Shell script for extracting unique directories from a file containing urls line by line

unique_directories.sh

#!/bin/sh

# Inspired from https://twitter.com/rez0__
# Usage ./unique_directories.sh urls.txt 

rm unique_urls.txt > /dev/null
cat $1 | rev | cut -d/ -f2- | rev | sort -u | anew unique_urls.txt > /dev/null
for i in {1..10}; do cat unique_urls.txt | rev | cut -d/ -f2- | rev | sort -u | anew unique_urls.txt > /dev/null; done

sed -i "" "s/$/\//g" unique_urls.txt
sed -i "" "/^\/$/d" unique_urls.txt
sed -e "/\/\/$/d" unique_urls.txt | grep -Ev "(:/|://)$" | sort -u