#print
Normally the 's' command only changes
the first instance on a line of the expression
it is looking for.  Sometimes you want to change
more than one instance.  If you put a 'g' after the
command, as in
  s/cat/dog/g
all instances of 'cat' will be changed to 'dog'. To
print the result you must say
  s/cat/dog/gp
('pg' at the end doesn't work, sorry).
Edit file 'stuff' in this directory to change every
instance of 'green' to 'red' on every line.
Then rewrite the file and type "ready".
#create Ref
red light, village red
red book, red paper, red pencil
red car, red sign, redhorn
#create stuff
green light, village green
green book, green paper, green pencil
green car, green sign, greenhorn
#user
#cmp stuff Ref
#log
#next
43.1a 10
43.2a 5