semaphore shmget（）semflg = 384是做什么的？

Question

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

key_t key = IPC_PRIVATE; 
int id; 
int semflg = 384; 

id = shmget(key, 8192, semflg); 

有人能告诉我什么影响3844在semflg的价值？

Answer 1

shmget的的手册页说：

除了上述标志， shmflg的至少显著9位指定授予所有者，组和 其他用户的权限。这些位具有相同的格式，并且与open（2）的mode参数 具有相同的含义。

因此，让我们检查的开放手册页：

The following symbolic constants are provided for mode: 
- S_IRWXU 00700 user (file owner) has read, write, and execute permission 
- S_IRUSR 00400 user has read permission 
- S_IWUSR 00200 user has write permission 
- S_IXUSR 00100 user has execute permission 
- S_IRWXG 00070 group has read, write, and execute permission 
- S_IRGRP 00040 group has read permission 
- S_IWGRP 00020 group has write permission 
- S_IXGRP 00010 group has execute permission 
- S_IRWXO 00007 others have read, write, and execute permission 
- S_IROTH 00004 others have read permission 
- S_IWOTH 00002 others have write permission 
- S_IXOTH 00001 others have execute permission 

整数值编码为二进制1.1亿，对应于标志，即S_IRUSR|S_IWUSR ：

• 用户h作为写权限
• 用户具有读取权限

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谁写这段代码幸免2分钟他的生命，浪费更多的其他许多人的生命的时候，包括我在内。

恭喜。 :)

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编辑：感谢@Fabio图拉蒂您指出了一个重大错误;）