Remove duplicates from zsh_history

remove_dups_zsh_history.sh

# Remove duplicates from zsh_history:

$ cat -n .zsh_history | sort -t ';' -uk2 | sort -nk1 | cut -f2- > .zsh_no_duplicates_history
$ mv .zsh_no_duplicates_history .zsh_history

# In case of failure (i.e, `sort: Illegal byte sequence`), debug
# replacing the command above with `head`:

$ head -n 10000 .zsh_history | sort -t ';' -uk2 | sort -nk1 | cut -f2- 

# Replace the number above in a binary search style until 
# you find the culprit; then, remove the line and proceed.