[RndTbl] interesting unix pipe problem (stop whole pipe chain on first match)

Trevor Cordes trevor at tecnopolis.ca
Sun May 31 22:19:49 CDT 2020

On 2020-05-31 Adam Thompson wrote:
> arping(8) solution:

Ya, I figured there would be other networky ways to do it.  But I
purposely was trying to use ICMP rather than arp, for the exact
opposite reason you stated: I prefer braindead or firewalled/hidden
hosts to not count in my scan.

If you forget about the network aspect of the problem, though, surely
there must be an easier way to stop a "producer" program earlier in the
pipe once you get the output you're looking for?  Would seem like a
common-ish problem if your producer is long-running and not listening
for the proper signals?

Ignoring the network aspect, no one knows a better way?  Maybe I need
to write a little something for moreutils!  Or maybe head could be
tweaked to do the work? ... guess it wouldn't know who is the start of
the pipe if it's >2 ps's...

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