Linux-interprocess communication-shared memory

One, shared memory

Shared memory is the most efficient way to communicate, because there is no need for a process to be copied to the kernel and another process to read in the kernel.

Second, ipcs-m View shared memory

Ipcrm-m Deleting shared memory

Three, the main function

Shmget Create

Shmctl Delete

Shmat Hook up

SHMDT Cancel Hook up

Man function Name View * * * *

Iv. implementation of the Code

Comm.h

1 #pragma once 2 #include <stdio.h> 3 #include <stdlib.h> 4 #include <unistd.h> 5 #include <sys/ipc.h  > 6 #include <sys/shm.h> 7 #define _PATH_ "." 8 #define _PROJID_ 0x666 9 #define _SHM_SIZE_ 4096 int getshmget (); one int destoryshm (int shm_id); char* at_shm (int shm_id); int Delete_shm (char *addr);

Comm.c

  1  #include "comm.h"   2 int getshmget ()   3 {  4      key_t key=ftok (_path_,_projid_);  5   6      int shmflg=ipc_creat |0666;  7     int  shm_id=shmget (KEY,_SHM_SIZE_,SHMFLG);   8     if (shm_id<0)    9     { 10         perror (" Shmget "); 11         return -1; 12      }    13     return shm_id; 14 } &NBSP;&NBSP;&NBSP;&NBSP;15&NBSP;&NBSP;16&NBSP;INT&NBSP;DESTORYSHM (int shm_id)  17 { 18      return shmctl (shm_id,ipc_rmid,null); 19 }     20  21 char* at_SHM (int shm_id)  22 { 23     return  (char*) Shmat (Shm_id,null, 0);  24 } 25 int delete_shm (CHAR&NBSP;*ADDR)  26 { 27    &NBSP;&NBSP;RETURN&NBSP;SHMDT (addr);  28 }

Client.c

1 #include "comm.h" 2 int main () 3 {4 int shm_id=getshmget ();  5 char *addr=at_shm (shm_id);  6 int i=0;     7 for (; i<_shm_size_;i++) 8 {9 addr[i]= ' A '; addr[i+1]= ' + '; sleep (1); 12} Delete_shm (addr); return 0; 15}

Server.c

1 #include "comm.h" 2 int main () 3 {4 int shm_id=getshmget ();  5 char * ADDR=AT_SHM (SHM_ID);  6 int i=0; 7 for (; i<_shm_size_;i++) 8 {9 printf ("%s\n", addr), sleep (1), one} and Delete_shm (a DDR); DESTORYSHM (shm_id); return 0; 15}

Run results

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Linux-interprocess communication-shared memory