Fix to raise specific error when ssh user is not provided and root is used as default user.

lib/train/extras/command_wrapper.rb

@@ -162,16 +162,16 @@ class CommandWrapper
     include_options WindowsCommand
 
     def self.load(transport, options)
-      if transport.os.unix?
+      if transport.platform.unix?
         return nil unless LinuxCommand.active?(options)
         res = LinuxCommand.new(transport, options)
         verification_res = res.verify
         if verification_res
           msg, reason = verification_res
-          raise Train::UserError.new("Sudo failed: #{msg}", reason)
+          raise Train::UserError, "Sudo failed: #{msg}", reason
         end
         res
-      elsif transport.os.windows?
+      elsif transport.platform.windows?
         res = WindowsCommand.new(transport, options)
         res
       end

lib/train/platforms/detect/helpers/os_common.rb

@@ -31,6 +31,12 @@ def unix_file_exist?(path)
 
     def command_output(cmd)
       res = @backend.run_command(cmd).stdout
+      # When you try to execute command using ssh connction as root user and you have provided ssh user identity file
+      # it gives standard output to login as authorised user other than root. To show this standard ouput as an error
+      # to user we are matching the string of stdout and raising the error here so that user gets exact information.
+      if @backend.class.to_s == "Train::Transports::SSH::Connection" && res =~ /Please login as the user/
+        raise Train::UserError, "SSH failed: #{res}"
+      end
       res.strip! unless res.nil?
       res
     end