How can I insert a blank character after each character?

    sed 's/./& /g'

Example:

    $ echo "testing" | sed 's/./& /g'
    t e s t i n g

For more examples of sed 1-liners, see [http://www.student.northpark.edu/pemente/sed/sed1line.txt sed 1-liners] or [http://sed.sourceforge.net/sedfaq.html the sed FAQ].