mapping Xml File in Magento 2

I am trying to map xml file in magento 2 while working on new module declaration through this command bin/magento dev:urn-catalog:generate .idea/misc.xml the directory is (through pwd command) /opt/lampp/htdocs/magento at first it shows me this error cache_dir “/opt/lampp/htdocs/magento/var/cache/” is not writable So I have launched this command chmod -R -v 777 var/cache It shows me…