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POHow to create a new process and communicate with that using shared memory
 

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  1. POHow to create a new process and communicate with that using shared memory
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    <p>Hi i am trying to create an application1 which takes input data "hello world". I am creating a new process using system() and I want to access data of application1 in this process using shared memory(interprocess communication). I tried to run this program but couldn't get the output "hello world". How to attach the shared memory in application1 and process1 to the same address location. please help me with this.</p> <p><strong>Application1.c</strong></p> <pre><code>#include &lt;stdio.h&gt; #include &lt;sys/shm.h&gt; #include &lt;sys/stat.h&gt; int main () { int segment_id; char* shared_memory; struct shmid_ds shmbuffer; int segment_size; const int shared_segment_size = 0x6400; /* Allocate a shared memory segment. */ segment_id = shmget (IPC_PRIVATE, shared_segment_size, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR); /* Attach the shared memory segment. */ shared_memory = (char*) shmat (segment_id, 0, 0); printf ("shared memory attached at address %p\n", shared_memory); /* Determine the segment’s size. */ shmctl (segment_id, IPC_STAT, &amp;shmbuffer); segment_size = shmbuffer.shm_segsz; printf ("segment size: %d\n", segment_size); /* Write a string to the shared memory segment. */ sprintf (shared_memory, "Hello, world."); /* Detach the shared memory segment. */ system("./process1"); shmdt (shared_memory); shmctl (segment_id, IPC_RMID, 0); return 0; } </code></pre> <p><strong>process1.c</strong></p> <pre><code>#include &lt;stdio.h&gt; #include &lt;sys/shm.h&gt; #include &lt;sys/stat.h&gt; int main () { int segment_id; char* shared_memory; struct shmid_ds shmbuffer; int segment_size; const int shared_segment_size = 0x6400; /* Allocate a shared memory segment. */ segment_id = shmget (IPC_PRIVATE, shared_segment_size, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR); /* Attach the shared memory segment. */ shared_memory = (char*) shmat (segment_id, 0, 0); printf ("shared memory2 attached at address %p\n", shared_memory); printf ("%s\n", shared_memory); /* Detach the shared memory segment. */ shmdt (shared_memory); return 0; } </code></pre> <p>output:</p> <pre><code>shared memory attached at address 0x7f616e4f2000 segment size: 25600 shared memory22 attached at address 0x7f8746d17000 </code></pre> <p>The output is not printing data in the shared memory. I want the output to print "hello, world".</p> <p>Thank you</p>
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    1. USmaddy
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      1. POHow to create a new process and communicate with that using shared memory
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    1. COWhy do you want to use shared memory as IPC. That's horribly hard work. The alternatives are orders of magnitude easier.
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      1. USDavid Heffernan
    2. COoh really. This is my first time doing program on IPC and I have to cover all IPC's that is the work assigned to me by my TL.
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