Linux Shell Piping w/Shared Memory Post: 302991488

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Top Forums Programming Linux Shell Piping w/Shared Memory Post 302991488 by jim mcnamara on Saturday 11th of February 2017 08:14:01 AM

02-11-2017

Registered User

Welcome the the UNIX forums.

You do not use pipes with shared memory, necessarily. You are reading and writing in memory to your own process memory, part of which is shared among processes. So each child process is reading and writing it's own memory, too.

What you are talking about is IPC. Interprocess communication. Pipes are one method, shared memory segments are another. Pipes use physical files on disk, shared memory transfers data between processes using a segment of memory both processes 'own' and can read and usually write.

You need to do some reading, the help you need is beyond the scope of these forums.
If you get stuck we can help. This tutorial is written in an offhand conversational way, most people enjoy reading it.

Beej's Guide to Unix IPC

More formal:
6 Linux Interprocess Communications

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LEARN ABOUT POSIX

ipcmk

IPCMK(1)							   User Commands							  IPCMK(1)

NAME

       ipcmk - make various IPC resources

SYNOPSIS

       ipcmk [options]

DESCRIPTION

       ipcmk allows you to create shared memory segments, message queues, and semaphore arrays.

OPTIONS

       Resources can be specified with these options:

       -M, --shmem size
	      Create  a  shared  memory  segment of size bytes.  The size argument may be followed by the multiplicative suffixes KiB (=1024), MiB
	      (=1024*1024), and so on for GiB, etc. (the "iB" is optional, e.g., "K" has the same meaning as "KiB") or the suffixes KB (=1000), MB
	      (=1000*1000), and so on for GB, etc.

       -Q, --queue
	      Create a message queue.

       -S, --semaphore number
	      Create a semaphore array with number of elements.

       Other options are:

       -p, --mode mode
	      Access permissions for the resource.  Default is 0644.

       -V, --version
	      Display version information and exit.

       -h, --help
	      Display help text and exit.

SEE ALSO

       ipcrm(1), ipcs(1)

AUTHOR

       Hayden A. James <hayden.james@gmail.com>

AVAILABILITY

       The  ipcmk  command  is	part  of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils
       /util-linux/>.

util-linux							     July 2014								  IPCMK(1)