plan9-cat.1 %2Fhome%2Fmarcos%2FEvidencias%2FBulk_20170518%2Fdomain_histogram.txt %7C grep -Eo %22%28http%7Chttps%7Cwww%29%3A%2F%2F%5Ba-zA-Z0-9.%2F%3F%3D_-%5D*%22 %7C sort %7C uniq 
catenate files
source manpages: plan9-cat