install: make search output more intuitive.

Closes Homebrew/homebrew#42222.
Closes Homebrew/homebrew#44892.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Library/Homebrew/cmd/install.rb

@@ -98,10 +98,36 @@ module Homebrew
       else
         ofail e.message
         query = query_regexp(e.name)
-        ohai "Searching formulae..."
-        puts_columns(search_formulae(query))
+
+        ohai "Searching for similarly named formulae..."
+        formulae_search_results = search_formulae(query)
+        case formulae_search_results.length
+        when 0
+          ofail "No similarly named formulae found."
+        when 1
+          puts "This similarly named formula was found:"
+          puts_columns(formulae_search_results)
+          puts "To install it, run:\n  brew install #{formulae_search_results.first}"
+        else
+          puts "These similarly named formulae were found:"
+          puts_columns(formulae_search_results)
+          puts "To install one of them, run (for example):\n  brew install #{formulae_search_results.first}"
+        end
+
         ohai "Searching taps..."
-        puts_columns(search_taps(query))
+        taps_search_results = search_taps(query)
+        case taps_search_results.length
+        when 0
+          ofail "No formulae found in taps."
+        when 1
+          puts "This formula was found in a tap:"
+          puts_columns(taps_search_results)
+          puts "To install it, run:\n  brew install #{taps_search_results.first}"
+        else
+          puts "These formulae were found in taps:"
+          puts_columns(taps_search_results)
+          puts "To install one of them, run (for example):\n  brew install #{taps_search_results.first}"
+        end
 
         # If they haven't updated in 48 hours (172800 seconds), that
         # might explain the error

Library/Homebrew/exceptions.rb

@@ -47,7 +47,7 @@ class FormulaUnavailableError < RuntimeError
   end
 
   def to_s
-    "No available formula for #{name} #{dependent_s}"
+    "No available formula with the name \"#{name}\" #{dependent_s}"
   end
 end