🚀 go-pugleaf

How about

  (tr 'X\012' '\377X';echo '')
  | sed 's/XPROMPTX<X>X/X/g'
  | tr '\377X' 'X\012' | sed -n \$\!p

The echo '' to add a blank line and sed -n \$\!p  to take it away
are necessary because sed can't handle input without a terminating
newline. The above commands will delete any three lines with exactly
PROMPT, <, and >; I don't remember if that was the original question
but this solution is much easier to generalize than the others given,
not to mention faster.

As usual, since we're dealing with sed, if your original input does not
end with a newline then the last line will disappear. If you're worried
about this, take away the sed -n \$\!p; then normal inputs will have an
extra line on the end and no-newline last lines will not be munched.

Of course, both tr and sed will munch nulls, and any 255's will be
changed to X's.

---Dan Bernstein, bernsten@phoenix.princeton.edu