Advanced `uniq` with “unique part regex”

Question

uniq is a tool that enables once to filter lines in a file such that only unique lines are shown. uniq has some support to specify when two lines a

Answer 1

You can do this with just grep and sort

DATAFILE=file.dat

for match in $(grep -P '(!\w+!)' -o "$DATAFILE" | sort -u); do 
  grep -m1 "$match" "$DATAFILE";
done

Outputs:

foo!bar!baz
!baz!quix