diff --git a/dup.rb b/dup.rb
index 349ea0c..9369957 100755
--- a/dup.rb
+++ b/dup.rb
@@ -115,6 +115,7 @@ def action_help
 	puts "-l, --list              Lists all available containers."
 	puts "    --host              Starts a container with net: host - which implies not using ports, networks and/or links."
 	puts "    --regenerate        Generates YAML content from a running container."
+	puts "    --all               Use all containers defined in yml files."
 	puts "-v, --verbose           More verbose output."
 	exit 1
 end
@@ -442,10 +443,12 @@ opts.each do |opt, arg|
 			action = :regenerate
 		when '--verbose'
 			$verbose = true
+		when '--all'
+			container = Dir[$base_dir + "/*.yml"].sort.map{|f| Container.new(File.basename(f, ".yml"))}
 	end
 end
 
-container = ARGV.map{|c| Container.new(c)}
+container ||= ARGV.map{|c| Container.new(c)}
 
 if needs_container
 	if container.empty?