It is possible.
use strict;
use warnings;

sub foo{
    my $a = 1;
    print "$a\n";
    bar(\$a);
    print "$a\n";
}

sub bar{
    my $b = shift;
    $$b = 2;
}

foo;

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In reply to Re: passing arguments as reference by lidden
in thread passing arguments as reference by Anonymous Monk

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