Re: how to match against first N lines/bytes of body?

Adam Grove asked,

| When I have recipes search for patterns in the body of a message,
| I'd like to limit how many lines (or bytes, it doesn't really
| matter much) into the message the search is performed.
| That is, I'd like every match appearing after some line N, for 
| a value of N I specify, to just be ignored. 
| 
| Does anyone have a (hopefully efficient) way of doing this?

If N had been small, say 6 as in a previous thread about this, I'd
suggest this, which allows for up to five (6 - 1) previous lines;
leave out the last ".*" just before "pattern" if the pattern is
left-anchored:

  :0B
  * ^^(.*$(.*$(.*$(.*$(.*$)?)?)?)?)?.*pattern
  whatever

or something like that; I actually answered

  :0B
  * ^^(.*$)?(.*$)?(.*$)?(.*$)?(.*$)?.*pattern
  whatever

at the time but someone who knows procmail's innards better than I said
that the nested version, while harder to type, is more efficient.  One
could also do this if N=6:

  :0B
  * ^^(.*$)?(.*$)?(.*$.*$.*$)?.*pattern
  whatever

or

  :0B
  * ^^(.*$)?(.*$.*$)?(.*$.*$)?.*pattern
  whatever

But if N=50, to heck with it:

  :0Bi
  toplines=| head -$N # sed ${N}q if you don't have head

  :0a
  * toplines ?? pattern
  whatever

There were some other methods, but they could run into LINEBUF trouble,
so I won't bring them up again.