Shmget: Invalid argument. Why i get this error?

最新推荐文章于 2019-10-25 17:17:36 发布

转载最新推荐文章于 2019-10-25 17:17:36 发布 · 1.3k 阅读

linux错误专栏收录该内容

20 篇文章

订阅专栏

本文解决了一个关于使用POSIX共享内存接口时出现的“shmget: Invalid argument”错误的问题。通过引用manual page中的相关信息，指出问题可能源于尝试创建的共享内存段大小与已存在的段不匹配。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Question：

I get a "shmget: Invalid argument error" while i try to execute this part of code

  int *nFS, *spb, *cell1, shmid;
  key_t key = 5768; 

  //i need a shared memory segment in which i can put 3 ints
  if ((shmid = shmget(key, (sizeof(int) * 3), IPC_CREAT | 0666)) < 0 ) {
             perror("shmget");
             exit(1);
       } 
 if ((spb = (int)shmat(shmid, NULL, 0))== -1 ){  
            perror("shmat");
            exit(1);
      }
  cell1= spb + 1 ;
  nFS= cell1 + 1;
  //i try to assign here 7 to  nFS
  *nFS=7;

there is something wrong here but i can't figure out what. Can you help me?

Answer：

From the shmget(1) man page:

EINVAL A new segment was to be created and size < SHMMIN or size > SHMMAX, or no new segment was to be created, a segment with given key existed, but size is greater than the size of that segment.

You should check whether you still have an segment for this key using ipcs and remove it with ipcrm.