#print
Suppose you wanted to match all letters and
punctuation marks.  You could try
 [^ ]
which is "anything but blank".
Try the following commands:

ed cut
1p
1s/p[^ ]/xxx/p
w
q
ready
#create Ref
stop this comxxxter
#create cut
stop this computer
#user
#cmp cut Ref
#log
#next
34.2f 5