Is awk available?  This worked for me, but it's not on Plan9.  It does copy the newline after the 2nd "ABC" (I wasn't sure if leading or all blank lines should be deleted).
$ cat a.data
 dflkdl dlkrwo3je4ogjmdmxd
ABC asassadfasdf asdfasdf asdfasdf CBA hhhhhhhhhhjjjjjjjjjjioioioi
sodifs
sdfsd
ABC
dasdfas aasdfa
njnjn CBA
fkpri34ouijglkrlptgf;c
$ awk 'BEGIN {RS = "ABC"; FS = "CBA"}NR == 1 {next}{print $1}' a.data
 asassadfasdf asdfasdf asdfasdf

dasdfas aasdfa
njnjn

On Fri, Oct 24, 2008 at 3:04 PM, Rudolf Sykora <rudolf.sykora@gmail.com> wrote:
> doesn't s/ABC(the_interesting_part)CBA/x/g work for you?
> maybe i don't understand the example.  if so, could you explain?
>
> - erik

I think not.
I have a file say like this

ABC asassadfasdf asdfasdf asdfasdf CBA hhhhhhhhhhjjjjjjjjjjioioioi
sodifs
sdfsd
ABC
dasdfas aasdfa
njnjn CBA

and I want to get

' asassadfasdf asdfasdf asdfasdf '
'dasdfas aasdfa'
'njnjn'

where I added apostrophes to see the spaces on indivial lines. Simply:
give me everything that is between delimiters (ABC and CBA).

Ruda