topic Re: Examining Shared Memory in Operating System - HP-UX

Examining Shared Memory

OldSchool — Wed, 30 Nov 2005 16:24:10 GMT

Is there a way, short of writing my own program, to examine the "contents" of a shared memory segment.

I can see the segment with ipcs, but need to examine the data values

TIA

Scott

Re: Examining Shared Memory

A. Clay Stephenson — Wed, 30 Nov 2005 16:42:55 GMT

Get a copy of this utility:

ftp://hprc.external.hp.com/sysadmin/programs/shminfo/

Re: Examining Shared Memory

A. Clay Stephenson — Wed, 30 Nov 2005 16:44:43 GMT

This link will probably work better since it includes the 9unsupp8 password.

ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/

Re: Examining Shared Memory

Bill Hassell — Wed, 30 Nov 2005 21:35:05 GMT

shminfo will show you the addresses of all the shared memory segments, but to actually display the contents of a segment, you'll need a program. As you might expect, there are pieces of information needed (from the program creating the segment) to allow access and to prevent unauthorized access from casual users.

Re: Examining Shared Memory

A. Clay Stephenson — Wed, 30 Nov 2005 22:23:29 GMT

Bear in mind that another approach to actually examining shmem is using Perl. The functions shmget, shmctl, shmread, and shmwrite are all available --- which is rather amazing for a scripting language. One of the obvious problems with a utility that reads shared memory is that the data really only has meaning for its intended application. The data generally are non-textual. One approach would be to use shmread to read the entire contents of a shared memory segment and write it to a file. You would then use a standard utility like od to examine the file.

The other obvious "gotcha" is that shared memory segments created with IPC_PRIVATE will not be accessible by unrelated processes.

Re: Examining Shared Memory

OldSchool — Thu, 01 Dec 2005 10:14:19 GMT

Thanks for all of the quick responses. Looks like perl might be the way to go.

Scott