Comment by bugen

Thank you for using pypipe!

  How about?  
  
  cat staff.xml | ppp xpath -O path='./Animal/Age'

I also wanted to allow custom commands like this, but I decided on the current format for a few reasons, including the ability to omit the default 'line' command from the arguments. For frequently used commands, please consider setting up aliases in your configuration files (e.g ~/.profile).

  alias xpath='ppp custom -N xpath'