From 05f912b109486321657d4fd74ebbd3949d1ae1b7 Mon Sep 17 00:00:00 2001
From: neo <arklove@qq.com>
Date: Mon, 1 Nov 2021 18:05:38 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E6=9B=B4=E6=96=B0=E5=8E=9F=E5=A7=8B?=
 =?UTF-8?q?=E8=84=9A=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 install-origin.sh | 631 +++++++++++++++++++++++++++++++---------------
 1 file changed, 428 insertions(+), 203 deletions(-)

diff --git a/install-origin.sh b/install-origin.sh
index fe3b14e..fe6624a 100755
--- a/install-origin.sh
+++ b/install-origin.sh
@@ -6,31 +6,37 @@ abort() {
   exit 1
 }
 
-if [ -z "${BASH_VERSION:-}" ]; then
+if [ -z "${BASH_VERSION:-}" ]
+then
   abort "Bash is required to interpret this script."
 fi
 
 # Check if script is run non-interactively (e.g. CI)
 # If it is run non-interactively we should not prompt for passwords.
-if [[ ! -t 0 || -n "${CI-}" ]]; then
+if [[ ! -t 0 || -n "${CI-}" ]]
+then
   NONINTERACTIVE=1
 fi
 
 # First check OS.
 OS="$(uname)"
-if [[ "$OS" == "Linux" ]]; then
+if [[ "${OS}" == "Linux" ]]
+then
   HOMEBREW_ON_LINUX=1
-elif [[ "$OS" != "Darwin" ]]; then
+elif [[ "${OS}" != "Darwin" ]]
+then
   abort "Homebrew is only supported on macOS and Linux."
 fi
 
 # Required installation paths. To install elsewhere (which is unsupported)
 # you can untar https://github.com/Homebrew/brew/tarball/master
 # anywhere you like.
-if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+then
   UNAME_MACHINE="$(/usr/bin/uname -m)"
 
-  if [[ "$UNAME_MACHINE" == "arm64" ]]; then
+  if [[ "${UNAME_MACHINE}" == "arm64" ]]
+  then
     # On ARM macOS, this script installs to /opt/homebrew only
     HOMEBREW_PREFIX="/opt/homebrew"
     HOMEBREW_REPOSITORY="${HOMEBREW_PREFIX}"
@@ -40,9 +46,9 @@ if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
     HOMEBREW_REPOSITORY="${HOMEBREW_PREFIX}/Homebrew"
   fi
   HOMEBREW_CACHE="${HOME}/Library/Caches/Homebrew"
-  HOMEBREW_CORE_DEFAULT_GIT_REMOTE="https://github.com/Homebrew/homebrew-core"
 
-  STAT="stat -f"
+  STAT_FLAG="-f"
+  PERMISSION_FORMAT="%A"
   CHOWN="/usr/sbin/chown"
   CHGRP="/usr/bin/chgrp"
   GROUP="admin"
@@ -54,43 +60,49 @@ else
   # and ~/.linuxbrew (which is unsupported) if run interactively.
   HOMEBREW_PREFIX_DEFAULT="/home/linuxbrew/.linuxbrew"
   HOMEBREW_CACHE="${HOME}/.cache/Homebrew"
-  HOMEBREW_CORE_DEFAULT_GIT_REMOTE="https://github.com/Homebrew/linuxbrew-core"
 
-  STAT="stat --printf"
+  STAT_FLAG="--printf"
+  PERMISSION_FORMAT="%a"
   CHOWN="/bin/chown"
   CHGRP="/bin/chgrp"
   GROUP="$(id -gn)"
   TOUCH="/bin/touch"
 fi
 HOMEBREW_BREW_DEFAULT_GIT_REMOTE="https://github.com/Homebrew/brew"
+HOMEBREW_CORE_DEFAULT_GIT_REMOTE="https://github.com/Homebrew/homebrew-core"
 
 # Use remote URLs of Homebrew repositories from environment if set.
 HOMEBREW_BREW_GIT_REMOTE="${HOMEBREW_BREW_GIT_REMOTE:-"${HOMEBREW_BREW_DEFAULT_GIT_REMOTE}"}"
 HOMEBREW_CORE_GIT_REMOTE="${HOMEBREW_CORE_GIT_REMOTE:-"${HOMEBREW_CORE_DEFAULT_GIT_REMOTE}"}"
 # The URLs with and without the '.git' suffix are the same Git remote. Do not prompt.
-if [[ "$HOMEBREW_BREW_GIT_REMOTE" == "${HOMEBREW_BREW_DEFAULT_GIT_REMOTE}.git" ]]; then
+if [[ "${HOMEBREW_BREW_GIT_REMOTE}" == "${HOMEBREW_BREW_DEFAULT_GIT_REMOTE}.git" ]]
+then
   HOMEBREW_BREW_GIT_REMOTE="${HOMEBREW_BREW_DEFAULT_GIT_REMOTE}"
 fi
-if [[ "$HOMEBREW_CORE_GIT_REMOTE" == "${HOMEBREW_CORE_DEFAULT_GIT_REMOTE}.git" ]]; then
+if [[ "${HOMEBREW_CORE_GIT_REMOTE}" == "${HOMEBREW_CORE_DEFAULT_GIT_REMOTE}.git" ]]
+then
   HOMEBREW_CORE_GIT_REMOTE="${HOMEBREW_CORE_DEFAULT_GIT_REMOTE}"
 fi
 export HOMEBREW_{BREW,CORE}_GIT_REMOTE
 
 # TODO: bump version when new macOS is released or announced
-MACOS_NEWEST_UNSUPPORTED="12.0"
+MACOS_NEWEST_UNSUPPORTED="13.0"
 # TODO: bump version when new macOS is released
-MACOS_OLDEST_SUPPORTED="10.14"
+MACOS_OLDEST_SUPPORTED="10.15"
 
 # For Homebrew on Linux
-REQUIRED_RUBY_VERSION=2.6  # https://github.com/Homebrew/brew/pull/6556
+REQUIRED_RUBY_VERSION=2.6    # https://github.com/Homebrew/brew/pull/6556
 REQUIRED_GLIBC_VERSION=2.13  # https://docs.brew.sh/Homebrew-on-Linux#requirements
+REQUIRED_CURL_VERSION=7.41.0 # HOMEBREW_MINIMUM_CURL_VERSION in brew.sh in Homebrew/brew
+REQUIRED_GIT_VERSION=2.7.0   # HOMEBREW_MINIMUM_GIT_VERSION in brew.sh in Homebrew/brew
 
 # no analytics during installation
 export HOMEBREW_NO_ANALYTICS_THIS_RUN=1
 export HOMEBREW_NO_ANALYTICS_MESSAGE_OUTPUT=1
 
 # string formatters
-if [[ -t 1 ]]; then
+if [[ -t 1 ]]
+then
   tty_escape() { printf "\033[%sm" "$1"; }
 else
   tty_escape() { :; }
@@ -102,21 +114,34 @@ tty_red="$(tty_mkbold 31)"
 tty_bold="$(tty_mkbold 39)"
 tty_reset="$(tty_escape 0)"
 
+unset HAVE_SUDO_ACCESS # unset this from the environment
+
 have_sudo_access() {
+  if [[ ! -x "/usr/bin/sudo" ]]
+  then
+    return 1
+  fi
+
   local -a args
-  if [[ -n "${SUDO_ASKPASS-}" ]]; then
+  if [[ -n "${SUDO_ASKPASS-}" ]]
+  then
     args=("-A")
-  elif [[ -n "${NONINTERACTIVE-}" ]]; then
+  elif [[ -n "${NONINTERACTIVE-}" ]]
+  then
     args=("-n")
   fi
 
-  if [[ -z "${HAVE_SUDO_ACCESS-}" ]]; then
-    if [[ -n "${args[*]-}" ]]; then
+  if [[ -z "${HAVE_SUDO_ACCESS-}" ]]
+  then
+    if [[ -n "${args[*]-}" ]]
+    then
       SUDO="/usr/bin/sudo ${args[*]}"
     else
       SUDO="/usr/bin/sudo"
     fi
-    if [[ -n "${NONINTERACTIVE-}" ]]; then
+    if [[ -n "${NONINTERACTIVE-}" ]]
+    then
+      # Don't add quotes around ${SUDO} here
       ${SUDO} -l mkdir &>/dev/null
     else
       ${SUDO} -v && ${SUDO} -l mkdir &>/dev/null
@@ -124,18 +149,20 @@ have_sudo_access() {
     HAVE_SUDO_ACCESS="$?"
   fi
 
-  if [[ -z "${HOMEBREW_ON_LINUX-}" ]] && [[ "$HAVE_SUDO_ACCESS" -ne 0 ]]; then
-    abort "Need sudo access on macOS (e.g. the user $USER needs to be an Administrator)!"
+  if [[ -z "${HOMEBREW_ON_LINUX-}" ]] && [[ "${HAVE_SUDO_ACCESS}" -ne 0 ]]
+  then
+    abort "Need sudo access on macOS (e.g. the user ${USER} needs to be an Administrator)!"
   fi
 
-  return "$HAVE_SUDO_ACCESS"
+  return "${HAVE_SUDO_ACCESS}"
 }
 
 shell_join() {
   local arg
   printf "%s" "$1"
   shift
-  for arg in "$@"; do
+  for arg in "$@"
+  do
     printf " "
     printf "%s" "${arg// /\ }"
   done
@@ -154,15 +181,18 @@ warn() {
 }
 
 execute() {
-  if ! "$@"; then
+  if ! "$@"
+  then
     abort "$(printf "Failed during: %s" "$(shell_join "$@")")"
   fi
 }
 
 execute_sudo() {
   local -a args=("$@")
-  if have_sudo_access; then
-    if [[ -n "${SUDO_ASKPASS-}" ]]; then
+  if have_sudo_access
+  then
+    if [[ -n "${SUDO_ASKPASS-}" ]]
+    then
       args=("-A" "${args[@]}")
     fi
     ohai "/usr/bin/sudo" "${args[@]}"
@@ -175,15 +205,16 @@ execute_sudo() {
 
 getc() {
   local save_state
-  save_state=$(/bin/stty -g)
+  save_state="$(/bin/stty -g)"
   /bin/stty raw -echo
-  IFS= read -r -n 1 -d '' "$@"
-  /bin/stty "$save_state"
+  IFS='' read -r -n 1 -d '' "$@"
+  /bin/stty "${save_state}"
 }
 
 ring_bell() {
   # Use the shell's audible bell.
-  if [[ -t 1 ]]; then
+  if [[ -t 1 ]]
+  then
     printf "\a"
   fi
 }
@@ -194,13 +225,17 @@ wait_for_user() {
   echo "Press RETURN to continue or any other key to abort"
   getc c
   # we test for \r and \n because some stuff does \r instead
-  if ! [[ "$c" == $'\r' || "$c" == $'\n' ]]; then
+  if ! [[ "${c}" == $'\r' || "${c}" == $'\n' ]]
+  then
     exit 1
   fi
 }
 
 major_minor() {
-  echo "${1%%.*}.$(x="${1#*.}"; echo "${x%%.*}")"
+  echo "${1%%.*}.$(
+    x="${1#*.}"
+    echo "${x%%.*}"
+  )"
 }
 
 version_gt() {
@@ -214,11 +249,13 @@ version_lt() {
 }
 
 should_install_command_line_tools() {
-  if [[ -n "${HOMEBREW_ON_LINUX-}" ]]; then
+  if [[ -n "${HOMEBREW_ON_LINUX-}" ]]
+  then
     return 1
   fi
 
-  if version_gt "$macos_version" "10.13"; then
+  if version_gt "${macos_version}" "10.13"
+  then
     ! [[ -e "/Library/Developer/CommandLineTools/usr/bin/git" ]]
   else
     ! [[ -e "/Library/Developer/CommandLineTools/usr/bin/git" ]] ||
@@ -227,11 +264,11 @@ should_install_command_line_tools() {
 }
 
 get_permission() {
-  $STAT "%A" "$1"
+  stat "${STAT_FLAG}" "${PERMISSION_FORMAT}" "$1"
 }
 
 user_only_chmod() {
-  [[ -d "$1" ]] && [[ "$(get_permission "$1")" != "755" ]]
+  [[ -d "$1" ]] && [[ "$(get_permission "$1")" != 75[0145] ]]
 }
 
 exists_but_not_writable() {
@@ -239,7 +276,7 @@ exists_but_not_writable() {
 }
 
 get_owner() {
-  $STAT "%u" "$1"
+  stat "${STAT_FLAG}" "%u" "$1"
 }
 
 file_not_owned() {
@@ -247,64 +284,107 @@ file_not_owned() {
 }
 
 get_group() {
-  $STAT "%g" "$1"
+  stat "${STAT_FLAG}" "%g" "$1"
 }
 
 file_not_grpowned() {
-  [[ " $(id -G "$USER") " != *" $(get_group "$1") "*  ]]
+  [[ " $(id -G "${USER}") " != *" $(get_group "$1") "* ]]
 }
 
 # Please sync with 'test_ruby()' in 'Library/Homebrew/utils/ruby.sh' from Homebrew/brew repository.
 test_ruby() {
-  if [[ ! -x $1 ]]
+  if [[ ! -x "$1" ]]
   then
     return 1
   fi
 
   "$1" --enable-frozen-string-literal --disable=gems,did_you_mean,rubyopt -rrubygems -e \
     "abort if Gem::Version.new(RUBY_VERSION.to_s.dup).to_s.split('.').first(2) != \
-              Gem::Version.new('$REQUIRED_RUBY_VERSION').to_s.split('.').first(2)" 2>/dev/null
+              Gem::Version.new('${REQUIRED_RUBY_VERSION}').to_s.split('.').first(2)" 2>/dev/null
+}
+
+test_curl() {
+  if [[ ! -x "$1" ]]
+  then
+    return 1
+  fi
+
+  local curl_version_output curl_name_and_version
+  curl_version_output="$("$1" --version 2>/dev/null)"
+  curl_name_and_version="${curl_version_output%% (*}"
+  version_ge "$(major_minor "${curl_name_and_version##* }")" "$(major_minor "${REQUIRED_CURL_VERSION}")"
+}
+
+test_git() {
+  if [[ ! -x "$1" ]]
+  then
+    return 1
+  fi
+
+  local git_version_output
+  git_version_output="$("$1" --version 2>/dev/null)"
+  version_ge "$(major_minor "${git_version_output##* }")" "$(major_minor "${REQUIRED_GIT_VERSION}")"
+}
+
+# Search given executable in PATH (remove dependency for `which` command)
+which() {
+  # Alias to Bash built-in command `type -P`
+  type -P "$@"
+}
+
+# Search PATH for the specified program that satisfies Homebrew requirements
+# function which is set above
+# shellcheck disable=SC2230
+find_tool() {
+  if [[ $# -ne 1 ]]
+  then
+    return 1
+  fi
+
+  local executable
+  while read -r executable
+  do
+    if "test_$1" "${executable}"
+    then
+      echo "${executable}"
+      break
+    fi
+  done < <(which -a "$1")
 }
 
 no_usable_ruby() {
-  local ruby_exec
-  IFS=$'\n' # Do word splitting on new lines only
-  for ruby_exec in $(which -a ruby 2>/dev/null); do
-    if test_ruby "$ruby_exec"; then
-      IFS=$' \t\n' # Restore IFS to its default value
-      return 1
-    fi
-  done
-  IFS=$' \t\n' # Restore IFS to its default value
-  return 0
+  [[ -z "$(find_tool ruby)" ]]
 }
 
 outdated_glibc() {
   local glibc_version
-  glibc_version=$(ldd --version | head -n1 | grep -o '[0-9.]*$' | grep -o '^[0-9]\+\.[0-9]\+')
-  version_lt "$glibc_version" "$REQUIRED_GLIBC_VERSION"
+  glibc_version="$(ldd --version | head -n1 | grep -o '[0-9.]*$' | grep -o '^[0-9]\+\.[0-9]\+')"
+  version_lt "${glibc_version}" "${REQUIRED_GLIBC_VERSION}"
 }
 
 if [[ -n "${HOMEBREW_ON_LINUX-}" ]] && no_usable_ruby && outdated_glibc
 then
-    abort "$(cat <<-EOFABORT
-	Homebrew requires Ruby $REQUIRED_RUBY_VERSION which was not found on your system.
-	Homebrew portable Ruby requires Glibc version $REQUIRED_GLIBC_VERSION or newer,
-	and your Glibc version is too old.
-	See ${tty_underline}https://docs.brew.sh/Homebrew-on-Linux#requirements${tty_reset}
-	Install Ruby $REQUIRED_RUBY_VERSION and add its location to your PATH.
-	EOFABORT
-    )"
+  abort "$(
+    cat <<-EOFABORT
+Homebrew requires Ruby ${REQUIRED_RUBY_VERSION} which was not found on your system.
+Homebrew portable Ruby requires Glibc version ${REQUIRED_GLIBC_VERSION} or newer,
+and your Glibc version is too old.
+See ${tty_underline}https://docs.brew.sh/Homebrew-on-Linux#requirements${tty_reset}
+Install Ruby ${REQUIRED_RUBY_VERSION} and add its location to your PATH.
+EOFABORT
+  )"
 fi
 
 # USER isn't always set so provide a fall back for the installer and subprocesses.
-if [[ -z "${USER-}" ]]; then
+if [[ -z "${USER-}" ]]
+then
   USER="$(chomp "$(id -un)")"
   export USER
 fi
 
 # Invalidate sudo timestamp before exiting (if it wasn't active before).
-if ! /usr/bin/sudo -n -v 2>/dev/null; then
+if [[ -x /usr/bin/sudo ]] && ! /usr/bin/sudo -n -v 2>/dev/null
+then
   trap '/usr/bin/sudo -k' EXIT
 fi
 
@@ -313,45 +393,99 @@ fi
 cd "/usr" || exit 1
 
 ####################################################################### script
-if ! command -v git >/dev/null; then
-    abort "$(cat <<EOABORT
+if ! command -v git >/dev/null
+then
+  abort "$(
+    cat <<EOABORT
 You must install Git before installing Homebrew. See:
   ${tty_underline}https://docs.brew.sh/Installation${tty_reset}
 EOABORT
-)"
+  )"
+elif [[ -n "${HOMEBREW_ON_LINUX-}" ]]
+then
+  USABLE_GIT="$(find_tool git)"
+  if [[ -z "${USABLE_GIT}" ]]
+  then
+    abort "$(
+      cat <<-EOABORT
+Git that is available on your system does not satisfy Homebrew requirements.
+Please install Git ${REQUIRED_GIT_VERSION} or newer and add it to your PATH.
+EOABORT
+    )"
+  elif [[ "${USABLE_GIT}" != /usr/bin/git ]]
+  then
+    export HOMEBREW_GIT_PATH="${USABLE_GIT}"
+    ohai "Found Git: ${HOMEBREW_GIT_PATH}"
+  fi
 fi
 
-if ! command -v curl >/dev/null; then
-    abort "$(cat <<EOABORT
+if ! command -v curl >/dev/null
+then
+  abort "$(
+    cat <<EOABORT
 You must install cURL before installing Homebrew. See:
   ${tty_underline}https://docs.brew.sh/Installation${tty_reset}
 EOABORT
-)"
+  )"
+elif [[ -n "${HOMEBREW_ON_LINUX-}" ]]
+then
+  USABLE_CURL="$(find_tool curl)"
+  if [[ -z "${USABLE_CURL}" ]]
+  then
+    abort "$(
+      cat <<-EOABORT
+cURL that is available on your system does not satisfy Homebrew requirements.
+Please install cURL ${REQUIRED_CURL_VERSION} or newer and add it to your PATH.
+EOABORT
+    )"
+  elif [[ "${USABLE_CURL}" != /usr/bin/curl ]]
+  then
+    export HOMEBREW_CURL_PATH="${USABLE_CURL}"
+    ohai "Found cURL: ${HOMEBREW_CURL_PATH}"
+  fi
+fi
+
+# Set HOMEBREW_DEVELOPER on Linux systems where usable Git/cURL is not in /usr/bin
+if [[ -n "${HOMEBREW_ON_LINUX-}" && (-n "${HOMEBREW_CURL_PATH-}" || -n "${HOMEBREW_GIT_PATH-}") ]]
+then
+  ohai "Setting HOMEBREW_DEVELOPER to use Git/cURL not in /usr/bin"
+  export HOMEBREW_DEVELOPER=1
 fi
 
 # shellcheck disable=SC2016
 ohai 'Checking for `sudo` access (which may request your password).'
 
-if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+then
   have_sudo_access
 else
-  if [[ -n "${NONINTERACTIVE-}" ]] ||
-     [[ -w "${HOMEBREW_PREFIX_DEFAULT}" ]] ||
+  if [[ -w "${HOMEBREW_PREFIX_DEFAULT}" ]] ||
      [[ -w "/home/linuxbrew" ]] ||
-     [[ -w "/home" ]]; then
-    HOMEBREW_PREFIX="$HOMEBREW_PREFIX_DEFAULT"
+     [[ -w "/home" ]]
+  then
+    HOMEBREW_PREFIX="${HOMEBREW_PREFIX_DEFAULT}"
+  elif [[ -n "${NONINTERACTIVE-}" ]]
+  then
+    if have_sudo_access
+    then
+      HOMEBREW_PREFIX="${HOMEBREW_PREFIX_DEFAULT}"
+    else
+      abort "Insufficient permissions to install Homebrew to \"${HOMEBREW_PREFIX_DEFAULT}\"."
+    fi
   else
     trap exit SIGINT
-    if ! /usr/bin/sudo -n -v &>/dev/null; then
+    if ! /usr/bin/sudo -n -v &>/dev/null
+    then
       ohai "Select the Homebrew installation directory"
       echo "- ${tty_bold}Enter your password${tty_reset} to install to ${tty_underline}${HOMEBREW_PREFIX_DEFAULT}${tty_reset} (${tty_bold}recommended${tty_reset})"
-      echo "- ${tty_bold}Press Control-D${tty_reset} to install to ${tty_underline}$HOME/.linuxbrew${tty_reset}"
+      echo "- ${tty_bold}Press Control-D${tty_reset} to install to ${tty_underline}${HOME}/.linuxbrew${tty_reset}"
       echo "- ${tty_bold}Press Control-C${tty_reset} to cancel installation"
     fi
-    if have_sudo_access; then
-      HOMEBREW_PREFIX="$HOMEBREW_PREFIX_DEFAULT"
+    if have_sudo_access
+    then
+      HOMEBREW_PREFIX="${HOMEBREW_PREFIX_DEFAULT}"
     else
-      HOMEBREW_PREFIX="$HOME/.linuxbrew"
+      HOMEBREW_PREFIX="${HOME}/.linuxbrew"
     fi
     trap - SIGINT
   fi
@@ -359,58 +493,73 @@ else
 fi
 HOMEBREW_CORE="${HOMEBREW_REPOSITORY}/Library/Taps/homebrew/homebrew-core"
 
-if [[ "${EUID:-${UID}}" == "0" ]]; then
+if [[ "${EUID:-${UID}}" == "0" ]]
+then
   # Allow Azure Pipelines/GitHub Actions/Docker/Concourse/Kubernetes to do everything as root (as it's normal there)
   if ! [[ -f /proc/1/cgroup ]] ||
-     ! grep -E "azpl_job|actions_job|docker|garden|kubepods" -q /proc/1/cgroup; then
+     ! grep -E "azpl_job|actions_job|docker|garden|kubepods" -q /proc/1/cgroup
+  then
     abort "Don't run this as root!"
   fi
 fi
 
-if [[ -d "${HOMEBREW_PREFIX}" && ! -x "${HOMEBREW_PREFIX}" ]]; then
-  abort "$(cat <<EOABORT
+if [[ -d "${HOMEBREW_PREFIX}" && ! -x "${HOMEBREW_PREFIX}" ]]
+then
+  abort "$(
+    cat <<EOABORT
 The Homebrew prefix, ${HOMEBREW_PREFIX}, exists but is not searchable.
 If this is not intentional, please restore the default permissions and
 try running the installer again:
     sudo chmod 775 ${HOMEBREW_PREFIX}
 EOABORT
-)"
+  )"
 fi
 
-if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+then
   # On macOS, support 64-bit Intel and ARM
-  if [[ "$UNAME_MACHINE" != "arm64" ]] && [[ "$UNAME_MACHINE" != "x86_64" ]]; then
+  if [[ "${UNAME_MACHINE}" != "arm64" ]] && [[ "${UNAME_MACHINE}" != "x86_64" ]]
+  then
     abort "Homebrew is only supported on Intel and ARM processors!"
   fi
 else
   # On Linux, support only 64-bit Intel
-  if [[ "$UNAME_MACHINE" == "arm64" ]]; then
-    abort "$(cat <<EOABORT
+  if [[ "${UNAME_MACHINE}" == "arm64" ]]
+  then
+    abort "$(
+      cat <<EOABORT
 Homebrew on Linux is not supported on ARM processors.
 You can try an alternate installation method instead:
   ${tty_underline}https://docs.brew.sh/Homebrew-on-Linux#arm${tty_reset}
 EOABORT
-)"
-  elif [[ "$UNAME_MACHINE" != "x86_64" ]]; then
+    )"
+  elif [[ "${UNAME_MACHINE}" != "x86_64" ]]
+  then
     abort "Homebrew on Linux is only supported on Intel processors!"
   fi
 fi
 
-if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+then
   macos_version="$(major_minor "$(/usr/bin/sw_vers -productVersion)")"
-  if version_lt "$macos_version" "10.7"; then
-    abort "$(cat <<EOABORT
+  if version_lt "${macos_version}" "10.7"
+  then
+    abort "$(
+      cat <<EOABORT
 Your Mac OS X version is too old. See:
   ${tty_underline}https://github.com/mistydemeo/tigerbrew${tty_reset}
 EOABORT
-)"
-  elif version_lt "$macos_version" "10.10"; then
+    )"
+  elif version_lt "${macos_version}" "10.10"
+  then
     abort "Your OS X version is too old"
-  elif version_ge "$macos_version" "$MACOS_NEWEST_UNSUPPORTED" || \
-    version_lt "$macos_version" "$MACOS_OLDEST_SUPPORTED"; then
+  elif version_ge "${macos_version}" "${MACOS_NEWEST_UNSUPPORTED}" ||
+       version_lt "${macos_version}" "${MACOS_OLDEST_SUPPORTED}"
+  then
     who="We"
     what=""
-    if version_ge "$macos_version" "$MACOS_NEWEST_UNSUPPORTED"; then
+    if version_ge "${macos_version}" "${MACOS_NEWEST_UNSUPPORTED}"
+    then
       what="pre-release version"
     else
       who+=" (and Apple)"
@@ -419,14 +568,15 @@ EOABORT
     ohai "You are using macOS ${macos_version}."
     ohai "${who} do not provide support for this ${what}."
 
-    echo "$(cat <<EOS
+    echo "$(
+      cat <<EOS
 This installation may not succeed.
 After installation, you will encounter build failures with some formulae.
 Please create pull requests instead of asking for help on Homebrew\'s GitHub,
 Twitter or IRC. You are responsible for resolving any issues you experience
 while you are running this ${what}.
 EOS
-)
+    )
 "
   fi
 fi
@@ -441,17 +591,21 @@ echo "${HOMEBREW_REPOSITORY}"
 
 # Keep relatively in sync with
 # https://github.com/Homebrew/brew/blob/master/Library/Homebrew/keg.rb
-directories=(bin etc include lib sbin share opt var
-             Frameworks
-             etc/bash_completion.d lib/pkgconfig
-             share/aclocal share/doc share/info share/locale share/man
-             share/man/man1 share/man/man2 share/man/man3 share/man/man4
-             share/man/man5 share/man/man6 share/man/man7 share/man/man8
-             var/log var/homebrew var/homebrew/linked
-             bin/brew)
+directories=(
+  bin etc include lib sbin share opt var
+  Frameworks
+  etc/bash_completion.d lib/pkgconfig
+  share/aclocal share/doc share/info share/locale share/man
+  share/man/man1 share/man/man2 share/man/man3 share/man/man4
+  share/man/man5 share/man/man6 share/man/man7 share/man/man8
+  var/log var/homebrew var/homebrew/linked
+  bin/brew
+)
 group_chmods=()
-for dir in "${directories[@]}"; do
-  if exists_but_not_writable "${HOMEBREW_PREFIX}/${dir}"; then
+for dir in "${directories[@]}"
+do
+  if exists_but_not_writable "${HOMEBREW_PREFIX}/${dir}"
+  then
     group_chmods+=("${HOMEBREW_PREFIX}/${dir}")
   fi
 done
@@ -459,159 +613,206 @@ done
 # zsh refuses to read from these directories if group writable
 directories=(share/zsh share/zsh/site-functions)
 zsh_dirs=()
-for dir in "${directories[@]}"; do
+for dir in "${directories[@]}"
+do
   zsh_dirs+=("${HOMEBREW_PREFIX}/${dir}")
 done
 
-directories=(bin etc include lib sbin share var opt
-             share/zsh share/zsh/site-functions
-             var/homebrew var/homebrew/linked
-             Cellar Caskroom Frameworks)
+directories=(
+  bin etc include lib sbin share var opt
+  share/zsh share/zsh/site-functions
+  var/homebrew var/homebrew/linked
+  Cellar Caskroom Frameworks
+)
 mkdirs=()
-for dir in "${directories[@]}"; do
-  if ! [[ -d "${HOMEBREW_PREFIX}/${dir}" ]]; then
+for dir in "${directories[@]}"
+do
+  if ! [[ -d "${HOMEBREW_PREFIX}/${dir}" ]]
+  then
     mkdirs+=("${HOMEBREW_PREFIX}/${dir}")
   fi
 done
 
 user_chmods=()
-if [[ "${#zsh_dirs[@]}" -gt 0 ]]; then
-  for dir in "${zsh_dirs[@]}"; do
-    if user_only_chmod "${dir}"; then
+mkdirs_user_only=()
+if [[ "${#zsh_dirs[@]}" -gt 0 ]]
+then
+  for dir in "${zsh_dirs[@]}"
+  do
+    if [[ ! -d "${dir}" ]]
+    then
+      mkdirs_user_only+=("${dir}")
+    elif user_only_chmod "${dir}"
+    then
       user_chmods+=("${dir}")
     fi
   done
 fi
 
 chmods=()
-if [[ "${#group_chmods[@]}" -gt 0 ]]; then
+if [[ "${#group_chmods[@]}" -gt 0 ]]
+then
   chmods+=("${group_chmods[@]}")
 fi
-if [[ "${#user_chmods[@]}" -gt 0 ]]; then
+if [[ "${#user_chmods[@]}" -gt 0 ]]
+then
   chmods+=("${user_chmods[@]}")
 fi
 
 chowns=()
 chgrps=()
-if [[ "${#chmods[@]}" -gt 0 ]]; then
-  for dir in "${chmods[@]}"; do
-    if file_not_owned "${dir}"; then
+if [[ "${#chmods[@]}" -gt 0 ]]
+then
+  for dir in "${chmods[@]}"
+  do
+    if file_not_owned "${dir}"
+    then
       chowns+=("${dir}")
     fi
-    if file_not_grpowned "${dir}"; then
+    if file_not_grpowned "${dir}"
+    then
       chgrps+=("${dir}")
     fi
   done
 fi
 
-if [[ "${#group_chmods[@]}" -gt 0 ]]; then
+if [[ "${#group_chmods[@]}" -gt 0 ]]
+then
   ohai "The following existing directories will be made group writable:"
   printf "%s\n" "${group_chmods[@]}"
 fi
-if [[ "${#user_chmods[@]}" -gt 0 ]]; then
+if [[ "${#user_chmods[@]}" -gt 0 ]]
+then
   ohai "The following existing directories will be made writable by user only:"
   printf "%s\n" "${user_chmods[@]}"
 fi
-if [[ "${#chowns[@]}" -gt 0 ]]; then
+if [[ "${#chowns[@]}" -gt 0 ]]
+then
   ohai "The following existing directories will have their owner set to ${tty_underline}${USER}${tty_reset}:"
   printf "%s\n" "${chowns[@]}"
 fi
-if [[ "${#chgrps[@]}" -gt 0 ]]; then
+if [[ "${#chgrps[@]}" -gt 0 ]]
+then
   ohai "The following existing directories will have their group set to ${tty_underline}${GROUP}${tty_reset}:"
   printf "%s\n" "${chgrps[@]}"
 fi
-if [[ "${#mkdirs[@]}" -gt 0 ]]; then
+if [[ "${#mkdirs[@]}" -gt 0 ]]
+then
   ohai "The following new directories will be created:"
   printf "%s\n" "${mkdirs[@]}"
 fi
 
-if should_install_command_line_tools; then
+if should_install_command_line_tools
+then
   ohai "The Xcode Command Line Tools will be installed."
 fi
 
 non_default_repos=""
 additional_shellenv_commands=()
-if [[ "$HOMEBREW_BREW_DEFAULT_GIT_REMOTE" != "$HOMEBREW_BREW_GIT_REMOTE" ]]; then
+if [[ "${HOMEBREW_BREW_DEFAULT_GIT_REMOTE}" != "${HOMEBREW_BREW_GIT_REMOTE}" ]]
+then
   ohai "HOMEBREW_BREW_GIT_REMOTE is set to a non-default URL:"
   echo "${tty_underline}${HOMEBREW_BREW_GIT_REMOTE}${tty_reset} will be used for Homebrew/brew Git remote."
   non_default_repos="Homebrew/brew"
-  additional_shellenv_commands+=("export HOMEBREW_BREW_GIT_REMOTE=\"$HOMEBREW_BREW_GIT_REMOTE\"")
+  additional_shellenv_commands+=("export HOMEBREW_BREW_GIT_REMOTE=\"${HOMEBREW_BREW_GIT_REMOTE}\"")
 fi
 
-if [[ "$HOMEBREW_CORE_DEFAULT_GIT_REMOTE" != "$HOMEBREW_CORE_GIT_REMOTE" ]]; then
+if [[ "${HOMEBREW_CORE_DEFAULT_GIT_REMOTE}" != "${HOMEBREW_CORE_GIT_REMOTE}" ]]
+then
   ohai "HOMEBREW_CORE_GIT_REMOTE is set to a non-default URL:"
   echo "${tty_underline}${HOMEBREW_CORE_GIT_REMOTE}${tty_reset} will be used for Homebrew/core Git remote."
   non_default_repos="${non_default_repos:-}${non_default_repos:+ and }Homebrew/core"
-  additional_shellenv_commands+=("export HOMEBREW_CORE_GIT_REMOTE=\"$HOMEBREW_CORE_GIT_REMOTE\"")
+  additional_shellenv_commands+=("export HOMEBREW_CORE_GIT_REMOTE=\"${HOMEBREW_CORE_GIT_REMOTE}\"")
 fi
 
-if [[ -z "${NONINTERACTIVE-}" ]]; then
+if [[ -z "${NONINTERACTIVE-}" ]]
+then
   ring_bell
   wait_for_user
 fi
 
-if [[ -d "${HOMEBREW_PREFIX}" ]]; then
-  if [[ "${#chmods[@]}" -gt 0 ]]; then
+if [[ -d "${HOMEBREW_PREFIX}" ]]
+then
+  if [[ "${#chmods[@]}" -gt 0 ]]
+  then
     execute_sudo "/bin/chmod" "u+rwx" "${chmods[@]}"
   fi
-  if [[ "${#group_chmods[@]}" -gt 0 ]]; then
+  if [[ "${#group_chmods[@]}" -gt 0 ]]
+  then
     execute_sudo "/bin/chmod" "g+rwx" "${group_chmods[@]}"
   fi
-  if [[ "${#user_chmods[@]}" -gt 0 ]]; then
-    execute_sudo "/bin/chmod" "755" "${user_chmods[@]}"
+  if [[ "${#user_chmods[@]}" -gt 0 ]]
+  then
+    execute_sudo "/bin/chmod" "g-w,o-w" "${user_chmods[@]}"
   fi
-  if [[ "${#chowns[@]}" -gt 0 ]]; then
-    execute_sudo "$CHOWN" "$USER" "${chowns[@]}"
+  if [[ "${#chowns[@]}" -gt 0 ]]
+  then
+    execute_sudo "${CHOWN}" "${USER}" "${chowns[@]}"
   fi
-  if [[ "${#chgrps[@]}" -gt 0 ]]; then
-    execute_sudo "$CHGRP" "$GROUP" "${chgrps[@]}"
+  if [[ "${#chgrps[@]}" -gt 0 ]]
+  then
+    execute_sudo "${CHGRP}" "${GROUP}" "${chgrps[@]}"
   fi
 else
   execute_sudo "/bin/mkdir" "-p" "${HOMEBREW_PREFIX}"
-  if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
-    execute_sudo "$CHOWN" "root:wheel" "${HOMEBREW_PREFIX}"
+  if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+  then
+    execute_sudo "${CHOWN}" "root:wheel" "${HOMEBREW_PREFIX}"
   else
-    execute_sudo "$CHOWN" "$USER:$GROUP" "${HOMEBREW_PREFIX}"
+    execute_sudo "${CHOWN}" "${USER}:${GROUP}" "${HOMEBREW_PREFIX}"
   fi
 fi
 
-if [[ "${#mkdirs[@]}" -gt 0 ]]; then
+if [[ "${#mkdirs[@]}" -gt 0 ]]
+then
   execute_sudo "/bin/mkdir" "-p" "${mkdirs[@]}"
-  execute_sudo "/bin/chmod" "g+rwx" "${mkdirs[@]}"
-  execute_sudo "$CHOWN" "$USER" "${mkdirs[@]}"
-  execute_sudo "$CHGRP" "$GROUP" "${mkdirs[@]}"
+  execute_sudo "/bin/chmod" "u=rwx,g=rwx" "${mkdirs[@]}"
+  if [[ "${#mkdirs_user_only[@]}" -gt 0 ]]
+  then
+    execute_sudo "/bin/chmod" "g-w,o-w" "${mkdirs_user_only[@]}"
+  fi
+  execute_sudo "${CHOWN}" "${USER}" "${mkdirs[@]}"
+  execute_sudo "${CHGRP}" "${GROUP}" "${mkdirs[@]}"
 fi
 
-if ! [[ -d "${HOMEBREW_REPOSITORY}" ]]; then
+if ! [[ -d "${HOMEBREW_REPOSITORY}" ]]
+then
   execute_sudo "/bin/mkdir" "-p" "${HOMEBREW_REPOSITORY}"
 fi
-execute_sudo "$CHOWN" "-R" "$USER:$GROUP" "${HOMEBREW_REPOSITORY}"
+execute_sudo "${CHOWN}" "-R" "${USER}:${GROUP}" "${HOMEBREW_REPOSITORY}"
 
-if ! [[ -d "${HOMEBREW_CACHE}" ]]; then
-  if [[ -z "${HOMEBREW_ON_LINUX-}" ]]; then
+if ! [[ -d "${HOMEBREW_CACHE}" ]]
+then
+  if [[ -z "${HOMEBREW_ON_LINUX-}" ]]
+  then
     execute_sudo "/bin/mkdir" "-p" "${HOMEBREW_CACHE}"
   else
     execute "/bin/mkdir" "-p" "${HOMEBREW_CACHE}"
   fi
 fi
-if exists_but_not_writable "${HOMEBREW_CACHE}"; then
+if exists_but_not_writable "${HOMEBREW_CACHE}"
+then
   execute_sudo "/bin/chmod" "g+rwx" "${HOMEBREW_CACHE}"
 fi
-if file_not_owned "${HOMEBREW_CACHE}"; then
-  execute_sudo "$CHOWN" "-R" "$USER" "${HOMEBREW_CACHE}"
+if file_not_owned "${HOMEBREW_CACHE}"
+then
+  execute_sudo "${CHOWN}" "-R" "${USER}" "${HOMEBREW_CACHE}"
 fi
-if file_not_grpowned "${HOMEBREW_CACHE}"; then
-  execute_sudo "$CHGRP" "-R" "$GROUP" "${HOMEBREW_CACHE}"
+if file_not_grpowned "${HOMEBREW_CACHE}"
+then
+  execute_sudo "${CHGRP}" "-R" "${GROUP}" "${HOMEBREW_CACHE}"
 fi
-if [[ -d "${HOMEBREW_CACHE}" ]]; then
-  execute "$TOUCH" "${HOMEBREW_CACHE}/.cleaned"
+if [[ -d "${HOMEBREW_CACHE}" ]]
+then
+  execute "${TOUCH}" "${HOMEBREW_CACHE}/.cleaned"
 fi
 
-if should_install_command_line_tools && version_ge "$macos_version" "10.13"; then
+if should_install_command_line_tools && version_ge "${macos_version}" "10.13"
+then
   ohai "Searching online for the Command Line Tools"
   # This temporary file prompts the 'softwareupdate' utility to list the Command Line Tools
   clt_placeholder="/tmp/.com.apple.dt.CommandLineTools.installondemand.in-progress"
-  execute_sudo "$TOUCH" "$clt_placeholder"
+  execute_sudo "${TOUCH}" "${clt_placeholder}"
 
   clt_label_command="/usr/sbin/softwareupdate -l |
                       grep -B 1 -E 'Command Line Tools' |
@@ -619,18 +820,20 @@ if should_install_command_line_tools && version_ge "$macos_version" "10.13"; the
                       sed -e 's/^ *Label: //' -e 's/^ *//' |
                       sort -V |
                       tail -n1"
-  clt_label="$(chomp "$(/bin/bash -c "$clt_label_command")")"
+  clt_label="$(chomp "$(/bin/bash -c "${clt_label_command}")")"
 
-  if [[ -n "$clt_label" ]]; then
-    ohai "Installing $clt_label"
-    execute_sudo "/usr/sbin/softwareupdate" "-i" "$clt_label"
-    execute_sudo "/bin/rm" "-f" "$clt_placeholder"
+  if [[ -n "${clt_label}" ]]
+  then
+    ohai "Installing ${clt_label}"
+    execute_sudo "/usr/sbin/softwareupdate" "-i" "${clt_label}"
+    execute_sudo "/bin/rm" "-f" "${clt_placeholder}"
     execute_sudo "/usr/bin/xcode-select" "--switch" "/Library/Developer/CommandLineTools"
   fi
 fi
 
 # Headless install may have failed, so fallback to original 'xcode-select' method
-if should_install_command_line_tools && test -t 0; then
+if should_install_command_line_tools && test -t 0
+then
   ohai "Installing the Command Line Tools (expect a GUI popup):"
   execute_sudo "/usr/bin/xcode-select" "--install"
   echo "Press any key when the installation has completed."
@@ -638,14 +841,16 @@ if should_install_command_line_tools && test -t 0; then
   execute_sudo "/usr/bin/xcode-select" "--switch" "/Library/Developer/CommandLineTools"
 fi
 
-if [[ -z "${HOMEBREW_ON_LINUX-}" ]] && ! output="$(/usr/bin/xcrun clang 2>&1)" && [[ "$output" == *"license"* ]]; then
-  abort "$(cat <<EOABORT
+if [[ -z "${HOMEBREW_ON_LINUX-}" ]] && ! output="$(/usr/bin/xcrun clang 2>&1)" && [[ "${output}" == *"license"* ]]
+then
+  abort "$(
+    cat <<EOABORT
 You have not agreed to the Xcode license.
 Before running the installer again please agree to the license by opening
 Xcode.app or running:
     sudo xcodebuild -license
 EOABORT
-)"
+  )"
 fi
 
 ohai "Downloading and installing Homebrew..."
@@ -667,11 +872,18 @@ ohai "Downloading and installing Homebrew..."
 
   execute "git" "reset" "--hard" "origin/master"
 
-  if [[ "${HOMEBREW_REPOSITORY}" != "${HOMEBREW_PREFIX}" ]]; then
-    execute "ln" "-sf" "${HOMEBREW_REPOSITORY}/bin/brew" "${HOMEBREW_PREFIX}/bin/brew"
+  if [[ "${HOMEBREW_REPOSITORY}" != "${HOMEBREW_PREFIX}" ]]
+  then
+    if [[ "${HOMEBREW_REPOSITORY}" == "${HOMEBREW_PREFIX}/Homebrew" ]]
+    then
+      execute "ln" "-sf" "../Homebrew/bin/brew" "${HOMEBREW_PREFIX}/bin/brew"
+    else
+      abort "The Homebrew/brew repository should be placed in the Homebrew prefix directory."
+    fi
   fi
 
-  if [[ ! -d "${HOMEBREW_CORE}" ]]; then
+  if [[ ! -d "${HOMEBREW_CORE}" ]]
+  then
     ohai "Tapping homebrew/core"
     (
       execute "/bin/mkdir" "-p" "${HOMEBREW_CORE}"
@@ -692,8 +904,11 @@ ohai "Downloading and installing Homebrew..."
   execute "${HOMEBREW_PREFIX}/bin/brew" "update" "--force" "--quiet"
 ) || exit 1
 
-if [[ ":${PATH}:" != *":${HOMEBREW_PREFIX}/bin:"* ]]; then
-  warn "${HOMEBREW_PREFIX}/bin is not in your PATH."
+if [[ ":${PATH}:" != *":${HOMEBREW_PREFIX}/bin:"* ]]
+then
+  warn "${HOMEBREW_PREFIX}/bin is not in your PATH.
+  Instructions on how to configure your shell for Homebrew
+  can be found in the 'Next steps' section below."
 fi
 
 ohai "Installation successful!"
@@ -703,7 +918,8 @@ ring_bell
 
 # Use an extra newline and bold to avoid this being missed.
 ohai "Homebrew has enabled anonymous aggregate formulae and cask analytics."
-echo "$(cat <<EOS
+echo "$(
+  cat <<EOS
 ${tty_bold}Read the analytics documentation (and how to opt-out) here:
   ${tty_underline}https://docs.brew.sh/Analytics${tty_reset}
 No analytics data has been sent yet (or will be during this \`install\` run).
@@ -712,7 +928,8 @@ EOS
 "
 
 ohai "Homebrew is run entirely by unpaid volunteers. Please consider donating:"
-echo "$(cat <<EOS
+echo "$(
+  cat <<EOS
   ${tty_underline}https://github.com/Homebrew/brew#donations${tty_reset}
 EOS
 )
@@ -725,34 +942,38 @@ EOS
 ) || exit 1
 
 ohai "Next steps:"
-case "$SHELL" in
+case "${SHELL}" in
   */bash*)
-    if [[ -r "$HOME/.bash_profile" ]]; then
-      shell_profile="$HOME/.bash_profile"
+    if [[ -r "${HOME}/.bash_profile" ]]
+    then
+      shell_profile="${HOME}/.bash_profile"
     else
-      shell_profile="$HOME/.profile"
+      shell_profile="${HOME}/.profile"
     fi
     ;;
   */zsh*)
-    shell_profile="$HOME/.zprofile"
+    shell_profile="${HOME}/.zprofile"
     ;;
   *)
-    shell_profile="$HOME/.profile"
+    shell_profile="${HOME}/.profile"
     ;;
 esac
-if [[ "$UNAME_MACHINE" == "arm64" ]] || [[ -n "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ "${UNAME_MACHINE}" == "arm64" ]] || [[ -n "${HOMEBREW_ON_LINUX-}" ]]
+then
   cat <<EOS
-- Add Homebrew to your ${tty_bold}PATH${tty_reset} in ${tty_underline}${shell_profile}${tty_reset}:
+- Run these two commands in your terminal to add Homebrew to your ${tty_bold}PATH${tty_reset}:
     echo 'eval "\$(${HOMEBREW_PREFIX}/bin/brew shellenv)"' >> ${shell_profile}
     eval "\$(${HOMEBREW_PREFIX}/bin/brew shellenv)"
 EOS
 fi
-if [[ -n "${non_default_repos}" ]]; then
-  s=""
-  if [[ "${#additional_shellenv_commands[@]}" -gt 1 ]]; then
-    s="s"
+if [[ -n "${non_default_repos}" ]]
+then
+  plural=""
+  if [[ "${#additional_shellenv_commands[@]}" -gt 1 ]]
+  then
+    plural="s"
   fi
-  echo "- Add the non-default Git remote${s} for ${non_default_repos} in ${tty_underline}${shell_profile}${tty_reset}:"
+  echo "- Run these commands in your terminal to add the non-default Git remote${plural} for ${non_default_repos}:"
   printf "    echo '%s' >> ${shell_profile}\n" "${additional_shellenv_commands[@]}"
   printf "    %s\n" "${additional_shellenv_commands[@]}"
 fi
@@ -761,16 +982,21 @@ echo "- Run \`brew help\` to get started"
 echo "- Further documentation: "
 echo "    ${tty_underline}https://docs.brew.sh${tty_reset}"
 
-if [[ -n "${HOMEBREW_ON_LINUX-}" ]]; then
+if [[ -n "${HOMEBREW_ON_LINUX-}" ]]
+then
   echo "- Install the Homebrew dependencies if you have sudo access:"
 
-  if [[ $(command -v apt-get) ]]; then
+  if [[ -x "$(command -v apt-get)" ]]
+  then
     echo "    sudo apt-get install build-essential"
-  elif [[ $(command -v yum) ]]; then
+  elif [[ -x "$(command -v yum)" ]]
+  then
     echo "    sudo yum groupinstall 'Development Tools'"
-  elif [[ $(command -v pacman) ]]; then
+  elif [[ -x "$(command -v pacman)" ]]
+  then
     echo "    sudo pacman -S base-devel"
-  elif [[ $(command -v apk) ]]; then
+  elif [[ -x "$(command -v apk)" ]]
+  then
     echo "    sudo apk add build-base"
   fi
 
@@ -778,6 +1004,5 @@ if [[ -n "${HOMEBREW_ON_LINUX-}" ]]; then
     See ${tty_underline}https://docs.brew.sh/linux${tty_reset} for more information
 - We recommend that you install GCC:
     brew install gcc
-
 EOS
 fi