alterna.sh

#!/bin/bash
#Name of each dictionary
SP="spanish"
BR="british-english"
AM="american-english"
error (){
echo
echo "This script will search for all the words written alternating the first set of characters with the second one."
echo
echo "Two arguments needed. One for each set. Do just write all the chars together and separate each group with a space."
echo "You can select the searching dictionary, use the third argument to  write the name as you find in /usr/share/dict/"
echo "Shortnames for: -sp = spanish, -br=british-english, -am=american-english"
echo "Example: ./alterna qwertasdfgzxcvb yuiophjklñnm br"
echo "Example: ./alterna aoeiupyqjkx aoeiupyqjkx"
echo "Writting -p as first argument will print the grep expression, but don't eval it"
echo
exit
}

if [ "$1" = "-p" ]; then
 PRINT=1
 shift
else
 PRINT=0
fi

if [ -z "$2" ]; then
 error
fi
if [ -z "$1" ]; then
 error
fi

#Filters those words that start with the 2nd group and are followed by the 1st
#and finally are optionally followed by the 2nd again (so we get even and odd words). And the same starting on the first group.
GREP="grep -E '^((([$2][$1])+[$2]?)|(([$1][$2])+[$1]?))$'"

#Here is where all the dictionaries are stored
DICTURL=" /usr/share/dict/"
#Spanish dictionarie selected by default
DICT=$SP

#Also is possible to search within the british and american dictionaries
#choosing them in the third argument by writting 'br' or 'am'
if [ -z "$3" ]; then
 DICT=$SP
else
 if [ "$3" = "-br" ]; then
  DICT=$BR
 else
  if [ "$3" = "-am" ]; then
   DICT=$AM
  else
   if [ "$3" = "-sp" ]; then
    DICT=$SP
   else
    DICT=$3
   fi
  fi
 fi
fi

GREP="$GREP$DICTURL$DICT"
if [ $PRINT = 1 ]; then
 echo $GREP
else
eval $GREP
fi