$ pwd
/home/pi/Documents/curate/req
$ ls
1.udplisten.pl  requires1.pm
$ perl -d 1.udplisten.pl -e '/HELLO xyZ129/'

Loading DB routines from perl5db.pl version 1.53
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(1.udplisten.pl:77):	$Getopt::Std::STANDARD_HELP_VERSION = 1;
  DB<1> b 86                                                                    
  DB<2> c                                                                       
main::(1.udplisten.pl:86):	my $RXSZ = $opts{b}//1024;
  DB<2> p $EXPR                                                                 
/HELLO xyZ129/
  DB<3> c                                                                       

192.168.red.acted
Debugged program terminated.  Use q to quit or R to restart,
use o inhibit_exit to avoid stopping after program termination,
h q, h R or h o to get additional info.
  DB<3>                                                                         

  DB<3> save 1.udp.txt                                                          
commands saved in 1.udp.txt
  DB<4> q                                                                       
$