Separate letters and replace whitespaces

Shell Programming and Scripting
1

Input file:

aaaa bbb dd.
qqq wwww e.

Output file:

a a a a <s> b b b <s> d d .
q q q <s> w w w w <s> e .

Can I use sed to do so in one step?

2 
awk  '{for(i=1;i<=NF;i++) printf "%s ",$i; print ""}' FS="" infile
a a a a   b b b   d d .
q q q   w w w w   e .
3

Thanks!
But how can I also add <s> in the previously existing spaces?

4 
awk  '{a="";for(i=1;i<=NF;i++) a=a sprintf("%s ",$i);gsub(/   /," <s> ",a);print a}' FS=""
a a a a <s> b b b <s> d d .
q q q <s> w w w w <s> e .

I thought the <s> was representing space, but this fix it.

5 
sed 's/./& /g; s/[[:blank:]]\{2,\}/ <s> /g'

Without an extra space at the end:

sed 's/./& /g; s/[[:blank:]]\{2,\}/ <s> /g; s/ $//'
6

Based on MadeInGermany sed you can tweak my regex some :slight_smile:
Did forget the nice &

awk '{gsub(/./,"& ");gsub(/   /," <s> ")}1'

If you like to remove the extra space added after final letter . in all example above add $1=$1

awk  '{gsub(/./,"& ");gsub(/   /," <s> ");$1=$1}1'