using tr

Need to replace the first character in a string with the upper case equivalent. Not sure how to use "tr" in this case - all my attempts resulted in the whole word being converted to upper case. The first character is not fixed (will vary periodically).

Any suggestion?

Thanks

Here are some examples, but does not include tr but might be helpful.

# echo hello | nawk '{sub(".",toupper(substr($0,1,1)),$0)}{print}'
Hello