linux 多进程共享内存实例

#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>

int main() {
    key_t key = ftok("/tmp/shmfile", 65); // 生成一个唯一的key
    int shmid = shmget(key, 1024, 0666|IPC_CREAT); // 创建共享内存段
    char *str = (char*) shmat(shmid, (void*)0, 0); // 将共享内存连接到当前进程的地址空间

    printf("Write Data: ");
    fgets(str, 1024, stdin); // 写入数据到共享内存

    shmdt(str); // 分离共享内存段
    return 0;
}

#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    int shmid = shmget(key, 1024, 0666|IPC_CREAT);
    char *str = (char*) shmat(shmid, (void*)0, 0);

    printf("Data read from memory: %s\n", str); // 从共享内存读取数据

    shmdt(str);
    shmctl(shmid, IPC_RMID, NULL); // 删除共享内存段
    return 0;
}

#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <stdio.h>

union semun {
    int val;
    struct semid_ds *buf;
    unsigned short *array;
};

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    int shmid = shmget(key, 1024, 0666|IPC_CREAT);
    char *str = (char*) shmat(shmid, (void*)0, 0);

    key_t semkey = ftok("/tmp/shmfile", 66);
    int semid = semget(semkey, 1, 0666|IPC_CREAT);
    union semun arg;
    arg.val = 1;
    semctl(semid, 0, SETVAL, arg);

    struct sembuf sb = {0, -1, SEM_UNDO}; // 请求资源
    semop(semid, &sb, 1);

    printf("Write Data: ");
    fgets(str, 1024, stdin);

    sb.sem_op = 1; // 释放资源
    semop(semid, &sb, 1);

    shmdt(str);
    return 0;
}