items.sh: repair style

Library/Homebrew/items.sh

@@ -5,16 +5,20 @@ homebrew-items() {
   local sed_filter=$2
   local grep_filter=$3
 
-  if [[ -n "$HOMEBREW_MACOS" ]]; then
+  # HOMEBREW_MACOS is set by brew.sh
+  # shellcheck disable=SC2154
+  if [[ -n "${HOMEBREW_MACOS}" ]]; then
     sed_extended_regex_flag="-E"
   else
     sed_extended_regex_flag="-r"
   fi
 
+  # HOMEBREW_REPOSITORY is set by brew.sh
+  # shellcheck disable=SC2154
   items="$( \
-    find "$HOMEBREW_REPOSITORY/Library/Taps" \
+    find "${HOMEBREW_REPOSITORY}/Library/Taps" \
          -type d \( \
-           -name "$find_filter" -o \
+           -name "${find_filter}" -o \
            -name cmd -o \
            -name .github -o \
            -name lib -o \
@@ -22,14 +26,14 @@ homebrew-items() {
            -name vendor \
           \) \
          -prune -false -o -name '*\.rb' | \
-    sed "$sed_extended_regex_flag" \
+    sed "${sed_extended_regex_flag}" \
       -e 's/\.rb//g' \
       -e 's_.*/Taps/(.*)/(home|linux)brew-_\1/_' \
-      -e "$sed_filter" \
+      -e "${sed_filter}" \
   )"
   local shortnames
-  shortnames="$(echo "$items" | cut -d "/" -f 3)"
-  echo -e "$items\n$shortnames" | \
-    grep -v "$grep_filter" | \
+  shortnames="$(echo "${items}" | cut -d "/" -f 3)"
+  echo -e "${items}\n${shortnames}" | \
+    grep -v "${grep_filter}" | \
     sort -uf
 }