SED

   #!/bin/sh - 
   # rename files to lower/upper case... 
   # 
   # usage: 
   #       move-to-lower * 
   #       move-to-upper * 
   # or 
   #       move-to-lower -r . 
   #       move-to-upper -r . 
   # 
help()
{
        cat << eof
Usage: $0 [-n] [-r] [-h] files...
-n      do nothing, only see what would be done
-r      recursive (use find)
-h      this message
files   files to remap to lower case
例
       $0 -n *              (see if everything is ok, then...)
       $0 *
       $0 -r

eof
}
apply_cmd='sh'
finder='echo $* | tr " " "\n"'
files_only=
while :
do
        case "$1" in
                -n) apply_cmd='cat' ;;
                -r) finder='find $* -type f';;
                -h) help ; exit 1 ;;
                *) break ;;
        esac
        shift
done
[ "$1" ] || {
        echo Usage: $0 [-n] [-r] files...
        exit 1
}
LOWER='abcdefghijklmnopqrstuvwxyz'
UPPER='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
case `basename $0` in
        *to-lower*)
                FROM=$UPPER; TO=$LOWER ;;
        *to-upper*)
                TO=$UPPER; FROM=$LOWER ;;
        *lower*)
                FROM=$UPPER; TO=$LOWER ;;
        *upper*)
                TO=$UPPER; FROM=$LOWER ;;
        *)
                FROM=$UPPER; TO=$LOWER ;;
esac
eval $finder | sed -n '
   # remove all trailing /s 
s/\/*$//
   # add ./ if there are no path, only filename 
/\//!s/^/.\//
   # save path+filename 
h
   # remove path 
s/.*\///
   # do conversion only on filename 
y/'$FROM'/'$TO'/
   # swap, now line contains original path+file, hold space contains conv filename 
x
   # add converted file name to line, which now contains something like 
   # path/file-name\nconverted-file-name 
G
   # check if converted file name is equal to original file name, if it is, do 
   # not print nothing 
/^.*\/\(.*\)\n\1/b
   # now, transform path/fromfile\ntofile, into mv path/fromfile path/tofile 
   # and print it 
s/^\(.*\/\)\(.*\)\n\(.*\)$/mv \1\2 \1\3/p
' | $apply_cmd