bin/optimize-png in geordi-0.15.2 vs bin/optimize-png in geordi-0.15.3

@@ -1,7 +1,6 @@
 #!/usr/bin/env ruby
-require "ruby-debug"
 require 'fileutils'
 
 # pngcrush -rem allb -reduce -brute original.png optimized.png
 # pngcrush -d target-dir/ *.png
 #
@@ -36,13 +35,16 @@
   indented_puts "=" *script_name.size
   indented_puts "- Removes color profiles: cHRM, sRGB, gAMA, ICC, etc."
   indented_puts "- Eliminates unused colors and reduce bit-depth (If possible)"
   indented_puts "- May reduce PNG file size lossless"
   indented_puts
-  indented_puts "Batch optimize all *.png in current directory:"
+  indented_puts "Batch-optimize all *.png in a directory:"
   indented_puts "  #{script_name} directory"
   indented_puts
+  indented_puts "Batch-optimize the current directory:"
+  indented_puts "  #{script_name} ."
+  indented_puts
   indented_puts "Optimize single file:"
   indented_puts "  #{script_name} input.png"
   indented_puts
 end
 
@@ -89,19 +91,24 @@
     optimize_inplace(png_relative_path)
   end
 end
 
 def main
-  if ARGV.size == 1
+  if `which pngcrush`.strip == ""
+    indented_puts
+    indented_puts "You have to install pngcrush first: sudo apt-get install pngcrush"
+    indented_puts
+  elsif ARGV.size == 1
     path = ARGV[0]
     if File.directory?(path)
       batch_optimize_inplace(path)
     elsif File.file?(path)
       optimize_inplace(path)
+    else
+      print_manual
+      indented_puts "*** Error: '#{path}' is neither a directory nor a file ***"
+      indented_puts
     end
-    print_manual
-    indented_puts "*** Error: '#{path}' is neither a directory nor a file ***"
-    indented_puts
   else
     print_manual
   end
 end