Drush allow to download and install drupal core, drupal modules and drupal themes.
Note : It is recommended to use composer to manage drupal 8, modules and themes.
Download a file via SCP
File :Â Â Â Â Â Â /tmp/mysql.dump.sql
Server/Login :Â Â Â THE_USERNAME:PASSWORD@domain.com
Download to : Â Â Â . (Current directory) scp user:pass@domain.com:/tmp/mysql.dump.sql .
Note : It's not possible to read the current headers. You could make another request to the same URL and read its headers, but there is no guarantee that the headers are exactly equal to the current.