On 3 Sep, Tim Rice wrote:
| In your message regarding Re: No match on Invalid recipient: dated Sun, 02
| Sep 2001 17:22:27 -0400 (EDT), Don Hammond said that ...
|
| [...]
|
| > FWIW, this can be done without external programs (space and tab in two
| > character classes below).
|
| Thanks, I have seen other references to perform operations without the use
| of external programs. Is this a speed concern? If a receipt calls an
| external program will all other mail queue until that mail is returned to
| procmail?
|
| In other words, what are the potential problems one should consider when
| using external programs from procmail?
Here's a couple. I'm sure others can add more.
Efficiency. Each time procmail fires up an external program, that's an
additional process. Without trying to start a flamefest, I'd say that
much of this harkens back to the days when cpu cycles and memory were a
lot more precious than they are (generally) today. Depending on your
hardware and usage (load), it may not be a pressing concern to you.
It may not even be your hardware, but then the valid justification would
be being a friendly user. The difference between Andrew's two solutions
and mine are practically negligible in most cases probably. But that's
not to say it's irrelevant. IMO, even if it's more a "game" than a
necessity to produce more efficient code, it's a virtuous one. And no,
less efficient recipes won't cause mail to be queued, unless your MTA is
configured to do so above a specified load and you breach it -- and that
would probably require a real effort towards inefficiency. A new
procmail process is spawned for each new message.
Portability. Excluding differences between versions, a pure procmail
recipe that works on one machine will work on another. There's no
guarantee that each external program you use today will be installed on
every system you might move to tomorrow. You may not think that's a
consideration, but if it does become one you'll wish you had thought
differently. In practice, since we're talking about echo and sed here,
that's probably not a big deal either. Although, differences between
usage of the "same" utilities on different systems can be significant,
so you still might be surprised.
--
/"\
Don Hammond \ / ASCII Ribbon Campaign
Raleigh, NC US X Against HTML Mail,
/ \ and News Too
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