On Wed, 9 Aug 2006, Lars Ellenberg wrote: > / 2006-08-09 14:45:16 +0100 > \ David Lee: > > So I think we're agreed on the principle of rewriting it. > > > > But since my earlier email a further thought has crossed my mind about the > > merits of: > > thing1 >> fifo > > thing2 >> fifo > > thing3 >> fifo > > vs: > > (thing1; thing2l thing3) >> fifo > > > > The first does three sets of open/close operations, the second does > > only one. Efficiency. > > > > Also each operation may have potential "end-of-data" or "flush" semantics > > on the fifo, whereas the second does all these as a single set. > > right. see also my other mail.
Yes. Thanks. (Our emails crossed in the post!) > > > This is probably not sigificant. But if it is (or if there is a future > > chance of its becoming significant) then the second version (the single > > parenthesised subshell into a single call to the fifo) may be preferable. > > > > I'll prepare a local-workspace patch for the: > > (thing1; thing2l thing3) >> fifo > > variant and apply it post-2.0.7 shipment. > > the original version semantics would probably best be matched by using a > second cat again, like this: > (echo ">>>"; cat -; echo "<<<") | cat - >> $HA_FIFO Hmmm... I don't see any functional difference between my proposed: (echo ">>>"; cat -; echo "<<<") >> $HA_FIFO and your proposed: (echo ">>>"; cat -; echo "<<<") | cat - >> $HA_FIFO Under what conditions would they behave differently? What benefit does your more complex version have that mine lacks? (I'm happy to learn!) Best wishes. -- : David Lee I.T. Service : : Senior Systems Programmer Computer Centre : : Durham University : : http://www.dur.ac.uk/t.d.lee/ South Road : : Durham DH1 3LE : : Phone: +44 191 334 2752 U.K. : _______________________________________________________ Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev Home Page: http://linux-ha.org/
