doing some suggestions.

lib/hammer_cli_foreman/ssh.rb

@@ -12,7 +12,9 @@ class Command < HammerCLIForeman::Command
 
     command_name 'SSH to hosts'
     option %w(-c --command), 'COMMAND', _('Command to execute'), :attribute_name => :command, :required => true
-    option %w(-n --concurrent), 'CONCURRENCY', _('Number of concurrent SSH sessions'), :attribute_name => :concurrent
+    option %w(-n --concurrent), 'CONCURRENCY', _('Number of concurrent SSH sessions'), :attribute_name => :concurrent do |o|
+      Integer(o)
+    end
     option %w(-u --user), 'USER', _('Execute as user'), :attribute_name => :user, :default => ENV['USER']
     option %w(-s --search), 'FILTER', _('Filter hosts based on a filter'), :attribute_name => :search
     option '--[no-]dns', :flag, _('Use DNS to resolve IP addresses'), :attribute_name => :use_dns
@@ -29,10 +31,7 @@ def request_params
     end
 
     def execute
-      if concurrent && concurrent.to_i == 0
-        warn _("specify 1 or more concurrent hosts")
-        return HammerCLI::EX_OK
-      end
+      signal_usage_error(_("specify 1 or more concurrent hosts")) if (!concurrent.nil? && concurrent < 1)
 
       limit = concurrent.nil? ? concurrent : concurrent.to_i
 
@@ -48,7 +47,7 @@ def execute
       ssh_options[:keys] = [identity_file] unless identity_file.to_s.empty?
 
       Net::SSH::Multi.start(:concurrent_connections => limit, :on_error => :warn) do |session|
-        puts _("executing on #{limit} concurrent host(s)") if limit.to_i > 0
+        logger.info(_("executing on #{limit} concurrent host(s)")) if limit.to_i > 0
         targets.each { |s| session.use s, ssh_options }
         session.exec command
         session.loop