sed question...

[Gary Kline]

	My earlier post about deleting the first N lines was answered by
	this one-liner site {below}.   I wasn't including any
	redirection; doing so finally resolved the problem.  Now I need
	to delete every line from the 19th or so to the last line.
	Question one, can anybody explain the following syntax?  What do
	"P", "D" "ba" represent, in other words?


 # delete the last 10 lines of a file
 sed -e :a -e '$d;N;2,10ba' -e 'P;D'   # method 1
 sed -n -e :a -e '1,10!{P;N;D;};N;ba'  # method 2


	Question two, can sed do its thing inline?

	thanks in advance,

	gary


-- 
  Gary Kline  kline at thought.org   www.thought.org  Public Service Unix
      http://jottings.thought.org   http://transfinite.thought.org