Exercise answers:

egrep "\<C\>" ideas.txt

egrep "^ACT|^Scene" hamlet.txt

egrep "\^_?\^" chat.txt

egrep "[ABCDF][+\-]?" 143.txt
more restrictive:
egrep "[ABCDF]([ +\-]|$)" 143.txt

egrep "[0-9]{3}-[0-9]{3}-[0-9]{4}" faculty.html

sed -r "s#([0-9]{3})-([0-9]{3})-([0-9]{4})#(\1) \2.\3#g" facnames.txt


#!/bin/bash

YEAR=2010
for FILE in `cat files.txt`; do
        sed -r "s#([0-9]{1,2})/([0-9]{1,2})#\1/\2/$YEAR#g" $FILE
done