fix error

lib/tasks/change_site_server_name.rake

@@ -9,8 +9,8 @@ namespace :create_site do
       if !site_server.nil?
         @password = site_server.password
         Net::SSH.start(site_server.ip , site_server.account , password: site_server.password) do |ssh|
-          nginx_file_content = exec_ssh_command_by_sudo(ssh,"bash -c \"cat #{site_construct.nginx_file}\"")
-          nginx_file_content = nginx_file_content.gsub(/^[ \t]*server_name[ \t]+.*;/,"  server_name #{args.server_name};").gsub('$','\$').gsub(/^\[sudo\].*\: /,'')
+          nginx_file_content = exec_command_by_user(ssh,"cat #{site_construct.nginx_file}")
+          nginx_file_content = nginx_file_content.gsub(/^[ \t]*server_name[ \t]+.*;/,"  server_name #{args.server_name};").gsub('$','\$')
           puts nginx_file_content
           cmd = "sh -c \"echo '#{nginx_file_content}' > #{site_construct.nginx_file}\""
           exec_ssh_command_by_sudo(ssh,cmd)
@@ -22,6 +22,10 @@ namespace :create_site do
       puts [e,e.backtrace]
     end
   end
+  def exec_command_by_user(session,command)
+    output = session.exec!(command)
+    return output
+  end
   def exec_ssh_command_by_sudo(session,command)
     output = session.exec!("echo '#{@password}' | sudo -S #{command}")
     if output.include?("sudo:") && output.include?("command not found")