UNIX for Dummies Questions & Answers

Hi!
I use an and grep to play Scrabble and other word games because it helps me practice regexes, or, as my friends would say, because I'm a cheater.
Anyway, I'm trying to work out how to write a regex that might do what I want, so let's see if I can explain it properly. Let's say we want to play down. We have a letter, F, followed by three spaces, then a D, which is at the end of the board. The space below the F is a DW, so we want to play it, if possible. We have plenty of room above the F, but we can only play two spaces below F if we can't use the D, three if we can use the D. I have attached a screen-shot of the board if you're having a hard time visualizing it. I have already played "famed."
So, here's the regex I tried:

Code:

an -w -m3 -d twl 'qreraumfd' |grep -E '.*f.{1,3}d?$'

We anagram my rack, plus the F and D, and pipe it to grep. Here we're saying we can have one to three characters after the F, and the D can be there or not. While it returns many usable results, it also returns results which ignore the D. For instance:

Code:

fard
farm
fear

which can't be used because you'd have "fardd" or "farmd", and so on.
Perhaps you are thinking, "Why not just ignore the four-letter words it returns?" And certainly I could pipe it to grep one more time to eliminate them, but I want to know if I can do it all in one grep ERE.
I've tried it a few different ways, but can't quite work it out:

Code:

an -w -m3 -d twl 'qreraumfd' |grep -E '.*f.{1,2}.?d?$'

returns identical results.
What do you think? Is it possible?

As you said, you can have "f" and two letters following, or, "f" and three letters and "d".
Why not use two ored regexs: grep -E ".*f.{1,2}|.*f.{3}d"?

Aha! Yes, it works if you "cap off" the ends with a $

Code:

grep -E ".*f.{1,2}$|.*f.{3}d$"

I forgot you could do that. I was trying to figure out a way to do it with a lookaround somehow. Thanks!

Anchoring them at line end is a good idea - I had no chance to test it so missed that...
Try also the "abbreviated" pattern ".*f(.{1,2}|.{3}d)$"