Shell – find the set of common files between several directories

When you say the files "names include a common word," I am assuming that you are referring to the fact that they share the .cc extension: if so, using Gilles' answer here you could construct a command that would achieve your goal:

 find -type f -exec sh -c '
    for file; do [ "${file##*.}" = "cc" ] && 
    mv -- "$file" "${file%.cc}.ccp"; done
    ' -- {} +

See this answer on SO for more detail

You don't need to use awk at all. Use the built-in tests that ksh provides, something like this:

#!/bin/ksh

for NAME in *
do
    FOUND=no
    if [[ -d $NAME && $NAME != '.' && $NAME != '..' ]]
    then
        for SUBNAME in $NAME/*
        do
            if [[ -d $SUBNAME ]]
            then
                FOUND=yes
                break
            fi
        done
        if [[ $FOUND == no ]]
        then
            echo Found only files in $NAME
        fi
    fi
done

That little script looks in all the directories in the current directory, and tells you if they only contain files, no sub-directories.