[post] cheating at wordle with grep (#9)

* [post] cheating at wordle with grep

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posts/2022-07-11_cheating_at_wordle_with_grep.yaml

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+date: 2022-07-11
+title: 'Cheating at Wordle with grep'
+---
+I usually try to make a good effort at
+[Wordle](https://www.nytimes.com/games/wordle/index.html), but sometimes I get
+down to the last one or two chances and need some help. Instead of anything
+fancy-pants, I usually turn to a dictionary file and my friend, `grep`.
+
+So, first thing's first, you need a dictionary file, which is just a file with
+a bunch of words one-per-line. These are usually found in `/usr/share/dict`. I
+happen to have `cracklib-small` on my machine so we'll use that.
+
+First, you'll want to get all the five-letter words out of the file. I use the
+regex `^\w{5}$`, which is `^` for the start of the line, `\w` for an
+alphanumeric character, `{5}` saying that there are 5 of them, and `$` for the
+end of the line. The beginning and end of line markers are important, otherwise
+you'll get words that contain 5 or more letters.
+
+```
+grep -E '^\w{5}$' /usr/share/dict/cracklib-small
+```
+
+At this point, I've already made some guesses and have a few letters in the
+right spot, and some letters which are correct but in the wrong spot. We'll
+bucket these into two `grep`s.
+
+For letters in the right spot, I stick those right into a regex. For example,
+let's say I know the word starts with 'f' and 'a':
+
+```
+grep -E 'fa\w\w\w'
+```
+
+For the right letters in the wrong spot, I simply use the letter as the regex.
+If I have multiple letters, I can chain those together by piping grep like so:
+
+```
+grep s | grep t
+```
+
+So chaining them all together:
+
+```
+$ grep -E '^\w{5}$' /usr/share/dict/cracklib-small \
+    | grep -e 'fa\w\w\w' \
+    | grep s | grep t
+facts
+fasts
+fates
+faust
+```
+
+You could eliminate words that have letters you've already eliminiated by
+chaining `grep -v <letter>` to the end, but I find that pretty cumbersome.
+There's only a handful of possible words at this point, so I think it's easier
+to just remove them in my head.