Perl print "$("

Question

I'm just starting to learn Perl, and I (accidentally) came across this print behavior I can't explain. If I do:

print "$(";

the result I get is:

1000 4 20 24 25 27 29 30 44 46 117 1000 1001

Answer 1

That is known as a Special Variable. From perldoc perlvar:

$REAL_GROUP_ID
$GID
$(

The real gid of this process. If you are on a machine that supports membership in multiple groups simultaneously, gives a space separated list of groups you are in. The first number is the one returned by getgid(), and the subsequent ones by getgroups(), one of which may be the same as the first number.

etc.