I'm trying to attach to a specific memory address with IPC::SharedMem, but keep getting in at 0x00000000 instead. Here's the ipcs output indicating what I specifically want to monitor:

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     stat
+us
0x00000000 98304      root       600        67108864   20         dest
0x0052e2c1 65537      postgres   600        56         5
0xf102ee77 131074     XXXXXXX    700        65535      0

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I'm trying to monitor the one whose username I have redacted, at 0xf102ee77. Here's my code for trying to do so: 
use strict;
use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR SHM_RDONLY);
use IPC::SharedMem;
use Class::Struct;

my $key = '0xf102ee77';
my $shm = IPC::SharedMem->new(${key},65535,SHM_RDONLY);
&fl_die("Could not open shared memory segment.") unless defined(${shm}
+);
my $stat = ${shm}->stat;
&fl_die("Could not stat shared memory segment.") unless defined(${stat
+});
my $concount = ${stat}->nattch;

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Here's what my actual shared memory requests are creating (even without the create flag being used): 
0x00000000 393224     root       0          65535      0
0x00000000 425993     root       0          65535      0
0x00000000 458762     root       0          65535      0
0x00000000 491531     root       0          65535      0
0x00000000 524300     root       0          65535      0
0x00000000 557069     root       0          65535      0
0x00000000 589838     root       0          65535      0

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While I get no errors, nattch keeps reading zero, largely because I'm getting in at 0x00000000 instead of the requested address. If I try unquoting the key value, it won't even attach to any shared memory, and comes back undefined at the constructor call.

May I please get some assistance on this? This is my first time needing to deal with shared memory. I know what I'm after (nattch), but this module is not the best documented in the world.

Thanks!

In reply to Using IPC::SharedMem to get nattch for a specific address? by fairlite

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