I'm not sure about this. Vocalise:
The uuidgen(1) utility now has a -r option …
What does end of the phrase sound like, to you?
- a hyphen r option
- a dash r option
- an r option
I would probably say "an r option", which is not technically correct, but does feel natural, probably because I'm so accustomed to seeing options with hyphens (the hyphen is assumed).
Alternatively:
The uuidgen(1) utility has a new option -r …