공유메모리 shmget가 말썽입니다.

#include <sys/ipc.h>
#include <sys/shm.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>

#define FILENAMELEN 10

struct data
{
char filename[FILENAMELEN];
char mtext[1024];
};

int main(int argc, char **argv)
{
int shmid = 0;
void *shared_memory;
struct data ldata;
int n, source;
char buf[1024];

if((source = open(argv[1], O_RDONLY)) < 0)
{
perror("open readfile");
exit(0);
}

shmid = shmget((key_t)1234, sizeof(ldata), 0666|IPC_CREAT);
if(shmid == -1)
{
perror("shmget");
exit(0);
}

shared_memory = shmat(shmid, (void *)0, 0);
if(shared_memory == -1)
{
perror("shmat");
exit(1);
}

sprintf(ldata.filename, "%s", argv[2]);
while((n = read(source, buf, 1024)) > 0)
{
strncpy(ldata.mtext, buf, n);
printf("%s:\n", ldata.filename);
printf("%s", ldata.mtext);

memcpy((void *)shared_memory, (void *)&ldata, sizeof(ldata));
sleep(1);
}
return 0;
}