title: How to set file write permission
body: <p>I want to install Magento 2 on Centos 7, during installtion, file write permission error display as following:<br>
  File Permission Check</p>
  
  <p>4 file permission not met.  Hide detail  </p>
  
  <p>The best way to resolve this is to allow write permissions for files in the following Magento directories and subdirectories. The exact fix depends on your server, your host, and other system variables. 
   For help, see our File Permission Help or call your hosting provider. 
   "/var/www/html/app/etc"   - Not writable, change the permissions.
   "/var/www/html/var"   - Not writable, change the permissions. 
   "/var/www/html/pub/media"   - Not writable, change the permissions. 
   "/var/www/html/pub/static"   - Not writable, change the permissions.  </p>
  
  <p>Then I gave command via ssh:
  1. sudo chown -R apache:apache /var/www/html
  2. sudo find var vendor pub/static pub/media app/etc -type f -exec chmod u+w {} \;
  3. sudo find var vendor pub/static pub/media app/etc -type d -exec chmod u+w {} \;</p>
  
  <p>But the error is still in there, so how to give this file write permission.</p>