Prints all lines that only contains the given letters.

scrabble.sh

#!/bin/bash
# Prints all lines that only contains the given letters.
# Matching is case insensitive.
#
# usage: scrabble.sh FILE ABC

DICTIONARY_FILE=$1
CHARS_TO_USE=`echo $2 | tr '[a-z]' '[A-Z]'`
ALPHABET="ABCDEFGHIJKLMNOPQRSTUVXYZ"
FORBIDDEN_CHARS=`echo ${ALPHABET//[$CHARS_TO_USE]/}`

echo $CHARS_TO_USE

cat $DICTIONARY_FILE | 
while read a; do

  CANDIDATE_WORD=`echo $a | tr '[a-z]' '[A-Z]'`

  valid=true

  for (( i=0; i<${#FORBIDDEN_CHARS}; i++ )); do

    char=${FORBIDDEN_CHARS:$i:1}

    if [[ $CANDIDATE_WORD == *$char* ]]
    then
      valid=false
      break
    fi

  done

  if $valid
  then
    echo $CANDIDATE_WORD
  fi

done