then check /proc/$pid/cmdline ...

cmdline doesn't exist in Solaris /proc. Proc-ProcessTable does the trick on several platforms:

use strict;
use warnings;

use Proc::ProcessTable;

my $proc_table = Proc::ProcessTable->new->table;
my ($process) = grep { $_->pid == $$ } @$proc_table;

print $process->cmndline, "\n";
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