linux ipcs 共享内存

# 检查当前系统的共享内存限制
ipcs -lm

# 如果需要，可以调整限制
sudo sysctl -w kernel.shmmax=更大的值

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

int main() {
    key_t key = ftok("/tmp/shmfile", 65);
    int shmid = shmget(key, 1024, 0666 | IPC_CREAT);
    if (shmid == -1) {
        perror("shmget");
        return 1;
    }

    char *str = (char*) shmat(shmid, (void*)0, 0);
    if (str == (char*)(-1)) {
        perror("shmat");
        return 1;
    }

    printf("Attached to shared memory segment\n");
    // 进行读写操作...

    if (shmdt(str) == -1) {
        perror("shmdt");
        return 1;
    }
    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};
    semop(semid, &sb, 1); // 获取信号量

    // 安全地访问共享内存
    sprintf(str, "Hello, World!");

    sb.sem_op = 1;
    semop(semid, &sb, 1); // 释放信号量

    shmdt(str);
    return 0;
}