I’m going to keep adding a number of one liners here. Mainly for my own personal usage.

Find duplicate filenames with different extensions

find . -type f -print | rev | cut -f 2- -d '.' | rev | sort | uniq -d

Mail War

Randomly spams someones with number of domains and random user.
This particular guy mark.silberman78@gmail.com thought i needed some extra mail.  I sent some back 😉

export de1=fio.ie
export de2=feeditout.com
export de3=feeditout.com

while true; 
  do export rand=$((1 + RANDOM % 3)); 
  export var=de$rand; 
  echo "fuck off with your spam" | mailx -r `tr -dc A-Za-z0-9 </dev/urandom | head -c 10`@$(eval echo \$$var) -s "fuck you, stop spamming my email address" mark.silberman78@gmail.com; 
  sleep 1; 
done