Bash script to solve the NYT Spelling Bee

spellingBee.sh

#!/bin/bash

dictPath="/usr/share/dict/words"

middleLetter=$1
allLetters=$2

# The following argument validations must be true in order for the script to be correct
[[ -n "$middleLetter" && -n "$allLetters " ]] || { echo "Usage: ./spellingBee.sh <middle letter> <all letters>"; exit 0; }
[[ "$middleLetter" =~ ^[a-zA-z]$ ]] || { echo "Usage: Middle letter must be a single letter"; exit 0; }
[[ "$allLetters" =~ ^[a-zA-z]+$ ]] || { echo "Usage: Arguments must contain only letters"; exit 0; }

# First, filter to words that definitely contain the middle letter.
# Then, using extended grep syntax, filter to words containing only the allowed letters.
function validWordsCommand() {
  middleLetter=$1
  allLetters=$2
  command="cat $dictPath | grep -i $middleLetter | grep -Ei '^[${allLetters}]+$' | less"
  echo $command
}

# Find the pangram by adding greps at the end to make sure the word contains all of the letters.
# All seven letters should be passed as a single string argument.
function pangramCommand() {
  letters=$1
  lettersSeparate=$(echo $letters | grep -o .)
  command="cat $dictPath | grep -Ei '^[${letters}]+$' "
  for l in $lettersSeparate; do
    command="${command} | grep -i $l"
  done
  echo $command
}

# Assemble the commands and print the output, with the pangram(s) at the end.
validWords=$(validWordsCommand $middleLetter $allLetters)
pangram=$(pangramCommand $allLetters)
{ eval $validWords; eval $pangram; } | less