Find all lines in a file with words longer than 4 characters, assuming that words are separated by spaces except at the begining or end of line

Code for Find all lines in a file with words longer than 4 characters, assuming that words are separated by spaces except at the begining or end of line in Unix / Linux / Ubuntu

echo Enter filename
read filename
grep -v ^[[:space:]] $filename | grep -v [[:space:]]$ | grep '.....'