How to combine consecutive numbers into ranges?

Question

Command line

Hello!
Tell me, please, with what and how can you combine the sequence of numbers
1
2
3
4
5
9
12
13
14
into the ranges
1-5,9,12-14?
It is preferable to do this in the FreeBSD CLI.

Answer 1

for you and for my own warm-up, I wrote this one-liner:
if you feed him your numbers (like you have, one number per line), then it outputs:

1-5, 9, 12-14