To change uppercase to lowercase using TR, use the command:
tr '[:upper:]' '[:lower:]' < input.txt > output.txt

Note: I found this solution online at 
http://www.cyberciti.biz/faq/linux-unix-shell-programming-converting-lowercase-uppercase/

Mark Lewis

To change uppercase to lowercase using awk, use the command:
awk '{ print tolower($0) }' input.txt > output.txt

Note: I found this solution online at 
http://linuxcommando.blogspot.com/2008/05/how-to-convert-text-files-to-all-upper.html

Lee Gatchell