echo "SOME" | sed -e :a -e "s/^.\{1,$COUNT\}$/ &/;ta"


Could someone please,
tell me how does this script work?
Also, what is ":a" and what for what it's needed?

Is this command part of a script? If yes, could you post the entire script else what is $COUNT?

:a - defines a label 'a' and
ta - branches to (like goto) to label 'a' if the substitution is successful

I understand that this sed is trying to right justify the text to $count characters(provided the line length is less than $count character).