shell commands: colourize messages

Library/Homebrew/brew.sh

@@ -26,8 +26,17 @@ esac
 # Higher depths mean this command was invoked by another Homebrew command.
 export HOMEBREW_COMMAND_DEPTH=$((HOMEBREW_COMMAND_DEPTH + 1))
 
+ohai() {
+  if [[ -t 1 && -z "$HOMEBREW_NO_COLOR" ]] # check whether stdout is a tty.
+  then
+    echo -e "\\033[34m==>\\033[0m \\033[1m$*\\033[0m" # blue arrow and bold text
+  else
+    echo "==> $*"
+  fi
+}
+
 onoe() {
-  if [[ -t 2 ]] # check whether stderr is a tty.
+  if [[ -t 2 && -z "$HOMEBREW_NO_COLOR" ]] # check whether stderr is a tty.
   then
     echo -ne "\\033[4;31mError\\033[0m: " >&2 # highlight Error with underline and red color
   else

Library/Homebrew/cmd/update-reset.sh

@@ -36,11 +36,11 @@ homebrew-update-reset() {
   do
     [[ -d "$DIR/.git" ]] || continue
     cd "$DIR" || continue
-    echo "==> Fetching $DIR..."
+    ohai "Fetching $DIR..."
     git fetch --force --tags origin
     echo
 
-    echo "==> Resetting $DIR..."
+    ohai "Resetting $DIR..."
     git checkout --force -B master origin/master
     echo
   done

Library/Homebrew/cmd/vendor-install.sh

@@ -87,7 +87,7 @@ fetch() {
   temporary_path="$CACHED_LOCATION.incomplete"
 
   mkdir -p "$HOMEBREW_CACHE"
-  [[ -n "$HOMEBREW_QUIET" ]] || echo "==> Downloading $VENDOR_URL" >&2
+  [[ -n "$HOMEBREW_QUIET" ]] || ohai "Downloading $VENDOR_URL" >&2
   if [[ -f "$CACHED_LOCATION" ]]
   then
     [[ -n "$HOMEBREW_QUIET" ]] || echo "Already downloaded: $CACHED_LOCATION" >&2
@@ -107,7 +107,7 @@ fetch() {
 
     if [[ ! -f "$temporary_path" ]]
     then
-      [[ -n "$HOMEBREW_QUIET" ]] || echo "==> Downloading $VENDOR_URL2" >&2
+      [[ -n "$HOMEBREW_QUIET" ]] || ohai "Downloading $VENDOR_URL2" >&2
       "$HOMEBREW_CURL" "${curl_args[@]}" "$VENDOR_URL2" -o "$temporary_path"
     fi
 
@@ -180,7 +180,7 @@ install() {
   fi
 
   safe_cd "$VENDOR_DIR"
-  [[ -n "$HOMEBREW_QUIET" ]] || echo "==> Pouring $(basename "$VENDOR_URL")" >&2
+  [[ -n "$HOMEBREW_QUIET" ]] || ohai "Pouring $(basename "$VENDOR_URL")" >&2
   tar "$tar_args" "$CACHED_LOCATION"
   safe_cd "$VENDOR_DIR/portable-$VENDOR_NAME"