Gary Stainburn wrote:
>
> Hi all,
Hello,
> I've got a project where I need to develop an single-board-computer based
> network device using packet modems connected to Amateur Radio equipment and
> I'm trying to develop a simulator in Perl under Linux and I've got a few
> questions.
>
> Basically I'm going to have X number of nodes running inside Xterm sessions,
> all sitting in the same working directory and simulating transmitting data by
> appending the data to a file. Each program will simulate receiving the data,
> by doing the equivelent of a tail -f on this file.
>
> Keyboard input will be used to simulate data being received from the box's
> serial port.
>
> 1) How can I simulate the 'tail -f' under perl without hanging my program.
perldoc -q "tail -f"
Have you thought about writting to a FIFO (named pipe) instead of
appending to a file?
man perlipc
man mkfifo
> If I pseudo code it it may give a better idea of what I mean.
>
> // in main code
>
> if ($command=&getcommand()) {
> &do_something($command);
> }
>
> sub getcommand() {
> if character available
> add character to buffer
> if character = end.of.packet
> return buffer
> else
> return false
> }
>
> 2) can this same method be used to get the characters from the keyboard.
Perl has a curses module that may help with this and #4
man Curses
> 3) can I reduce the priority of these programs (equivelent of the unix 'nice'
> command) from within the perl script or do I need to do it from the shell
> script calling the program. (If I nice -> xterm -> perl script, will the nice
> still affect the perl script or will I have to do xterm -> nice -> perl
> script)?
The owner of a process can lower its priority but it can't raise it.
system "renice +2 $$";
> 4) Is there an easy way (or a hard way) within Perl to control the xterm
> output, something similar to GotoXY that I used to have in TurboPascal in the
> good old (?) DOS days.
John
--
use Perl;
program
fulfillment
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