Working off serial port

[Michael Fowler]

On Wed, Jan 12, 2000 at 01:58:36PM -0900, Kevin Creason wrote:
> Because of crank calls to Emergency, we want to log PBX activity. I've got
> a unix machine nearby... heh heh. So I thinks, what better way to capture
> and parse the data from it's gobblety gook than to use Perl?

This may not be as well-suited to Perl as you would initially think.  The
gobblety-gook, I assume, is a stream of bits, and while Perl can handle
streams of bits (with pack and unpack), it can get a little awkward.  You
may want to consider C or C++.  Considering the fact that you're dealing
with a serial device (which will probably involve ioctl() invocations), Perl
may be even less well-suited.  While Perl does have ioctl(), many ioctl()
calls involve C data structures, which can be a little messy to deal with.


> Two big problems:
> 1. It's got to run all the time, even when no-one is logged in

Easy enough, just have it fork itself then have the parent exit.  There is a
set procedure for this, involving a pair of forks and a setsid() call to
truly daemonize, but this should be sufficient to allow it to run
indefinately.


> 2. How do you get info off the hardware in Perl?

Usually the same way you'd do it in C.  Opening the serial device
(/dev/ttyS[0-1] on Linux, I don't know about HP-UX.  Perl also has ioctl(). 
If worst comes to worst, you can write a module for Perl in C.


> The actual OS is HPUX, not linux. :(
> 
> AND that's another issue: how do you configure the port to be the right
> config? (1200/7/E/1) I'm not sure how to do that under linux, either.

In Linux, setserial is used for this I believe.  I have no idea how to do it
with HP-UX, possibly through ioctl()'s.  A good way of figuring it out is to
find a program that talks to a modem (such as minicom), and looking at the
source.


Michael
--
There isn't a mome rath alive that can outgrabe me.
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