You could do it with tr like so


        substr($word, 0, 1) =~ tr/a-z/A-Z/;     # first char only
        substr($word, 0, 5) =~ tr/a-z/A-Z/;     # first five chars

or with sed

        substr($word, 0, 1) =~ s/(.*)/\U$1/;    # first char only
        substr($word, 0, 5) =~ s/(.*)/\U$1/;    # first five chars
        $word =~ s/(.)/\U$1/;                   # first char
        $word =~ s/(.{5})/\U$1/;                # first five chars

or

        $word = "\u$word";                      # first char


	perl -pe 's/./\u$&/'