Archive for the ‘perl’ Category

Using Device::Hue

Sunday, June 11th, 2023

So, I found a major lack of documentation for Device::Hue, and chatGPT had some information that I would describe as whimsically wrong.

Here’s what I ended up doing to get a working perl setup controlling my hue lights:

1) Put a valid URL in /etc/environment for the key HUE_BRIDGE
2) Put a key in /etc/environment for the key HUE_KEY
3) The following code sets lights 17 and 19 to red:


my $bridge = Device::Hue->new();
$bridge->config();
foreach $light_id (17, 19) {
my $light = $bridge->light($light_id);

$light->set_state( { hue => 0, sat => 254 });
$light->commit();
}

IPC::Shareable sets SIGCHLD to Ignore (I’ll take “Annoying undocumented side effects” for $200, Alex)

Sunday, January 1st, 2023

Just a heads up that hopefully google will index and save someone else from the several hours of digging I’ve just had to do. the perl module IPC::Shareable sets SIG{CHLD} to ignore any time you include it. You can set it back to the default behavior, but until you do, waitpid() is going to return -1 and $? will contain -1 for any pid-waiting you do.

Perl bluetooth communications

Friday, May 20th, 2022

I had a couple of notes on using Net::Bluetooth from a raspberry pi to talk to a Bluetooth serial port because I couldn’t get the example code given with Net::Bluetooth to work.

The following will connect to a mac address and send and receive data from it (in this particular example, a ESP32):


#!/usr/bin/perl

use Net::Bluetooth;
use Data::Dumper;
use IO::Handle;
my $obj = Net::Bluetooth->newsocket(“RFCOMM”);

$addr = ‘C4:4F:33:58:B6:FB’;
$port = 1;

if($obj->connect($addr, $port) != 0) {
die “connect error: $!\n”;
}

my $fh = $obj->perlfh();
$fh->autoflush(1);

sleep(1);

print “sending \n”;

print $fh “V\n”;
print “receiving\n”;

$buf = readline($fh);
print “Fetchhost: $buf\n”;

Perl arg parser

Monday, June 10th, 2013


I use this a lot when writing a simple perl script that I want to take args like –flag and –database=this and –comment=”This is a comment with spaces”

while($arg = shift) {

if(($s1,$s2) = $arg =~ /–(.*)=(.*)/) {
$l1 = lc $s1;
$s2 = $a if(($a) = $s2 =~ /^\”(.*)\”$/);
$arg{$l1} = $s2;
} elsif(($s1) = $arg =~ /–(.*)/) {
$l1 = lc $s1;
$arg{$l1} = 1;
}
}

Stick it in the top of the script, and you can then just use

if($arg{‘flag’}) {

}

$comment = $arg{‘comment’};

and so on and so forth.