=SC2248
-  if [[ $(numeric "${major}.${minor}.${micro}.${build}") -lt $(numeric "${HOMEBREW_MINIMUM_GIT_VERSION}") ]]
+  if [[ "$(numeric "${major}.${minor}.${micro}.${build}")" -lt "$(numeric "${HOMEBREW_MINIMUM_GIT_VERSION}")" ]]
   then
     message="Please update your system Git.
 Minimum required version: ${HOMEBREW_MINIMUM_GIT_VERSION}
 Your Git version: ${major}.${minor}.${micro}.${build}
 Your Git executable: $(unset git && type -p ${HOMEBREW_GIT})"
-    if [[ -z ${HOMEBREW_GIT_PATH} || -z ${HOMEBREW_DEVELOPER} ]]; then
+    if [[ -z ${HOMEBREW_GIT_PATH} || -z ${HOMEBREW_DEVELOPER} ]]
+    then
       HOMEBREW_FORCE_BREWED_GIT="1"
-      if [[ -z ${HOMEBREW_GIT_WARNING} ]]; then
+      if [[ -z ${HOMEBREW_GIT_WARNING} ]]
+      then
         onoe "${message}"
         HOMEBREW_GIT_WARNING=1
       fi
@@ -471,7 +482,7 @@ Your Git executable: $(unset git && type -p ${HOMEBREW_GIT})"
   unset HOMEBREW_MACOS_SYSTEM_RUBY_NEW_ENOUGH
 
   HOMEBREW_CORE_REPOSITORY_ORIGIN="$("${HOMEBREW_GIT}" -C "${HOMEBREW_CORE_REPOSITORY}" remote get-url origin)"
-  if [[ "${HOMEBREW_CORE_REPOSITORY_ORIGIN}" = "https://github.com/Homebrew/homebrew-core" ]]
+  if [[ "${HOMEBREW_CORE_REPOSITORY_ORIGIN}" == "https://github.com/Homebrew/homebrew-core" ]]
   then
     # If the remote origin has been set to Homebrew/homebrew-core by the install script,
     # then we are in the case of a new installation of brew, using Homebrew/homebrew-core as a Linux core repository.
@@ -490,12 +501,15 @@ fi
 # That will be when macOS 12 is the minimum required version.
 # HOMEBREW_BOTTLE_DOMAIN is set from the user environment
 # shellcheck disable=SC2154
-if [[ -n "${HOMEBREW_BOTTLE_DEFAULT_DOMAIN}" && "${HOMEBREW_BOTTLE_DOMAIN}" = "${HOMEBREW_BOTTLE_DEFAULT_DOMAIN}" ]]
+if [[ -n "${HOMEBREW_BOTTLE_DEFAULT_DOMAIN}" ]] &&
+   [[ "${HOMEBREW_BOTTLE_DOMAIN}" == "${HOMEBREW_BOTTLE_DEFAULT_DOMAIN}" ]]
 then
   unset HOMEBREW_BOTTLE_DOMAIN
 fi
 
-if [[ -n "${HOMEBREW_MACOS}" || -n "${HOMEBREW_FORCE_HOMEBREW_ON_LINUX}" || -n "${HOMEBREW_FORCE_HOMEBREW_CORE_REPO_ON_LINUX}" ]]
+if [[ -n "${HOMEBREW_MACOS}" ]] ||
+   [[ -n "${HOMEBREW_FORCE_HOMEBREW_ON_LINUX}" ]] ||
+   [[ -n "${HOMEBREW_FORCE_HOMEBREW_CORE_REPO_ON_LINUX}" ]]
 then
   HOMEBREW_BOTTLE_DEFAULT_DOMAIN="https://ghcr.io/v2/homebrew/core"
 else
@@ -535,8 +549,8 @@ export HOMEBREW_MACOS_SYSTEM_RUBY_NEW_ENOUGH
 
 if [[ -n "${HOMEBREW_MACOS}" && -x "/usr/bin/xcode-select" ]]
 then
-  XCODE_SELECT_PATH=$('/usr/bin/xcode-select' --print-path 2>/dev/null)
-  if [[ "${XCODE_SELECT_PATH}" = "/" ]]
+  XCODE_SELECT_PATH="$('/usr/bin/xcode-select' --print-path 2>/dev/null)"
+  if [[ "${XCODE_SELECT_PATH}" == "/" ]]
   then
     odie <<EOS
 Your xcode-select path is currently set to '/'.
@@ -555,7 +569,7 @@ EOS
     XCRUN_OUTPUT="$(/usr/bin/xcrun clang 2>&1)"
     XCRUN_STATUS="$?"
 
-    if [[ "${XCRUN_STATUS}" -ne 0 && "${XCRUN_OUTPUT}" = *license* ]]
+    if [[ "${XCRUN_STATUS}" -ne 0 && "${XCRUN_OUTPUT}" == *license* ]]
     then
       odie <<EOS
 You have not agreed to the Xcode license. Please resolve this by running:
@@ -565,7 +579,7 @@ EOS
   fi
 fi
 
-if [[ "$1" = -v ]]
+if [[ "$1" == "-v" ]]
 then
   # Shift the -v to the end of the parameter list
   shift
@@ -574,9 +588,9 @@ fi
 
 for arg in "$@"
 do
-  [[ ${arg} = "--" ]] && break
+  [[ "${arg}" == "--" ]] && break
 
-  if [[ ${arg} = "--help" || ${arg} = "-h" || ${arg} = "--usage" || ${arg} = "-?" ]]
+  if [[ "${arg}" == "--help" || "${arg}" == "-h" || "${arg}" == "--usage" || "${arg}" == "-?" ]]
   then
     export HOMEBREW_HELP="1"
     break
@@ -611,7 +625,7 @@ if [[ -z "${HOMEBREW_DEVELOPER}" ]]
 then
   export HOMEBREW_GIT_CONFIG_FILE="${HOMEBREW_REPOSITORY}/.git/config"
   HOMEBREW_GIT_CONFIG_DEVELOPERMODE="$(git config --file="${HOMEBREW_GIT_CONFIG_FILE}" --get homebrew.devcmdrun 2>/dev/null)"
-  if [[ "${HOMEBREW_GIT_CONFIG_DEVELOPERMODE}" = "true" ]]
+  if [[ "${HOMEBREW_GIT_CONFIG_DEVELOPERMODE}" == "true" ]]
   then
     export HOMEBREW_DEV_CMD_RUN="1"
   fi
@@ -635,7 +649,9 @@ then
 fi
 export HOMEBREW_BREW_GIT_REMOTE
 
-if [[ -n "${HOMEBREW_MACOS}" ]] || [[ -n "${HOMEBREW_FORCE_HOMEBREW_ON_LINUX}" ]]  || [[ -n "${HOMEBREW_FORCE_HOMEBREW_CORE_REPO_ON_LINUX}" ]]
+if [[ -n "${HOMEBREW_MACOS}" ]] ||
+   [[ -n "${HOMEBREW_FORCE_HOMEBREW_ON_LINUX}" ]] ||
+   [[ -n "${HOMEBREW_FORCE_HOMEBREW_CORE_REPO_ON_LINUX}" ]]
 then
   HOMEBREW_CORE_DEFAULT_GIT_REMOTE="https://github.com/Homebrew/homebrew-core"
 else
@@ -676,9 +692,9 @@ check-run-command-as-root
 check-prefix-is-not-tmpdir
 
 # shellcheck disable=SC2250
-if [[ "${HOMEBREW_PREFIX}" = "/usr/local" &&
-      "${HOMEBREW_PREFIX}" != "${HOMEBREW_REPOSITORY}" &&
-      "${HOMEBREW_CELLAR}" = "${HOMEBREW_REPOSITORY}/Cellar" ]]
+if [[ "${HOMEBREW_PREFIX}" == "/usr/local" ]] &&
+   [[ "${HOMEBREW_PREFIX}" != "${HOMEBREW_REPOSITORY}" ]] &&
+   [[ "${HOMEBREW_CELLAR}" == "${HOMEBREW_REPOSITORY}/Cellar" ]]
 then
   cat >&2 <<EOS
 Warning: your HOMEBREW_PREFIX is set to /usr/local but HOMEBREW_CELLAR is set
@@ -702,7 +718,13 @@ then
   # Shellcheck can't follow this dynamic `source`.
   # shellcheck disable=SC1090
   source "${HOMEBREW_BASH_COMMAND}"
-  { update-preinstall "$@"; "homebrew-${HOMEBREW_COMMAND}" "$@"; exit $?; }
+
+  {
+    update-preinstall "$@"
+    "homebrew-${HOMEBREW_COMMAND}" "$@"
+    exit $?
+  }
+
 else
   source "${HOMEBREW_LIBRARY}/Homebrew/utils/ruby.sh"
   setup-ruby-path
@@ -711,5 +733,9 @@ else
   [[ "${HOMEBREW_ARG_COUNT}" -gt 0 ]] && set -- "${HOMEBREW_COMMAND}" "$@"
   # HOMEBREW_RUBY_PATH set by utils/ruby.sh
   # shellcheck disable=SC2154
-  { update-preinstall "$@"; exec "${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_WARNINGS}" "${RUBY_DISABLE_OPTIONS}" "${HOMEBREW_LIBRARY}/Homebrew/brew.rb" "$@"; }
+  {
+    update-preinstall "$@"
+    exec "${HOMEBREW_RUBY_PATH}" "${HOMEBREW_RUBY_WARNINGS}" "${RUBY_DISABLE_OPTIONS}" \
+         "${HOMEBREW_LIBRARY}/Homebrew/brew.rb" "$@"
+  }
 fi
diff --git a/Library/Homebrew/cask/utils/rmdir.sh b/Library/Homebrew/cask/utils/rmdir.sh
index b1a271d1b1..30fc3b150d 100755
--- a/Library/Homebrew/cask/utils/rmdir.sh
+++ b/Library/Homebrew/cask/utils/rmdir.sh
@@ -4,34 +4,41 @@ set -euo pipefail
 
 # Try removing as many empty directories as possible with a single
 # `rmdir` call to avoid or at least speed up the loop below.
-if /bin/rmdir -- "${@}" &>/dev/null; then
+if /bin/rmdir -- "${@}" &>/dev/null
+then
   exit
 fi
 
-for path in "${@}"; do
+for path in "${@}"
+do
   symlink=true
   [[ -L "${path}" ]] || symlink=false
 
   directory=false
-  if [[ -d "${path}"  ]]; then
+  if [[ -d "${path}" ]]
+  then
     directory=true
 
-    if [[ -e "${path}/.DS_Store" ]]; then
+    if [[ -e "${path}/.DS_Store" ]]
+    then
       /bin/rm -- "${path}/.DS_Store"
     fi
 
     # Some packages leave broken symlinks around; we clean them out before
     # attempting to `rmdir` to prevent extra cruft from accumulating.
     /usr/bin/find -f "${path}" -- -mindepth 1 -maxdepth 1 -type l ! -exec /bin/test -e {} \; -delete
-  elif ! ${symlink} && [[ ! -e "${path}" ]]; then
+  elif ! ${symlink} && [[ ! -e "${path}" ]]
+  then
     # Skip paths that don't exists and aren't a broken symlink.
     continue
   fi
 
-  if ${symlink}; then
+  if ${symlink}
+  then
     # Delete directory symlink.
     /bin/rm -- "${path}"
-  elif ${directory}; then
+  elif ${directory}
+  then
     # Delete directory if empty.
     /usr/bin/find -f "${path}" -- -maxdepth 0 -type d -empty -exec /bin/rmdir -- {} \;
   else
diff --git a/Library/Homebrew/cmd/--version.sh b/Library/Homebrew/cmd/--version.sh
index bcd2d21264..caf3ea6257 100644
--- a/Library/Homebrew/cmd/--version.sh
+++ b/Library/Homebrew/cmd/--version.sh
@@ -6,20 +6,22 @@
 # shellcheck disable=SC2154
 version_string() {
   local repo="$1"
-  if ! [ -d "${repo}" ]; then
+  if ! [[ -d "${repo}" ]]
+  then
     echo "N/A"
     return
   fi
 
   local pretty_revision
   pretty_revision="$(git -C "${repo}" rev-parse --short --verify --quiet HEAD)"
-  if [ -z "${pretty_revision}" ]; then
+  if [[ -z "${pretty_revision}" ]]
+  then
     echo "(no Git repository)"
     return
   fi
 
   local git_last_commit_date
-  git_last_commit_date=$(git -C "${repo}" show -s --format='%cd' --date=short HEAD)
+  git_last_commit_date="$(git -C "${repo}" show -s --format='%cd' --date=short HEAD)"
   echo "(git revision ${pretty_revision}; last commit ${git_last_commit_date})"
 }
 
@@ -27,7 +29,8 @@ homebrew-version() {
   echo "Homebrew ${HOMEBREW_VERSION}"
   echo "Homebrew/homebrew-core $(version_string "${HOMEBREW_CORE_REPOSITORY}")"
 
-  if [ -d "${HOMEBREW_CASK_REPOSITORY}" ]; then
+  if [[ -d "${HOMEBREW_CASK_REPOSITORY}" ]]
+  then
     echo "Homebrew/homebrew-cask $(version_string "${HOMEBREW_CASK_REPOSITORY}")"
   fi
 }
diff --git a/Library/Homebrew/cmd/shellenv.sh b/Library/Homebrew/cmd/shellenv.sh
index 4ed9ecb6e8..89b3ae8e06 100644
--- a/Library/Homebrew/cmd/shellenv.sh
+++ b/Library/Homebrew/cmd/shellenv.sh
@@ -4,14 +4,14 @@
 #:
 #:  The variables `HOMEBREW_PREFIX`, `HOMEBREW_CELLAR` and `HOMEBREW_REPOSITORY` are also exported to avoid querying them multiple times.
 #:  The variable `HOMEBREW_SHELLENV_PREFIX` will be exported to avoid adding duplicate entries to the environment variables.
-#:  Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval $(brew shellenv)`
+#:  Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval "$(brew shellenv)"`
 
 # HOMEBREW_CELLAR and HOMEBREW_PREFIX are set by extend/ENV/super.rb
 # HOMEBREW_REPOSITORY is set by bin/brew
 # shellcheck disable=SC2154
 homebrew-shellenv() {
-  [[ "${HOMEBREW_SHELLENV_PREFIX}" == "${HOMEBREW_PREFIX}" &&
-     "$(PATH="${HOMEBREW_PATH}" command -v brew)" == "${HOMEBREW_PREFIX}/bin/brew" ]] && return
+  [[ "${HOMEBREW_SHELLENV_PREFIX}" == "${HOMEBREW_PREFIX}" ]] &&
+  [[ "$(PATH="${HOMEBREW_PATH}" command -v brew)" == "${HOMEBREW_PREFIX}/bin/brew" ]] && return
 
   case "$(/bin/ps -p "${PPID}" -c -o comm=)" in
     fish | -fish)
diff --git a/Library/Homebrew/cmd/update-reset.sh b/Library/Homebrew/cmd/update-reset.sh
index 008d6d691f..fb7a99c193 100644
--- a/Library/Homebrew/cmd/update-reset.sh
+++ b/Library/Homebrew/cmd/update-reset.sh
@@ -11,10 +11,10 @@ homebrew-update-reset() {
   for option in "$@"
   do
     case "${option}" in
-      -\?|-h|--help|--usage)          brew help update-reset; exit $? ;;
-      --debug)                        HOMEBREW_DEBUG=1 ;;
+      -\? | -h | --help | --usage) brew help update-reset; exit $? ;;
+      --debug)                     HOMEBREW_DEBUG=1 ;;
       -*)
-        [[ "${option}" = *d* ]] && HOMEBREW_DEBUG=1
+        [[ "${option}" == *d* ]] && HOMEBREW_DEBUG=1
         ;;
       *)
         REPOS+=("${option}")
diff --git a/Library/Homebrew/cmd/update.sh b/Library/Homebrew/cmd/update.sh
index a062c8edb5..595c8042f5 100644
--- a/Library/Homebrew/cmd/update.sh
+++ b/Library/Homebrew/cmd/update.sh
@@ -77,7 +77,7 @@ repo_var() {
   local repo_var
 
   repo_var="$1"
-  if [[ "${repo_var}" = "${HOMEBREW_REPOSITORY}" ]]
+  if [[ "${repo_var}" == "${HOMEBREW_REPOSITORY}" ]]
   then
     repo_var=""
   else
@@ -193,16 +193,18 @@ merge_or_rebase() {
 
   trap reset_on_interrupt SIGINT
 
-  if [[ "${DIR}" = "${HOMEBREW_REPOSITORY}" && -n "${HOMEBREW_UPDATE_TO_TAG}" ]]
+  if [[ "${DIR}" == "${HOMEBREW_REPOSITORY}" && -n "${HOMEBREW_UPDATE_TO_TAG}" ]]
   then
-    UPSTREAM_TAG="$(git tag --list |
-                    sort --field-separator=. --key=1,1nr -k 2,2nr -k 3,3nr |
-                    grep --max-count=1 '^[0-9]*\.[0-9]*\.[0-9]*$')"
+    UPSTREAM_TAG="$(
+      git tag --list |
+        sort --field-separator=. --key=1,1nr -k 2,2nr -k 3,3nr |
+        grep --max-count=1 '^[0-9]*\.[0-9]*\.[0-9]*$'
+    )"
   else
     UPSTREAM_TAG=""
   fi
 
-  if [ -n "${UPSTREAM_TAG}" ]
+  if [[ -n "${UPSTREAM_TAG}" ]]
   then
     REMOTE_REF="refs/tags/${UPSTREAM_TAG}"
     UPSTREAM_BRANCH="stable"
@@ -288,8 +290,8 @@ EOS
 
   if [[ -n "${HOMEBREW_NO_UPDATE_CLEANUP}" ]]
   then
-    if [[ "${INITIAL_BRANCH}" != "${UPSTREAM_BRANCH}" && -n "${INITIAL_BRANCH}" &&
-          ! "${INITIAL_BRANCH}" =~ ^v[0-9]+\.[0-9]+\.[0-9]|stable$ ]]
+    if [[ "${INITIAL_BRANCH}" != "${UPSTREAM_BRANCH}" && -n "${INITIAL_BRANCH}" ]] &&
+       [[ ! "${INITIAL_BRANCH}" =~ ^v[0-9]+\.[0-9]+\.[0-9]|stable$ ]]
     then
       git checkout "${INITIAL_BRANCH}" "${QUIET_ARGS[@]}"
     fi
@@ -310,7 +312,7 @@ homebrew-update() {
   for option in "$@"
   do
     case "${option}" in
-      -\?|-h|--help|--usage)          brew help update; exit $? ;;
+      -\? | -h | --help | --usage)    brew help update; exit $? ;;
       --verbose)                      HOMEBREW_VERBOSE=1 ;;
       --debug)                        HOMEBREW_DEBUG=1 ;;
       --quiet)                        HOMEBREW_QUIET=1 ;;
@@ -320,10 +322,10 @@ homebrew-update() {
       --preinstall)                   export HOMEBREW_UPDATE_PREINSTALL=1 ;;
       --*)                            ;;
       -*)
-        [[ "${option}" = *v* ]] && HOMEBREW_VERBOSE=1
-        [[ "${option}" = *q* ]] && HOMEBREW_QUIET=1
-        [[ "${option}" = *d* ]] && HOMEBREW_DEBUG=1
-        [[ "${option}" = *f* ]] && HOMEBREW_UPDATE_FORCE=1
+        [[ "${option}" == *v* ]] && HOMEBREW_VERBOSE=1
+        [[ "${option}" == *q* ]] && HOMEBREW_QUIET=1
+        [[ "${option}" == *d* ]] && HOMEBREW_DEBUG=1
+        [[ "${option}" == *f* ]] && HOMEBREW_UPDATE_FORCE=1
         ;;
       *)
         odie <<EOS
@@ -371,8 +373,7 @@ EOS
   fi
 
   # we may want to use a Homebrew curl
-  if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" &&
-      ! -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]]
+  if [[ -n "${HOMEBREW_FORCE_BREWED_CURL}" && ! -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]]
   then
     # we cannot install a Homebrew cURL if homebrew/core is unavailable.
     if [[ ! -d "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]] || ! brew install curl
@@ -382,8 +383,7 @@ EOS
   fi
 
   if ! git --version &>/dev/null ||
-     [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" &&
-      ! -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]]
+     [[ -n "${HOMEBREW_FORCE_BREWED_GIT}" && ! -x "${HOMEBREW_PREFIX}/opt/git/bin/git" ]]
   then
     # we cannot install a Homebrew Git if homebrew/core is unavailable.
     if [[ ! -d "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]] || ! brew install git
@@ -394,7 +394,7 @@ EOS
 
   [[ -f "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core/.git/shallow" ]] && HOMEBREW_CORE_SHALLOW=1
   [[ -f "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-cask/.git/shallow" ]] && HOMEBREW_CASK_SHALLOW=1
-  if [[ -n ${HOMEBREW_CORE_SHALLOW} && -n ${HOMEBREW_CASK_SHALLOW} ]]
+  if [[ -n "${HOMEBREW_CORE_SHALLOW}" && -n "${HOMEBREW_CASK_SHALLOW}" ]]
   then
     SHALLOW_COMMAND_PHRASE="These commands"
     SHALLOW_REPO_PHRASE="repositories"
@@ -403,7 +403,7 @@ EOS
     SHALLOW_REPO_PHRASE="repository"
   fi
 
-  if [[ -n ${HOMEBREW_CORE_SHALLOW} || -n ${HOMEBREW_CASK_SHALLOW} ]]
+  if [[ -n "${HOMEBREW_CORE_SHALLOW}" || -n "${HOMEBREW_CASK_SHALLOW}" ]]
   then
     odie <<EOS
 ${HOMEBREW_CORE_SHALLOW:+
@@ -480,9 +480,8 @@ EOS
   safe_cd "${HOMEBREW_REPOSITORY}"
 
   # if an older system had a newer curl installed, change each repo's remote URL from GIT to HTTPS
-  if [[ -n "${HOMEBREW_SYSTEM_CURL_TOO_OLD}" &&
-        -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" &&
-        "$(git config remote.origin.url)" =~ ^git:// ]]
+  if [[ -n "${HOMEBREW_SYSTEM_CURL_TOO_OLD}" && -x "${HOMEBREW_PREFIX}/opt/curl/bin/curl" ]] &&
+     [[ "$(git config remote.origin.url)" =~ ^git:// ]]
   then
     git config remote.origin.url "${HOMEBREW_BREW_GIT_REMOTE}"
     git config -f "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core/.git/config" remote.origin.url "${HOMEBREW_CORE_GIT_REMOTE}"
@@ -498,8 +497,9 @@ EOS
 
   for DIR in "${HOMEBREW_REPOSITORY}" "${HOMEBREW_LIBRARY}"/Taps/*/*
   do
-    if [[ -n "${HOMEBREW_INSTALL_FROM_API}" ]] && [[ -n "${HOMEBREW_UPDATE_PREINSTALL}" ]] &&
-       [[ "${DIR}" = "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]]
+    if [[ -n "${HOMEBREW_INSTALL_FROM_API}" ]] &&
+       [[ -n "${HOMEBREW_UPDATE_PREINSTALL}" ]] &&
+       [[ "${DIR}" == "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]]
     then
       continue
     fi
@@ -518,15 +518,15 @@ EOS
     declare PREFETCH_REVISION"${TAP_VAR}"="$(git rev-parse -q --verify refs/remotes/origin/"${UPSTREAM_BRANCH_DIR}")"
 
     # Force a full update if we don't have any tags.
-    if [[ "${DIR}" = "${HOMEBREW_REPOSITORY}" && -z "$(git tag --list)" ]]
+    if [[ "${DIR}" == "${HOMEBREW_REPOSITORY}" && -z "$(git tag --list)" ]]
     then
       HOMEBREW_UPDATE_FORCE=1
     fi
 
     if [[ -z "${HOMEBREW_UPDATE_FORCE}" ]]
     then
-      [[ -n "${SKIP_FETCH_BREW_REPOSITORY}" && "${DIR}" = "${HOMEBREW_REPOSITORY}" ]] && continue
-      [[ -n "${SKIP_FETCH_CORE_REPOSITORY}" && "${DIR}" = "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]] && continue
+      [[ -n "${SKIP_FETCH_BREW_REPOSITORY}" && "${DIR}" == "${HOMEBREW_REPOSITORY}" ]] && continue
+      [[ -n "${SKIP_FETCH_CORE_REPOSITORY}" && "${DIR}" == "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ]] && continue
     fi
 
     # The upstream repository's default branch may not be master;
@@ -538,12 +538,12 @@ EOS
 
       # HOMEBREW_UPDATE_FORCE and HOMEBREW_UPDATE_PREINSTALL aren't modified here so ignore subshell warning.
       # shellcheck disable=SC2030
-      if [[ "${UPSTREAM_REPOSITORY_URL}" = "https://github.com/"* ]]
+      if [[ "${UPSTREAM_REPOSITORY_URL}" == "https://github.com/"* ]]
       then
         UPSTREAM_REPOSITORY="${UPSTREAM_REPOSITORY_URL#https://github.com/}"
         UPSTREAM_REPOSITORY="${UPSTREAM_REPOSITORY%.git}"
 
-        if [[ "${DIR}" = "${HOMEBREW_REPOSITORY}" && -n "${HOMEBREW_UPDATE_TO_TAG}" ]]
+        if [[ "${DIR}" == "${HOMEBREW_REPOSITORY}" && -n "${HOMEBREW_UPDATE_TO_TAG}" ]]
         then
           # Only try to `git fetch` when the upstream tags have changed
           # (so the API does not return 304: unmodified).
@@ -560,19 +560,21 @@ EOS
 
         # HOMEBREW_CURL is set by brew.sh (and isn't mispelt here)
         # shellcheck disable=SC2153
-        UPSTREAM_SHA_HTTP_CODE="$("${HOMEBREW_CURL}" \
-           "${CURL_DISABLE_CURLRC_ARGS[@]}" \
-           --silent --max-time 3 \
-           --location --no-remote-time --output /dev/null --write-out "%{http_code}" \
-           --dump-header "${DIR}/.git/GITHUB_HEADERS" \
-           --user-agent "${HOMEBREW_USER_AGENT_CURL}" \
-           --header "Accept: ${GITHUB_API_ACCEPT}" \
-           --header "If-None-Match: \"${GITHUB_API_ETAG}\"" \
-           "https://api.github.com/repos/${UPSTREAM_REPOSITORY}/${GITHUB_API_ENDPOINT}")"
+        UPSTREAM_SHA_HTTP_CODE="$(
+          "${HOMEBREW_CURL}" \
+            "${CURL_DISABLE_CURLRC_ARGS[@]}" \
+            --silent --max-time 3 \
+            --location --no-remote-time --output /dev/null --write-out "%{http_code}" \
+            --dump-header "${DIR}/.git/GITHUB_HEADERS" \
+            --user-agent "${HOMEBREW_USER_AGENT_CURL}" \
+            --header "Accept: ${GITHUB_API_ACCEPT}" \
+            --header "If-None-Match: \"${GITHUB_API_ETAG}\"" \
+            "https://api.github.com/repos/${UPSTREAM_REPOSITORY}/${GITHUB_API_ENDPOINT}"
+        )"
 
         # Touch FETCH_HEAD to confirm we've checked for an update.
         [[ -f "${DIR}/.git/FETCH_HEAD" ]] && touch "${DIR}/.git/FETCH_HEAD"
-        [[ -z "${HOMEBREW_UPDATE_FORCE}" ]] && [[ "${UPSTREAM_SHA_HTTP_CODE}" = "304" ]] && exit
+        [[ -z "${HOMEBREW_UPDATE_FORCE}" ]] && [[ "${UPSTREAM_SHA_HTTP_CODE}" == "304" ]] && exit
       elif [[ -n "${HOMEBREW_UPDATE_PREINSTALL}" ]]
       then
         FORCE_AUTO_UPDATE="$(git config homebrew.forceautoupdate 2>/dev/null || echo "false")"
@@ -583,7 +585,6 @@ EOS
         fi
       fi
 
-
       # HOMEBREW_VERBOSE isn't modified here so ignore subshell warning.
       # shellcheck disable=SC2030
       if [[ -n "${HOMEBREW_VERBOSE}" ]]
@@ -606,7 +607,7 @@ EOS
           # Reprint fetch errors to stderr
           [[ -f "${tmp_failure_file}" ]] && cat "${tmp_failure_file}" 1>&2
 
-          if [[ "${UPSTREAM_SHA_HTTP_CODE}" = "404" ]]
+          if [[ "${UPSTREAM_SHA_HTTP_CODE}" == "404" ]]
           then
             TAP="${DIR#${HOMEBREW_LIBRARY}/Taps/}"
             echo "${TAP} does not exist! Run \`brew untap ${TAP}\` to remove it." >>"${update_failed_file}"
@@ -614,7 +615,7 @@ EOS
             echo "Fetching ${DIR} failed!" >>"${update_failed_file}"
 
             if [[ -f "${tmp_failure_file}" ]] &&
-               [[ "$(<"${tmp_failure_file}")" = "fatal: couldn't find remote ref refs/heads/${UPSTREAM_BRANCH_DIR}" ]]
+               [[ "$(cat "${tmp_failure_file}")" == "fatal: couldn't find remote ref refs/heads/${UPSTREAM_BRANCH_DIR}" ]]
             then
               echo "${DIR}" >>"${missing_remote_ref_dirs_file}"
             fi
@@ -638,7 +639,7 @@ EOS
 
   if [[ -f "${missing_remote_ref_dirs_file}" ]]
   then
-    HOMEBREW_MISSING_REMOTE_REF_DIRS="$(<"${missing_remote_ref_dirs_file}")"
+    HOMEBREW_MISSING_REMOTE_REF_DIRS="$(cat "${missing_remote_ref_dirs_file}")"
     rm -f "${missing_remote_ref_dirs_file}"
     export HOMEBREW_MISSING_REMOTE_REF_DIRS
   fi
@@ -647,9 +648,10 @@ EOS
   do
     # HOMEBREW_UPDATE_PREINSTALL wasn't modified in subshell.
     # shellcheck disable=SC2031
-    if [[ -n "${HOMEBREW_INSTALL_FROM_API}" ]] && [[ -n "${HOMEBREW_UPDATE_PREINSTALL}" ]] &&
-       [[ "${DIR}" = "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" ||
-          "${DIR}" = "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-cask" ]]
+    if [[ -n "${HOMEBREW_INSTALL_FROM_API}" ]] &&
+       [[ -n "${HOMEBREW_UPDATE_PREINSTALL}" ]] &&
+       [[ "${DIR}" == "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-core" || \
+          "${DIR}" == "${HOMEBREW_LIBRARY}/Taps/homebrew/homebrew-cask" ]]
     then
       continue
     fi
@@ -672,8 +674,8 @@ EOS
     then
       simulate_from_current_branch "${DIR}" "${TAP_VAR}" "${UPSTREAM_BRANCH}" "${CURRENT_REVISION}"
     elif [[ -z "${HOMEBREW_UPDATE_FORCE}" ]] &&
-         [[ "${PREFETCH_REVISION}" = "${POSTFETCH_REVISION}" ]] &&
-         [[ "${CURRENT_REVISION}" = "${POSTFETCH_REVISION}" ]]
+         [[ "${PREFETCH_REVISION}" == "${POSTFETCH_REVISION}" ]] &&
+         [[ "${CURRENT_REVISION}" == "${POSTFETCH_REVISION}" ]]
     then
       export HOMEBREW_UPDATE_BEFORE"${TAP_VAR}"="${CURRENT_REVISION}"
       export HOMEBREW_UPDATE_AFTER"${TAP_VAR}"="${CURRENT_REVISION}"
@@ -687,18 +689,17 @@ EOS
 
   # HOMEBREW_UPDATE_PREINSTALL wasn't modified in subshell.
   # shellcheck disable=SC2031
-  if [[ -n "${HOMEBREW_UPDATED}" ||
-        -n "${HOMEBREW_UPDATE_FAILED}" ||
-        -n "${HOMEBREW_MISSING_REMOTE_REF_DIRS}" ||
-        -n "${HOMEBREW_UPDATE_FORCE}" ||
-        -d "${HOMEBREW_LIBRARY}/LinkedKegs" ||
-        ! -f "${HOMEBREW_CACHE}/all_commands_list.txt" ||
-        (-n "${HOMEBREW_DEVELOPER}" && -z "${HOMEBREW_UPDATE_PREINSTALL}") ]]
+  if [[ -n "${HOMEBREW_UPDATED}" ]] ||
+     [[ -n "${HOMEBREW_UPDATE_FAILED}" ]] ||
+     [[ -n "${HOMEBREW_MISSING_REMOTE_REF_DIRS}" ]] ||
+     [[ -n "${HOMEBREW_UPDATE_FORCE}" ]] ||
+     [[ -d "${HOMEBREW_LIBRARY}/LinkedKegs" ]] ||
+     [[ ! -f "${HOMEBREW_CACHE}/all_commands_list.txt" ]] ||
+     [[ -n "${HOMEBREW_DEVELOPER}" && -z "${HOMEBREW_UPDATE_PREINSTALL}" ]]
   then
     brew update-report "$@"
     return $?
-  elif [[ -z "${HOMEBREW_UPDATE_PREINSTALL}" &&
-          -z "${HOMEBREW_QUIET}" ]]
+  elif [[ -z "${HOMEBREW_UPDATE_PREINSTALL}" && -z "${HOMEBREW_QUIET}" ]]
   then
     echo "Already up-to-date."
   fi
diff --git a/Library/Homebrew/cmd/vendor-install.sh b/Library/Homebrew/cmd/vendor-install.sh
index 3d0b0797ef..4d436ee9a8 100644
--- a/Library/Homebrew/cmd/vendor-install.sh
+++ b/Library/Homebrew/cmd/vendor-install.sh
@@ -14,7 +14,7 @@ VENDOR_DIR="${HOMEBREW_LIBRARY}/Homebrew/vendor"
 # Built from https://github.com/Homebrew/homebrew-portable-ruby.
 if [[ -n "${HOMEBREW_MACOS}" ]]
 then
-  if [[ "${HOMEBREW_PROCESSOR}" = "Intel" ]]
+  if [[ "${HOMEBREW_PROCESSOR}" == "Intel" ]]
   then
     ruby_FILENAME="portable-ruby-2.6.3_2.yosemite.bottle.tar.gz"
     ruby_SHA="b065e5e3783954f3e65d8d3a6377ca51649bfcfa21b356b0dd70490f74c6bd86"
@@ -26,7 +26,7 @@ then
       ruby_FILENAME="portable-ruby-2.6.3_2.x86_64_linux.bottle.tar.gz"
       ruby_SHA="97e639a64dcec285392b53ad804b5334c324f1d2a8bdc2b5087b8bf8051e332f"
       ;;
-    *)
+    *) ;;
   esac
 fi
 
@@ -43,13 +43,15 @@ then
   then
     ruby_URLs+=("${HOMEBREW_BOTTLE_DOMAIN}/bottles-portable-ruby/${ruby_FILENAME}")
   fi
-  ruby_URLs+=("https://ghcr.io/v2/homebrew/portable-ruby/portable-ruby/blobs/sha256:${ruby_SHA}"
-              "https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.3_2/${ruby_FILENAME}")
+  ruby_URLs+=(
+    "https://ghcr.io/v2/homebrew/portable-ruby/portable-ruby/blobs/sha256:${ruby_SHA}"
+    "https://github.com/Homebrew/homebrew-portable-ruby/releases/download/2.6.3_2/${ruby_FILENAME}"
+  )
   ruby_URL="${ruby_URLs[0]}"
 fi
 
 check_linux_glibc_version() {
-  if [[ -z ${HOMEBREW_LINUX} || -z ${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION} ]]
+  if [[ -z "${HOMEBREW_LINUX}" || -z "${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION}" ]]
   then
     return 0
   fi
@@ -58,15 +60,15 @@ check_linux_glibc_version() {
   local glibc_version_major
   local glibc_version_minor
 
-  local minimum_required_major=${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION%.*}
-  local minimum_required_minor=${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION#*.}
+  local minimum_required_major="${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION%.*}"
+  local minimum_required_minor="${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION#*.}"
 
-  if [[ $(/usr/bin/ldd --version) =~ \ [0-9]\.[0-9]+ ]]
+  if [[ "$(/usr/bin/ldd --version)" =~ \ [0-9]\.[0-9]+ ]]
   then
-    glibc_version=${BASH_REMATCH[0]// /}
-    glibc_version_major=${glibc_version%.*}
-    glibc_version_minor=${glibc_version#*.}
-    if (( glibc_version_major < minimum_required_major || glibc_version_minor < minimum_required_minor ))
+    glibc_version="${BASH_REMATCH[0]// /}"
+    glibc_version_major="${glibc_version%.*}"
+    glibc_version_minor="${glibc_version#*.}"
+    if ((glibc_version_major < minimum_required_major || glibc_version_minor < minimum_required_minor))
     then
       odie "Vendored tools require system Glibc ${HOMEBREW_LINUX_MINIMUM_GLIBC_VERSION} or later (yours is ${glibc_version})."
     fi
@@ -77,7 +79,8 @@ check_linux_glibc_version() {
 
 # Execute the specified command, and suppress stderr unless HOMEBREW_STDERR is set.
 quiet_stderr() {
-  if [[ -z "${HOMEBREW_STDERR}" ]]; then
+  if [[ -z "${HOMEBREW_STDERR}" ]]
+  then
     command "$@" 2>/dev/null
   else
     command "$@"
@@ -180,13 +183,14 @@ EOS
     sha="$(sha256sum "${CACHED_LOCATION}" | cut -d' ' -f1)"
   elif [[ -x "$(type -P ruby)" ]]
   then
-    sha="$(ruby <<EOSCRIPT
-            require 'digest/sha2'
-            digest = Digest::SHA256.new
-            File.open('${CACHED_LOCATION}', 'rb') { |f| digest.update(f.read) }
-            puts digest.hexdigest
+    sha="$(
+      ruby <<EOSCRIPT
+require 'digest/sha2'
+digest = Digest::SHA256.new
+File.open('${CACHED_LOCATION}', 'rb') { |f| digest.update(f.read) }
+puts digest.hexdigest
 EOSCRIPT
-)"
+    )"
   else
     odie "Cannot verify checksum ('shasum' or 'sha256sum' not found)!"
   fi
@@ -261,9 +265,9 @@ homebrew-vendor-install() {
       --debug)               HOMEBREW_DEBUG=1 ;;
       --*)                   ;;
       -*)
-        [[ "${option}" = *v* ]] && HOMEBREW_VERBOSE=1
-        [[ "${option}" = *q* ]] && HOMEBREW_QUIET=1
-        [[ "${option}" = *d* ]] && HOMEBREW_DEBUG=1
+        [[ "${option}" == *v* ]] && HOMEBREW_VERBOSE=1
+        [[ "${option}" == *q* ]] && HOMEBREW_QUIET=1
+        [[ "${option}" == *d* ]] && HOMEBREW_DEBUG=1
         ;;
       *)
         [[ -n "${VENDOR_NAME}" ]] && odie "This command does not take multiple vendor targets!"
@@ -282,7 +286,7 @@ homebrew-vendor-install() {
   VENDOR_FILENAME="${!filename_var}"
   VENDOR_SHA="${!sha_var}"
   VENDOR_URL="${!url_var}"
-  VENDOR_VERSION="$(<"${VENDOR_DIR}/portable-${VENDOR_NAME}-version")"
+  VENDOR_VERSION="$(cat "${VENDOR_DIR}/portable-${VENDOR_NAME}-version")"
 
   if [[ -z "${VENDOR_URL}" || -z "${VENDOR_SHA}" ]]
   then
@@ -292,7 +296,7 @@ homebrew-vendor-install() {
   # Expand the name to an array of variables
   # The array name must be "${VENDOR_NAME}_URLs"! Otherwise substitution errors will occur!
   # shellcheck disable=SC2086
-  read -r -a VENDOR_URLs <<< "$(eval "echo "\$\{${url_var}s[@]\}"")"
+  read -r -a VENDOR_URLs <<<"$(eval "echo "\$\{${url_var}s[@]\}"")"
 
   CACHED_LOCATION="${HOMEBREW_CACHE}/${VENDOR_FILENAME}"
 
diff --git a/Library/Homebrew/dev-cmd/rubocop.sh b/Library/Homebrew/dev-cmd/rubocop.sh
index aeb452c2ca..bc1b8ca769 100644
--- a/Library/Homebrew/dev-cmd/rubocop.sh
+++ b/Library/Homebrew/dev-cmd/rubocop.sh
@@ -14,7 +14,8 @@ homebrew-rubocop() {
   GEM_VERSION="$("${HOMEBREW_RUBY_PATH}" "${RUBY_DISABLE_OPTIONS}" -rrbconfig -e 'puts RbConfig::CONFIG["ruby_version"]')"
   GEM_HOME="${HOMEBREW_LIBRARY}/Homebrew/vendor/bundle/ruby/${GEM_VERSION}"
 
-  if ! [[ -f "${GEM_HOME}/bin/rubocop" ]]; then
+  if ! [[ -f "${GEM_HOME}/bin/rubocop" ]]
+  then
     "${HOMEBREW_BREW_FILE}" install-bundler-gems
   fi
 
diff --git a/Library/Homebrew/items.sh b/Library/Homebrew/items.sh
index 5d481096ac..40d0c48ead 100644
--- a/Library/Homebrew/items.sh
+++ b/Library/Homebrew/items.sh
@@ -1,13 +1,14 @@
 homebrew-items() {
   local items
   local sed_extended_regex_flag
-  local find_filter=$1
-  local sed_filter=$2
-  local grep_filter=$3
+  local find_filter="$1"
+  local sed_filter="$2"
+  local grep_filter="$3"
 
   # HOMEBREW_MACOS is set by brew.sh
   # shellcheck disable=SC2154
-  if [[ -n "${HOMEBREW_MACOS}" ]]; then
+  if [[ -n "${HOMEBREW_MACOS}" ]]
+  then
     sed_extended_regex_flag="-E"
   else
     sed_extended_regex_flag="-r"
@@ -15,7 +16,7 @@ homebrew-items() {
 
   # HOMEBREW_REPOSITORY is set by brew.sh
   # shellcheck disable=SC2154
-  items="$( \
+  items="$(
     find "${HOMEBREW_REPOSITORY}/Library/Taps" \
          -type d \( \
            -name "${find_filter}" -o \
@@ -25,15 +26,15 @@ homebrew-items() {
            -name spec -o \
            -name vendor \
           \) \
-         -prune -false -o -name '*\.rb' | \
-    sed "${sed_extended_regex_flag}" \
-      -e 's/\.rb//g' \
-      -e 's_.*/Taps/(.*)/(home|linux)brew-_\1/_' \
-      -e "${sed_filter}" \
+         -prune -false -o -name '*\.rb' |
+      sed "${sed_extended_regex_flag}" \
+          -e 's/\.rb//g' \
+          -e 's_.*/Taps/(.*)/(home|linux)brew-_\1/_' \
+          -e "${sed_filter}"
   )"
   local shortnames
   shortnames="$(echo "${items}" | cut -d "/" -f 3)"
-  echo -e "${items}\n${shortnames}" | \
-    grep -v "${grep_filter}" | \
+  echo -e "${items}\n${shortnames}" |
+    grep -v "${grep_filter}" |
     sort -uf
 }
diff --git a/Library/Homebrew/prefix.sh b/Library/Homebrew/prefix.sh
index 11b0899dd9..836a5552e3 100644
--- a/Library/Homebrew/prefix.sh
+++ b/Library/Homebrew/prefix.sh
@@ -5,20 +5,27 @@
 # HOMEBREW_PREFIX and HOMEBREW_REPOSITORY are set by brew.sh
 # shellcheck disable=SC2154
 homebrew-prefix() {
-  while [[ "$#" -gt 0 ]]; do
-      case $1 in
-          # check we actually have --prefix and not e.g. --prefixsomething
-          --prefix) local prefix="1"; shift ;;
-          # reject all other flags
-          -*) return 1 ;;
-          *) [ -n "${formula}" ] && return 1; local formula="$1"; shift ;;
-      esac
+  while [[ "$#" -gt 0 ]]
+  do
+    case "$1" in
+      # check we actually have --prefix and not e.g. --prefixsomething
+      --prefix)
+        local prefix="1"; shift
+        ;;
+      # reject all other flags
+      -*) return 1 ;;
+      *)
+        [[ -n "${formula}" ]] && return 1
+        local formula="$1"; shift
+        ;;
+    esac
   done
-  [ -z "${prefix}" ] && return 1
-  [ -z "${formula}" ] && echo "${HOMEBREW_PREFIX}" && return 0
+  [[ -z "${prefix}" ]] && return 1
+  [[ -z "${formula}" ]] && echo "${HOMEBREW_PREFIX}" && return 0
 
   local formula_path
-  if [ -f "${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core/Formula/${formula}.rb" ]; then
+  if [[ -f "${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core/Formula/${formula}.rb" ]]
+  then
     formula_path="${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core/Formula/${formula}.rb"
   else
     formula_path="$(
@@ -26,7 +33,7 @@ homebrew-prefix() {
       echo "${HOMEBREW_REPOSITORY}/Library/Taps"/*/*/{Formula/,HomebrewFormula/,}"${formula}.rb"
     )"
   fi
-  [ -z "${formula_path}" ] && return 1
+  [[ -z "${formula_path}" ]] && return 1
 
   echo "${HOMEBREW_PREFIX}/opt/${formula}"
   return 0
diff --git a/Library/Homebrew/shims/linux/super/make b/Library/Homebrew/shims/linux/super/make
index 534d3153c3..44f124b152 100755
--- a/Library/Homebrew/shims/linux/super/make
+++ b/Library/Homebrew/shims/linux/super/make
@@ -4,13 +4,19 @@
 # HOMEBREW_LIBRARY is set by bin/brew
 # shellcheck disable=SC2154,SC2250
 pathremove() {
-        local IFS=':' NEWPATH="" DIR="" PATHVARIABLE=${2:-PATH}
-        for DIR in ${!PATHVARIABLE} ; do
-                if [ "${DIR}" != "$1" ] ; then
-                  NEWPATH=${NEWPATH:+$NEWPATH:}${DIR}
-                fi
-        done
-        export "${PATHVARIABLE}"="${NEWPATH}"
+  local IFS=':'
+  local NEWPATH=""
+  local DIR=""
+  local PATHVARIABLE="${2:-PATH}"
+
+  for DIR in ${!PATHVARIABLE}
+  do
+    if [[ "${DIR}" != "$1" ]]
+    then
+      NEWPATH="${NEWPATH:+$NEWPATH:}${DIR}"
+    fi
+  done
+  export "${PATHVARIABLE}"="${NEWPATH}"
 }
 
 SAVED_PATH="${PATH}"
diff --git a/Library/Homebrew/shims/mac/super/pkg-config b/Library/Homebrew/shims/mac/super/pkg-config
index b0666879ba..dff6ec882d 100755
--- a/Library/Homebrew/shims/mac/super/pkg-config
+++ b/Library/Homebrew/shims/mac/super/pkg-config
@@ -4,7 +4,8 @@
 # shellcheck disable=SC2154
 pkg_config="${HOMEBREW_OPT}/pkg-config/bin/pkg-config"
 
-if [ -z "${HOMEBREW_SDKROOT}" ]; then
+if [[ -z "${HOMEBREW_SDKROOT}" ]]
+then
   exec "${pkg_config}" "$@"
 fi
 
diff --git a/Library/Homebrew/shims/mac/super/ruby b/Library/Homebrew/shims/mac/super/ruby
index 914a680aac..447616dd8a 100755
--- a/Library/Homebrew/shims/mac/super/ruby
+++ b/Library/Homebrew/shims/mac/super/ruby
@@ -9,8 +9,9 @@ source "${HOMEBREW_LIBRARY}/Homebrew/shims/utils.sh"
 
 try_exec_non_system "${SHIM_FILE}" "$@"
 
-if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]; then
-  export SDKROOT=${HOMEBREW_SDKROOT}
+if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]
+then
+  export SDKROOT="${HOMEBREW_SDKROOT}"
 fi
 
 safe_exec "/usr/bin/${SHIM_FILE}" "$@"
diff --git a/Library/Homebrew/shims/mac/super/swift b/Library/Homebrew/shims/mac/super/swift
index 3b8949f31d..9531b7ceff 100755
--- a/Library/Homebrew/shims/mac/super/swift
+++ b/Library/Homebrew/shims/mac/super/swift
@@ -7,8 +7,9 @@
 # shellcheck disable=SC2154
 source "${HOMEBREW_LIBRARY}/Homebrew/shims/utils.sh"
 
-if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]; then
-  export SDKROOT=${HOMEBREW_SDKROOT}
+if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]
+then
+  export SDKROOT="${HOMEBREW_SDKROOT}"
 fi
 
 try_exec_non_system "swift" "$@"
diff --git a/Library/Homebrew/shims/mac/super/xcrun b/Library/Homebrew/shims/mac/super/xcrun
index 100a606b9a..cdc01a9a32 100755
--- a/Library/Homebrew/shims/mac/super/xcrun
+++ b/Library/Homebrew/shims/mac/super/xcrun
@@ -7,18 +7,21 @@
 # These could be used in conjunction with `--sdk` which ignores SDKROOT.
 # HOMEBREW_DEVELOPER_DIR, HOMEBREW_SDKROOT and HOMEBREW_PREFER_CLT_PROXIES are set by extend/ENV/super.rb
 # shellcheck disable=SC2154
-if [[ "$*" =~ (^| )-?-show-sdk-(path|version|build) && -n "${HOMEBREW_DEVELOPER_DIR}" ]]; then
-  export DEVELOPER_DIR=${HOMEBREW_DEVELOPER_DIR}
+if [[ "$*" =~ (^| )-?-show-sdk-(path|version|build) && -n "${HOMEBREW_DEVELOPER_DIR}" ]]
+then
+  export DEVELOPER_DIR="${HOMEBREW_DEVELOPER_DIR}"
 else
   # Some build tools set DEVELOPER_DIR, so discard it
   unset DEVELOPER_DIR
 fi
 
-if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]; then
-  export SDKROOT=${HOMEBREW_SDKROOT}
+if [[ -z "${SDKROOT}" && -n "${HOMEBREW_SDKROOT}" ]]
+then
+  export SDKROOT="${HOMEBREW_SDKROOT}"
 fi
 
-if [ $# -eq 0 ]; then
+if [[ $# -eq 0 ]]
+then
   exec /usr/bin/xcrun "$@"
 fi
 
@@ -27,38 +30,45 @@ case "$1" in
   -*) exec /usr/bin/xcrun "$@" ;;
 esac
 
-arg0=$1
+arg0="$1"
 shift
 
 exe="/usr/bin/${arg0}"
-if [[ -x "${exe}" ]]; then
-  if [[ -n "${HOMEBREW_PREFER_CLT_PROXIES}" ]]; then
+if [[ -x "${exe}" ]]
+then
+  if [[ -n "${HOMEBREW_PREFER_CLT_PROXIES}" ]]
+  then
     exec "${exe}" "$@"
-  elif [[ -z "${HOMEBREW_SDKROOT}" || ! -d "${HOMEBREW_SDKROOT}" ]]; then
+  elif [[ -z "${HOMEBREW_SDKROOT}" || ! -d "${HOMEBREW_SDKROOT}" ]]
+  then
     exec "${exe}" "$@"
   fi
 fi
 
-SUPERBIN=$(cd "${0%/*}" && pwd -P)
+SUPERBIN="$(cd "${0%/*}" && pwd -P)"
 
-exe=$(/usr/bin/xcrun --find "${arg0}" 2>/dev/null)
-if [[ -x "${exe}" && "${exe%/*}" != "${SUPERBIN}" ]]; then
+exe="$(/usr/bin/xcrun --find "${arg0}" 2>/dev/null)"
+if [[ -x "${exe}" && "${exe%/*}" != "${SUPERBIN}" ]]
+then
   exec "${exe}" "$@"
 fi
 
-old_IFS=${IFS}
-IFS=:
-for path in ${PATH}; do
-  if [ "${path}" = "${SUPERBIN}" ]; then
+old_IFS="${IFS}"
+IFS=':'
+for path in ${PATH}
+do
+  if [[ "${path}" == "${SUPERBIN}" ]]
+  then
     continue
   fi
 
   exe="${path}/${arg0}"
-  if [ -x "${exe}" ]; then
+  if [[ -x "${exe}" ]]
+  then
     exec "${exe}" "$@"
   fi
 done
-IFS=${old_IFS}
+IFS="${old_IFS}"
 
 echo >&2 "
 Failed to execute ${arg0} ${*}
diff --git a/Library/Homebrew/shims/scm/git b/Library/Homebrew/shims/scm/git
index 6cdadfd13b..a969376479 100755
--- a/Library/Homebrew/shims/scm/git
+++ b/Library/Homebrew/shims/scm/git
@@ -7,9 +7,9 @@
 # SHIM_FILE is set by shims/utils.sh
 # HOMEBREW_GIT is set by brew.sh
 # HOMEBREW_SVN is from the user environment.
-# HOMEBREW_PREFIX is set extend/ENV/super.rb
+# HOMEBREW_PREFIX is set by extend/ENV/super.rb
 # shellcheck disable=SC2154
-if [ -z "${HOMEBREW_LIBRARY}" ]
+if [[ -z "${HOMEBREW_LIBRARY}" ]]
 then
   echo "${0##*/}: This shim is internal and must be run via brew." >&2
   exit 1
diff --git a/Library/Homebrew/shims/super/cc b/Library/Homebrew/shims/super/cc
index fbe556f8b0..617d728a38 100755
--- a/Library/Homebrew/shims/super/cc
+++ b/Library/Homebrew/shims/super/cc
@@ -1,11 +1,11 @@
 #!/bin/sh
 # Make sure this shim uses the same Ruby interpreter that is used by Homebrew.
-if [ -z "$HOMEBREW_RUBY_PATH" ]
+if [[ -z "${HOMEBREW_RUBY_PATH}" ]]
 then
   echo "${0##*/}: The build tool has reset ENV; --env=std required." >&2
   exit 1
 fi
-exec "$HOMEBREW_RUBY_PATH" --enable-frozen-string-literal --disable=gems,did_you_mean,rubyopt -x "$0" "$@"
+exec "${HOMEBREW_RUBY_PATH}" --enable-frozen-string-literal --disable=gems,did_you_mean,rubyopt -x "$0" "$@"
 #!/usr/bin/env ruby -W0
 
 require "pathname"
diff --git a/Library/Homebrew/shims/utils.sh b/Library/Homebrew/shims/utils.sh
index 13e4d2be27..f573ed9fa0 100644
--- a/Library/Homebrew/shims/utils.sh
+++ b/Library/Homebrew/shims/utils.sh
@@ -1,7 +1,10 @@
 set +o posix
 
 quiet_safe_cd() {
-  cd "$1" &>/dev/null || { echo "Error: failed to cd to $1" >&2; exit 1; }
+  cd "$1" &>/dev/null || {
+    echo "Error: failed to cd to $1" >&2
+    exit 1
+  }
 }
 
 absdir() {
@@ -25,7 +28,7 @@ realpath() {
   while [[ -L "${path}" ]]
   do
     dest="$(readlink "${path}")"
-    if [[ "${dest}" = "/"* ]]
+    if [[ "${dest}" == "/"* ]]
     then
       path="${dest}"
     else
@@ -54,11 +57,11 @@ safe_exec() {
     return
   fi
   # prevent fork-bombs
-  if [[ "$(lowercase "${arg0}")" = "${SHIM_FILE}" || "$(realpath "${arg0}")" = "${SHIM_REAL}" ]]
+  if [[ "$(lowercase "${arg0}")" == "${SHIM_FILE}" || "$(realpath "${arg0}")" == "${SHIM_REAL}" ]]
   then
     return
   fi
-  if [[ "${HOMEBREW}" = "print-path" ]]
+  if [[ "${HOMEBREW}" == "print-path" ]]
   then
     local dir
     dir="$(quiet_safe_cd "${arg0%/*}/" && pwd)"
@@ -71,25 +74,23 @@ safe_exec() {
 }
 
 try_exec_non_system() {
-	local file="$1"
+  local file="$1"
   shift
 
-	IFS=$'\n'
-	for path in $(type -aP "${file}")
-	do
-	  if [[ "${path}" != "/usr/bin/${file}" ]]
-	  then
-	    safe_exec "${path}" "$@"
-	  fi
-	done
-	unset IFS
+  local path
+  while read -r path
+  do
+    if [[ "${path}" != "/usr/bin/${file}" ]]
+    then
+      safe_exec "${path}" "$@"
+    fi
+  done < <(type -aP "${file}")
 }
 
-
 SHIM_FILE="${0##*/}"
 SHIM_REAL="$(realpath "$0")"
 
-if [[ "$1" = --homebrew=* ]]
+if [[ "$1" == "--homebrew="* ]]
 then
   HOMEBREW="${1:11}"
   shift
diff --git a/Library/Homebrew/utils/analytics.sh b/Library/Homebrew/utils/analytics.sh
index fe26e0bbed..62d38a01cb 100644
--- a/Library/Homebrew/utils/analytics.sh
+++ b/Library/Homebrew/utils/analytics.sh
@@ -10,7 +10,7 @@ migrate-legacy-uuid-file() {
 
   if [[ -f "${legacy_uuid_file}" ]]
   then
-    analytics_uuid="$(<"${legacy_uuid_file}")"
+    analytics_uuid="$(cat "${legacy_uuid_file}")"
     if [[ -n "${analytics_uuid}" ]]
     then
       git config --file="${HOMEBREW_REPOSITORY}/.git/config" --replace-all homebrew.analyticsuuid "${analytics_uuid}" 2>/dev/null
@@ -32,7 +32,7 @@ setup-analytics() {
   local message_seen analytics_disabled
   message_seen="$(git config --file="${git_config_file}" --get homebrew.analyticsmessage 2>/dev/null)"
   analytics_disabled="$(git config --file="${git_config_file}" --get homebrew.analyticsdisabled 2>/dev/null)"
-  if [[ "${message_seen}" != "true" || "${analytics_disabled}" = "true" ]]
+  if [[ "${message_seen}" != "true" || "${analytics_disabled}" == "true" ]]
   then
     # Internal variable for brew's use, to differentiate from user-supplied setting
     export HOMEBREW_NO_ANALYTICS_THIS_RUN="1"
diff --git a/Library/Homebrew/utils/lock.sh b/Library/Homebrew/utils/lock.sh
index 010ea5ca14..8cc5f997ce 100644
--- a/Library/Homebrew/utils/lock.sh
+++ b/Library/Homebrew/utils/lock.sh
@@ -8,7 +8,7 @@ lock() {
   local lock_dir="${HOMEBREW_PREFIX}/var/homebrew/locks"
   local lock_file="${lock_dir}/${name}"
   [[ -d "${lock_dir}" ]] || mkdir -p "${lock_dir}"
-  if ! [[ -w "${lock_dir}" ]]
+  if [[ ! -w "${lock_dir}" ]]
   then
     odie <<EOS
 Can't create ${name} lock in ${lock_dir}!
diff --git a/Library/Homebrew/utils/ruby.sh b/Library/Homebrew/utils/ruby.sh
index 581d65e56b..4941c44880 100644
--- a/Library/Homebrew/utils/ruby.sh
+++ b/Library/Homebrew/utils/ruby.sh
@@ -8,14 +8,14 @@ which_all() {
   fi
 
   local executable entries entry retcode=1
-  IFS=':' read -r -a entries <<< "${PATH}"  # `readarray -d ':' -t` seems not applicable on WSL Bash
+  IFS=':' read -r -a entries <<<"${PATH}" # `readarray -d ':' -t` seems not applicable on WSL Bash
   for entry in "${entries[@]}"
   do
     executable="${entry}/$1"
     if [[ -x "${executable}" ]]
     then
       echo "${executable}"
-      retcode=0  # present
+      retcode=0 # present
     fi
   done
 
@@ -46,7 +46,8 @@ find_ruby() {
     local ruby_exec
     while read -r ruby_exec
     do
-      if test_ruby "${ruby_exec}"; then
+      if test_ruby "${ruby_exec}"
+      then
         echo "${ruby_exec}"
         break
       fi
@@ -90,7 +91,7 @@ setup-ruby-path() {
   local upgrade_fail
   local install_fail
 
-  if [[ -n ${HOMEBREW_MACOS} ]]
+  if [[ -n "${HOMEBREW_MACOS}" ]]
   then
     upgrade_fail="Failed to upgrade Homebrew Portable Ruby!"
     install_fail="Failed to install Homebrew Portable Ruby (and your system version is too old)!"
@@ -109,8 +110,8 @@ If there's no Homebrew Portable Ruby available for your processor:
   vendor_ruby_root="${vendor_dir}/portable-ruby/current"
   vendor_ruby_path="${vendor_ruby_root}/bin/ruby"
   vendor_ruby_terminfo="${vendor_ruby_root}/share/terminfo"
-  vendor_ruby_latest_version=$(<"${vendor_dir}/portable-ruby-version")
-  vendor_ruby_current_version=$(readlink "${vendor_ruby_root}")
+  vendor_ruby_latest_version="$(cat "${vendor_dir}/portable-ruby-version")"
+  vendor_ruby_current_version="$(readlink "${vendor_ruby_root}")"
 
   unset HOMEBREW_RUBY_PATH
 
@@ -123,12 +124,12 @@ If there's no Homebrew Portable Ruby available for your processor:
   then
     HOMEBREW_RUBY_PATH="${vendor_ruby_path}"
     TERMINFO_DIRS="${vendor_ruby_terminfo}"
-    if [[ ${vendor_ruby_current_version} != "${vendor_ruby_latest_version}" ]]
+    if [[ "${vendor_ruby_current_version}" != "${vendor_ruby_latest_version}" ]]
     then
       brew vendor-install ruby || odie "${upgrade_fail}"
     fi
   else
-    HOMEBREW_RUBY_PATH=$(find_ruby)
+    HOMEBREW_RUBY_PATH="$(find_ruby)"
     if need_vendored_ruby
     then
       brew vendor-install ruby || odie "${install_fail}"
diff --git a/bin/brew b/bin/brew
index 78eaa033b7..191d585868 100755
--- a/bin/brew
+++ b/bin/brew
@@ -114,7 +114,7 @@ then
     # Skip if variable value is empty.
     [[ -z "${!VAR}" ]] && continue
 
-    FILTERED_ENV+=( "${VAR}=${!VAR}" )
+    FILTERED_ENV+=("${VAR}=${!VAR}")
   done
 
   exec /usr/bin/env -i "${FILTERED_ENV[@]}" /bin/bash "${HOMEBREW_LIBRARY}/Homebrew/brew.sh" "$@"
diff --git a/docs/Common-Issues.md b/docs/Common-Issues.md
index 3386ef6d6e..77d261f0b7 100644
--- a/docs/Common-Issues.md
+++ b/docs/Common-Issues.md
@@ -17,14 +17,14 @@ After running `brew update`, you receive a Git error warning about untracked fil
 This is caused by an old bug in in the `update` code that has long since been fixed. However, the nature of the bug requires that you do the following:
 
 ```sh
-cd $(brew --repository)
+cd "$(brew --repository)"
 git reset --hard FETCH_HEAD
 ```
 
 If `brew doctor` still complains about uncommitted modifications, also run this command:
 
 ```sh
-cd $(brew --repository)/Library
+cd "$(brew --repository)/Library"
 git clean -fd
 ```
 
@@ -71,7 +71,7 @@ Please report this bug:
 This happens because an old version of the upgrade command is hanging around for some reason. The fix:
 
 ```sh
-cd $(brew --repository)/Library/Contributions/examples
+cd "$(brew --repository)/Library/Contributions/examples"
 git clean -n # if this doesn't list anything that you want to keep, then
 git clean -f # this will remove untracked files
 ```
diff --git a/docs/FAQ.md b/docs/FAQ.md
index e77e6693b8..abaa48eba8 100644
--- a/docs/FAQ.md
+++ b/docs/FAQ.md
@@ -55,7 +55,7 @@ Homebrew doesn't support arbitrary mixing and matching of formula versions, so e
 Which is usually: `~/Library/Caches/Homebrew`
 
 ## My Mac `.app`s don’t find Homebrew utilities!
-GUI apps on macOS don’t have Homebrew's prefix in their `PATH` by default. If you're on Mountain Lion or later, you can fix this by running `sudo launchctl config user path "$(brew --prefix)/bin:$PATH"` and then rebooting, as documented in `man launchctl`. Note that this sets the launchctl `PATH` for *all users*. For earlier versions of macOS, see [this page](https://developer.apple.com/legacy/library/qa/qa1067/_index.html).
+GUI apps on macOS don’t have Homebrew's prefix in their `PATH` by default. If you're on Mountain Lion or later, you can fix this by running `sudo launchctl config user path "$(brew --prefix)/bin:${PATH}"` and then rebooting, as documented in `man launchctl`. Note that this sets the launchctl `PATH` for *all users*. For earlier versions of macOS, see [this page](https://developer.apple.com/legacy/library/qa/qa1067/_index.html).
 
 ## How do I contribute to Homebrew?
 Read our [contribution guidelines](https://github.com/Homebrew/brew/blob/HEAD/CONTRIBUTING.md#contributing-to-homebrew).
@@ -84,7 +84,7 @@ We aim to bottle everything.
 ```sh
 brew install hub
 brew update
-cd $(brew --repository)
+cd "$(brew --repository)"
 hub pull someone_else
 ```
 
diff --git a/docs/Formula-Cookbook.md b/docs/Formula-Cookbook.md
index 7605d10bc0..81e30f56a0 100644
--- a/docs/Formula-Cookbook.md
+++ b/docs/Formula-Cookbook.md
@@ -361,7 +361,7 @@ Everything is built on Git, so contribution is easy:
 
 ```sh
 brew update # required in more ways than you think (initialises the brew git repository if you don't already have it)
-cd $(brew --repository homebrew/core)
+cd "$(brew --repository homebrew/core)"
 # Create a new git branch for your formula so your pull request is easy to
 # modify if any changes come up during review.
 git checkout -b <some-descriptive-name> origin/master
diff --git a/docs/Gems,-Eggs-and-Perl-Modules.md b/docs/Gems,-Eggs-and-Perl-Modules.md
index 22ea9e0f1a..f50bfd0d65 100644
--- a/docs/Gems,-Eggs-and-Perl-Modules.md
+++ b/docs/Gems,-Eggs-and-Perl-Modules.md
@@ -118,7 +118,7 @@ Then put the appropriate incantation in your shell’s startup, e.g. for
 [`local::lib`](https://metacpan.org/pod/local::lib) docs.
 
 ```sh
-eval $(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)
+eval "$(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)"
 ```
 
 Now (after you restart your shell) `cpan` or `perl -MCPAN -eshell` etc.
diff --git a/docs/Homebrew-and-Python.md b/docs/Homebrew-and-Python.md
index 68f030a9d2..a3514e32fb 100644
--- a/docs/Homebrew-and-Python.md
+++ b/docs/Homebrew-and-Python.md
@@ -77,7 +77,7 @@ For brewed Python, modules installed with `pip3` or `python3 setup.py install` w
 The system Python may not know which compiler flags to set in order to build bindings for software installed in Homebrew so you may need to run:
 
 ```sh
-CFLAGS=-I$(brew --prefix)/include LDFLAGS=-L$(brew --prefix)/lib pip install <package>
+CFLAGS="-I$(brew --prefix)/include" LDFLAGS="-L$(brew --prefix)/lib" pip install <package>
 ```
 
 ## Virtualenv
diff --git a/docs/Homebrew-linuxbrew-core-Maintainer-Guide.md b/docs/Homebrew-linuxbrew-core-Maintainer-Guide.md
index 339fb9b921..882680975f 100644
--- a/docs/Homebrew-linuxbrew-core-Maintainer-Guide.md
+++ b/docs/Homebrew-linuxbrew-core-Maintainer-Guide.md
@@ -44,9 +44,9 @@ variable, or let `hub fork` add a remote for you.
 
 ```bash
 brew install hub
-cd $(brew --repository homebrew/core)
+cd "$(brew --repository homebrew/core)"
 git remote add homebrew https://github.com/Homebrew/homebrew-core.git
-hub fork --remote-name=$HOMEBREW_GITHUB_USER
+hub fork --remote-name="${HOMEBREW_GITHUB_USER}"
 ```
 
 Now, let's make sure that our local branch `master` is clean and that
@@ -56,7 +56,7 @@ your fork is up-to-date with Homebrew/linuxbrew-core:
 git checkout master
 git fetch origin master
 git reset --hard origin/master
-git push --force $HOMEBREW_GITHUB_USER master
+git push --force "${HOMEBREW_GITHUB_USER}" master
 ```
 
 Strictly speaking, there is no need for `git reset --hard
@@ -220,8 +220,9 @@ manually, tap `Homebrew/homebrew-linux-dev` and run the following
 command where the merge commit is `HEAD`:
 
 ```sh
-for formula in $(brew find-formulae-to-bottle); do
-  brew request-bottle $formula
+for formula in $(brew find-formulae-to-bottle)
+do
+  brew request-bottle "${formula}"
 done
 ```
 
diff --git a/docs/Homebrew-on-Linux.md b/docs/Homebrew-on-Linux.md
index fd22b35b39..23a99feca9 100644
--- a/docs/Homebrew-on-Linux.md
+++ b/docs/Homebrew-on-Linux.md
@@ -31,10 +31,10 @@ The prefix `/home/linuxbrew/.linuxbrew` was chosen so that users without admin a
 Follow the *Next steps* instructions to add Homebrew to your `PATH` and to your bash shell profile script, either `~/.profile` on Debian/Ubuntu or `~/.bash_profile` on CentOS/Fedora/Red Hat.
 
 ```sh
-test -d ~/.linuxbrew && eval $(~/.linuxbrew/bin/brew shellenv)
-test -d /home/linuxbrew/.linuxbrew && eval $(/home/linuxbrew/.linuxbrew/bin/brew shellenv)
-test -r ~/.bash_profile && echo "eval \$($(brew --prefix)/bin/brew shellenv)" >>~/.bash_profile
-echo "eval \$($(brew --prefix)/bin/brew shellenv)" >>~/.profile
+test -d ~/.linuxbrew && eval "$(~/.linuxbrew/bin/brew shellenv)"
+test -d /home/linuxbrew/.linuxbrew && eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"
+test -r ~/.bash_profile && echo "eval \"\$($(brew --prefix)/bin/brew shellenv)\"" >>~/.bash_profile
+echo "eval \"\$($(brew --prefix)/bin/brew shellenv)\"" >>~/.profile
 ```
 
 You're done! Try installing a package:
@@ -86,7 +86,7 @@ Extract or `git clone` Homebrew wherever you want. Use `/home/linuxbrew/.linuxbr
 git clone https://github.com/Homebrew/brew ~/.linuxbrew/Homebrew
 mkdir ~/.linuxbrew/bin
 ln -s ~/.linuxbrew/Homebrew/bin/brew ~/.linuxbrew/bin
-eval $(~/.linuxbrew/bin/brew shellenv)
+eval "$(~/.linuxbrew/bin/brew shellenv)"
 ```
 
 ## Homebrew on Linux Community
diff --git a/docs/How-To-Open-a-Homebrew-Pull-Request.md b/docs/How-To-Open-a-Homebrew-Pull-Request.md
index c34bb19b32..e9749b3706 100644
--- a/docs/How-To-Open-a-Homebrew-Pull-Request.md
+++ b/docs/How-To-Open-a-Homebrew-Pull-Request.md
@@ -15,7 +15,7 @@ Depending on the change you want to make, you need to send the pull request to t
   * This creates a personal remote repository that you can push to. This is needed because only Homebrew maintainers have push access to the main repositories.
 2. Change to the directory containing your Homebrew installation:
     ```sh
-    cd $(brew --repository)
+    cd "$(brew --repository)"
     ```
 3. Add your pushable forked repository as a new remote:
     ```sh
@@ -29,7 +29,7 @@ Depending on the change you want to make, you need to send the pull request to t
   * This creates a personal remote repository that you can push to. This is needed because only Homebrew maintainers have push access to the main repositories.
 2. Change to the directory containing Homebrew formulae:
     ```sh
-    cd $(brew --repository homebrew/core)
+    cd "$(brew --repository homebrew/core)"
     ```
 3. Add your pushable forked repository as a new remote:
     ```sh
diff --git a/docs/How-to-Build-Software-Outside-Homebrew-with-Homebrew-keg-only-Dependencies.md b/docs/How-to-Build-Software-Outside-Homebrew-with-Homebrew-keg-only-Dependencies.md
index 724fa0c4e7..7bbd82d94c 100644
--- a/docs/How-to-Build-Software-Outside-Homebrew-with-Homebrew-keg-only-Dependencies.md
+++ b/docs/How-to-Build-Software-Outside-Homebrew-with-Homebrew-keg-only-Dependencies.md
@@ -27,13 +27,13 @@ Useful, reliable alternatives exist should you wish to use `keg_only` tools outs
 You can set flags to give configure scripts or Makefiles a nudge in the right direction. An example of flag setting:
 
 ```sh
-./configure --prefix=/Users/Dave/Downloads CFLAGS=-I$(brew --prefix)/opt/openssl/include LDFLAGS=-L$(brew --prefix)/opt/openssl/lib
+./configure --prefix=/Users/Dave/Downloads CFLAGS="-I$(brew --prefix)/opt/openssl/include" LDFLAGS="-L$(brew --prefix)/opt/openssl/lib"
 ```
 
 An example using `pip`:
 
 ```sh
-CFLAGS=-I$(brew --prefix)/opt/icu4c/include LDFLAGS=-L$(brew --prefix)/opt/icu4c/lib pip install pyicu
+CFLAGS="-I$(brew --prefix)/opt/icu4c/include" LDFLAGS="-L$(brew --prefix)/opt/icu4c/lib" pip install pyicu
 ```
 
 ### `PATH` modification
@@ -41,7 +41,7 @@ CFLAGS=-I$(brew --prefix)/opt/icu4c/include LDFLAGS=-L$(brew --prefix)/opt/icu4c
 You can temporarily prepend your `PATH` with the tool’s `bin` directory, such as:
 
 ```sh
-export PATH=$(brew --prefix)/opt/openssl/bin:$PATH
+export PATH="$(brew --prefix)/opt/openssl/bin:${PATH}"
 ```
 
 This will prepend that folder to your `PATH`, ensuring any build script that searches the `PATH` will find it first.
@@ -55,7 +55,7 @@ If the tool you are attempting to build is [pkg-config](https://en.wikipedia.org
 An example of this is:
 
 ```sh
-export PKG_CONFIG_PATH=$(brew --prefix)/opt/openssl/lib/pkgconfig
+export PKG_CONFIG_PATH="$(brew --prefix)/opt/openssl/lib/pkgconfig"
 ```
 
 If you’re curious about the `PKG_CONFIG_PATH` variable `man pkg-config` goes into more detail.
diff --git a/docs/Manpage.md b/docs/Manpage.md
index b3a118223e..0077a6517c 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -572,7 +572,7 @@ Print export statements. When run in a shell, this installation of Homebrew will
 
 The variables `HOMEBREW_PREFIX`, `HOMEBREW_CELLAR` and `HOMEBREW_REPOSITORY` are also exported to avoid querying them multiple times.
 The variable `HOMEBREW_SHELLENV_PREFIX` will be exported to avoid adding duplicate entries to the environment variables.
-Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval $(brew shellenv)`
+Consider adding evaluation of this command's output to your dotfiles (e.g. `~/.profile`, `~/.bash_profile`, or `~/.zprofile`) with: `eval "$(brew shellenv)"`
 
 ### `tap` [*`options`*] [*`user`*`/`*`repo`*] [*`URL`*]
 
diff --git a/docs/Shell-Completion.md b/docs/Shell-Completion.md
index e30de1f8f1..f1c2768dfe 100644
--- a/docs/Shell-Completion.md
+++ b/docs/Shell-Completion.md
@@ -13,13 +13,16 @@ Shell completions for external Homebrew commands are not automatically installed
 To make Homebrew's completions available in `bash`, you must source the definitions as part of your shell's startup. Add the following to your `~/.bash_profile` (or, if it doesn't exist, `~/.profile`):
 
 ```sh
-if type brew &>/dev/null; then
+if type brew &>/dev/null
+then
   HOMEBREW_PREFIX="$(brew --prefix)"
-  if [[ -r "${HOMEBREW_PREFIX}/etc/profile.d/bash_completion.sh" ]]; then
+  if [[ -r "${HOMEBREW_PREFIX}/etc/profile.d/bash_completion.sh" ]]
+  then
     source "${HOMEBREW_PREFIX}/etc/profile.d/bash_completion.sh"
   else
-    for COMPLETION in "${HOMEBREW_PREFIX}/etc/bash_completion.d/"*; do
-      [[ -r "$COMPLETION" ]] && source "$COMPLETION"
+    for COMPLETION in "${HOMEBREW_PREFIX}/etc/bash_completion.d/"*
+    do
+      [[ -r "${COMPLETION}" ]] && source "${COMPLETION}"
     done
   fi
 fi
@@ -35,8 +38,9 @@ If you are using the `bash` formula as your shell (i.e. `bash` >= v4) you should
 To make Homebrew's completions available in `zsh`, you must get the Homebrew-managed zsh site-functions on your `FPATH` before initialising `zsh`'s completion facility. Add the following to your `~/.zshrc` file:
 
 ```sh
-if type brew &>/dev/null; then
-  FPATH=$(brew --prefix)/share/zsh/site-functions:$FPATH
+if type brew &>/dev/null
+then
+  FPATH="$(brew --prefix)/share/zsh/site-functions:${FPATH}"
 
   autoload -Uz compinit
   compinit
@@ -46,7 +50,7 @@ fi
 This must be done before `compinit` is called. Note that if you are using Oh My Zsh, it will call `compinit` for you, so this must be done before you call `oh-my-zsh.sh`. This may be done by appending the following line to your `~/.zprofile` after Homebrew's initialization, instead of modifying your `~/.zshrc` as above:
 
 ```sh
-FPATH=$(brew --prefix)/share/zsh/site-functions:$FPATH
+FPATH="$(brew --prefix)/share/zsh/site-functions:${FPATH}"
 ```
 
 You may also need to forcibly rebuild `zcompdump`:
diff --git a/docs/Tips-N'-Tricks.md b/docs/Tips-N'-Tricks.md
index c0491bce8d..1110862ff1 100644
--- a/docs/Tips-N'-Tricks.md
+++ b/docs/Tips-N'-Tricks.md
@@ -28,14 +28,14 @@ In the case of Erlang, this requires renaming the file from `otp_src_R13B03` to
 
 `brew --cache -s erlang` will print the correct name of the cached
 download. This means instead of manually renaming a formula, you can
-run `mv the_tarball $(brew --cache -s <formula>)`.
+run `mv the_tarball "$(brew --cache -s <formula>)"`.
 
 You can also pre-cache the download by using the command `brew fetch <formula>` which also displays the SHA-256 hash. This can be useful for updating formulae to new versions.
 
 ## Installing stuff without the Xcode CLT
 
 ```sh
-brew sh          # or: eval $(brew --env)
+brew sh          # or: eval "$(brew --env)"
 gem install ronn # or c-programs
 ```
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 83f0533b60..c046ffa9b6 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "BREW" "1" "August 2021" "Homebrew" "brew"
+.TH "BREW" "1" "September 2021" "Homebrew" "brew"
 .
 .SH "NAME"
 \fBbrew\fR \- The Missing Package Manager for macOS (or Linux)
@@ -796,7 +796,7 @@ Search for \fItext\fR in the given database\.
 Print export statements\. When run in a shell, this installation of Homebrew will be added to your \fBPATH\fR, \fBMANPATH\fR, and \fBINFOPATH\fR\.
 .
 .P
-The variables \fBHOMEBREW_PREFIX\fR, \fBHOMEBREW_CELLAR\fR and \fBHOMEBREW_REPOSITORY\fR are also exported to avoid querying them multiple times\. The variable \fBHOMEBREW_SHELLENV_PREFIX\fR will be exported to avoid adding duplicate entries to the environment variables\. Consider adding evaluation of this command\'s output to your dotfiles (e\.g\. \fB~/\.profile\fR, \fB~/\.bash_profile\fR, or \fB~/\.zprofile\fR) with: \fBeval $(brew shellenv)\fR
+The variables \fBHOMEBREW_PREFIX\fR, \fBHOMEBREW_CELLAR\fR and \fBHOMEBREW_REPOSITORY\fR are also exported to avoid querying them multiple times\. The variable \fBHOMEBREW_SHELLENV_PREFIX\fR will be exported to avoid adding duplicate entries to the environment variables\. Consider adding evaluation of this command\'s output to your dotfiles (e\.g\. \fB~/\.profile\fR, \fB~/\.bash_profile\fR, or \fB~/\.zprofile\fR) with: \fBeval "$(brew shellenv)"\fR
 .
 .SS "\fBtap\fR [\fIoptions\fR] [\fIuser\fR\fB/\fR\fIrepo\fR] [\fIURL\fR]"
 Tap a formula repository\.