Insert Line break for word.

string.gsub(/(.{1,#{col}})( +|$\n?)|(.{1,#{col}})/,"\\1\\3\
")

Example : str ="kkkkkkkkkkk"
str.gsub(/(.{1,#{5}})( +|$\n?)|(.{1,#{5}})/,"\\1\\3\
")

o/p:
kkkkk
kkkkk
k