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 
concatenate files and print on the standard output
 
Concatenate FILE(s), or standard input, to standard output.

With no FILE, or when FILE is -, read standard input.
 
-E, --show-ends
       display $ at end of each line
source manpages: cat