$$, $PROCESS_ID, $PID- The process number of the current script / program / executable.

The process number of the current script / program / executable. Natively Perl provieds the $$ variable, but if you load the English module you can also use the $PROCESS_ID or the $PID variable names for the same thing.

See also Forking, Process ID, Parent Process ID, init

examples/process_id.pl

use strict;
use warnings;

use English qw( -no_match_vars );

print "$$\n";
print "$PROCESS_ID\n";
print "$PID\n";

1228561
1228561
1228561

perldoc