use warnings;
use strict;

my $ppid = getppid();

open (my $cmdfh, '<', "/proc/$ppid/cmdline") or die "Unable to open ppid cmdline: $!";

my $cmdline = <$cmdfh>;
close $cmdfh;

if ($cmdline =~ /bash|ksh|csh/) {
    print "Started by a shell\n";
}
elsif ($cmdline =~ /perl/) {
    print "Perl is the daddy\n";
}
else {
    print "I was created by: $cmdline\n";
}