void reader(int seq) {
cout << "reader " << seq << endl;
int shm_id = shmget(SHM_KEY, BUF_SIZE, IPC_CREAT);
if (shm_id == -1) {
perror("Fail to get shared memory id");
return;
// Attach to the segment to get a pointer to it.
char* shm_buf = static_cast
(shmat(shm_id, NULL, 0));
if (shm_buf == nullptr) {
perror("Fail to attach shared memory");
return;
/* Transfer blocks of data from shared memory to stdout*/
while (1) {
cout << "buf[" << seq << "] = " << shm_buf << endl;
if (string(shm_buf) == to_string(seq)) {
break;
sleep(3);
cout << "Detaching shared memory" << endl;
if (shmdt(shm_buf) == -1) {
perror("Fail to detaching shared memory");
return;
void writer() {
int shm_id = shmget(SHM_KEY, BUF_SIZE, IPC_CREAT);
if (shm_id == -1) {
perror("Fail to get shared memory id");
return;
// Attach to the segment to get a pointer to it.
char* shm_buf = static_cast(shmat(shm_id, NULL, 0));
if (shm_buf == nullptr) {
perror("Fail to attach shared memory");
return;
/* Transfer blocks of data from shared memory to stdout*/
while (1) {
cin >> shm_buf;
cout << "Detaching shared memory" << endl;
if (shmdt(shm_buf) == -1) {
perror("Fail to detaching shared memory");
return;
int main(int argc, char* argv[]) {
if (argc < 2) {
return 0;
srand(::time(nullptr));
cout << argv[1] << endl;
string argv1 = argv[1];
if (argv1 == "reader") {
reader(rand() % 1000);
} else {
writer();
return 0;
将文件命名为shm_test.cpp，编译后运行
./shm_test reader
./shm_test writer
可以看到读者能够读取到写者写入的数据
如果报错显示
Fail to get shared memory id: Permission denied
sudo ./shm_test reader
sudo ./shm_test writer
