find . -type f -name ‘[[:upper:]]*’
If you want to change files to all lower case, e.g. your mp3 music files then run the following script. The -i option for the mv command stands for interactive, i.e. it will prompt for your approval.
if [ $# -eq 0 ] ;
echo Usage: $0 Files exit 0
for f in $* ;
do g:`echo $f | tr "[A-Z]" "[a-z]"`
echo mv -i $f $g mv -i $f $g
Thanks to Anil Awasare for this script