Fix `brew style` shellcheck warnings.

Library/Homebrew/brew.sh

@@ -26,7 +26,7 @@ export HOMEBREW_COMMAND_DEPTH=$((HOMEBREW_COMMAND_DEPTH + 1))
 onoe() {
   if [[ -t 2 ]] # check whether stderr is a tty.
   then
-    echo -ne "\033[4;31mError\033[0m: " >&2 # highlight Error with underline and red color
+    echo -ne "\\033[4;31mError\\033[0m: " >&2 # highlight Error with underline and red color
   else
     echo -n "Error: " >&2
   fi
@@ -90,6 +90,9 @@ then
 
   # The system Curl is too old for some modern HTTPS certificates on
   # older macOS versions.
+  #
+  # Intentionally set this variable by exploding another.
+  # shellcheck disable=SC2086,SC2183
   printf -v HOMEBREW_MACOS_VERSION_NUMERIC "%02d%02d%02d" ${HOMEBREW_MACOS_VERSION//./ }
   if [[ "$HOMEBREW_MACOS_VERSION_NUMERIC" -lt "101000" ]]
   then
@@ -162,6 +165,7 @@ export HOMEBREW_CACHE
 export HOMEBREW_CELLAR
 export HOMEBREW_SYSTEM
 export HOMEBREW_CURL
+export HOMEBREW_SYSTEM_CURL_TOO_OLD
 export HOMEBREW_GIT
 export HOMEBREW_PROCESSOR
 export HOMEBREW_PRODUCT
@@ -340,8 +344,8 @@ access to all bottles."
 EOS
 fi
 
-# Hide shellcheck complaint:
-# shellcheck source=/dev/null
+# Don't need shellcheck to follow this `source`.
+# shellcheck disable=SC1090
 source "$HOMEBREW_LIBRARY/Homebrew/utils/analytics.sh"
 setup-analytics
 
@@ -401,13 +405,13 @@ then
   # a Ruby script and avoids hard-to-debug issues if the Bash script is updated
   # at the same time as being run.
   #
-  # Hide shellcheck complaint:
-  # shellcheck source=/dev/null
+  # Don't need shellcheck to follow this `source`.
+  # shellcheck disable=SC1090
   source "$HOMEBREW_BASH_COMMAND"
   { update-preinstall; "homebrew-$HOMEBREW_COMMAND" "$@"; exit $?; }
 else
-  # Hide shellcheck complaint:
-  # shellcheck source=/dev/null
+  # Don't need shellcheck to follow this `source`.
+  # shellcheck disable=SC1090
   source "$HOMEBREW_LIBRARY/Homebrew/utils/ruby.sh"
   setup-ruby-path
 

Library/Homebrew/cmd/update-reset.sh

@@ -26,12 +26,12 @@ homebrew-update-reset() {
     set -x
   fi
 
-  if [[ -z "$REPOS" ]]
+  if [[ -z "${REPOS[]}" ]]
   then
     REPOS+=("$HOMEBREW_REPOSITORY" "$HOMEBREW_LIBRARY"/Taps/*/*)
   fi
 
-  for DIR in ${REPOS[@]}
+  for DIR in "${REPOS[@]}"
   do
     [[ -d "$DIR/.git" ]] || continue
     cd "$DIR" || continue

Library/Homebrew/cmd/update.sh

@@ -8,8 +8,8 @@
 #:    If `--force` (or `-f`) is specified then always do a slower, full update check even
 #:    if unnecessary.
 
-# Hide shellcheck complaint:
-# shellcheck source=/dev/null
+# Don't need shellcheck to follow this `source`.
+# shellcheck disable=SC1090
 source "$HOMEBREW_LIBRARY/Homebrew/utils/lock.sh"
 
 # Replaces the function in Library/Homebrew/brew.sh to cache the Git executable to

Library/Homebrew/cmd/vendor-install.sh

@@ -2,13 +2,16 @@
 #:  * `vendor-install` [<target>]:
 #:     Install vendor version of Homebrew dependencies.
 
-# Hide shellcheck complaint:
-# shellcheck source=/dev/null
+# Don't need shellcheck to follow this `source`.
+# shellcheck disable=SC1090
 source "$HOMEBREW_LIBRARY/Homebrew/utils/lock.sh"
 
 VENDOR_DIR="$HOMEBREW_LIBRARY/Homebrew/vendor"
 
 # Built from https://github.com/Homebrew/homebrew-portable-ruby.
+#
+# Dynamic variables can't be detected by shellcheck
+# shellcheck disable=SC2034
 if [[ -n "$HOMEBREW_MACOS" ]]
 then
   if [[ "$HOMEBREW_PROCESSOR" = "Intel" ]]
@@ -152,7 +155,6 @@ EOS
 
 install() {
   local tar_args
-  local verb
 
   if [[ -n "$HOMEBREW_VERBOSE" ]]
   then
@@ -168,13 +170,7 @@ install() {
 
   if [[ -d "$VENDOR_VERSION" ]]
   then
-    verb="reinstall"
     mv "$VENDOR_VERSION" "$VENDOR_VERSION.reinstall"
-  elif [[ -n "$(ls -A .)" ]]
-  then
-    verb="upgrade"
-  else
-    verb="install"
   fi
 
   safe_cd "$VENDOR_DIR"
@@ -185,8 +181,6 @@ install() {
   if quiet_stderr "./$VENDOR_VERSION/bin/$VENDOR_NAME" --version >/dev/null
   then
     ln -sfn "$VENDOR_VERSION" current
-    # remove old vendor installations by sorting files with modified time.
-    ls -t | grep -Ev "^(current|$VENDOR_VERSION)" | tail -n +4 | xargs rm -rf
     if [[ -d "$VENDOR_VERSION.reinstall" ]]
     then
       rm -rf "$VENDOR_VERSION.reinstall"
@@ -197,7 +191,7 @@ install() {
     then
       mv "$VENDOR_VERSION.reinstall" "$VENDOR_VERSION"
     fi
-    odie "Failed to $verb vendor $VENDOR_NAME."
+    odie "Failed to vendor $VENDOR_NAME $VENDOR_VERSION."
   fi
 
   trap - SIGINT

Library/Homebrew/utils/analytics.sh

 # Migrate analytics UUID to its new home in Homebrew repo's git config and
 # remove the legacy UUID file if detected.
 migrate-legacy-uuid-file() {
-  local legacy_uuid_file="$HOME/.homebrew_analytics_user_uuid"
+  local legacy_uuid_file analytics_uuid
+
+  legacy_uuid_file="$HOME/.homebrew_analytics_user_uuid"
+
   if [[ -f "$legacy_uuid_file" ]]
   then
-    local analytics_uuid="$(<"$legacy_uuid_file")"
+    analytics_uuid="$(<"$legacy_uuid_file")"
     if [[ -n "$analytics_uuid" ]]
     then
       git config --file="$HOMEBREW_REPOSITORY/.git/config" --replace-all homebrew.analyticsuuid "$analytics_uuid" 2>/dev/null
@@ -23,8 +26,9 @@ setup-analytics() {
     return
   fi
 
-  local message_seen="$(git config --file="$git_config_file" --get homebrew.analyticsmessage 2>/dev/null)"
-  local analytics_disabled="$(git config --file="$git_config_file" --get homebrew.analyticsdisabled 2>/dev/null)"
+  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" ]]
   then
     # Internal variable for brew's use, to differentiate from user-supplied setting

bin/brew

@@ -8,12 +8,13 @@ if ! [[ -d "$PWD" ]]; then
 fi
 
 quiet_cd() {
-  cd "$@" >/dev/null
+  cd "$@" >/dev/null || return
 }
 
 symlink_target_directory() {
-  local target="$(readlink "$1")"
-  local target_dirname="$(dirname "$target")"
+  local target target_dirname
+  target="$(readlink "$1")"
+  target_dirname="$(dirname "$target")"
   local directory="$2"
   quiet_cd "$directory" && quiet_cd "$target_dirname" && pwd -P
 }
@@ -83,5 +84,7 @@ then
 
   exec /usr/bin/env -i "${FILTERED_ENV[@]}" /bin/bash "$HOMEBREW_LIBRARY/Homebrew/brew.sh" "$@"
 else
+  # Don't need shellcheck to follow this `source`.
+  # shellcheck disable=SC1090
   source "$HOMEBREW_LIBRARY/Homebrew/brew.sh"
 fi