date: 2022-07-11
title: 'Cheating at Wordle with grep'
tags:
    - linux
---
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.