how to see size of directory on command line?

 Du v1.5 - report directory disk usage utility : Provides summary of disk usage at top directory tree

example command: >du -l 1 y:\

other options see: http://www.tecmint.com/check-linux-disk-usage-of-files-and-directories/

https://technet.microsoft.com/en-us/sysinternals/du.aspx