Other Alias
shmatLIBRARY
Lb libcSYNOPSIS
In sys/types.h In sys/ipc.h In sys/shm.h Ft void * Fn shmat int shmid const void *addr int flag Ft int Fn shmdt const void *addrDESCRIPTION
The Fn shmat system call attaches the shared memory segment identified by Fa shmid to the calling process's address space. The address where the segment is attached is determined as follows:- If Fa addr is 0, the segment is attached at an address selected by the kernel.
- If Fa addr is nonzero and SHM_RND is not specified in Fa flag , the segment is attached the specified address.
- If Fa addr is specified and SHM_RND is specified, Fa addr is rounded down to the nearest multiple of SHMLBA.
The Fn shmdt system call detaches the shared memory segment at the address specified by Fa addr from the calling process's address space.
RETURN VALUES
Upon success, Fn shmat returns the address where the segment is attached; otherwise, -1 is returned and errno is set to indicate the error.Rv -std shmdt
ERRORS
The Fn shmat system call will fail if:- Bq Er EINVAL
- No shared memory segment was found corresponding to Fa shmid .
- Bq Er EINVAL
- The Fa addr argument was not an acceptable address.
The Fn shmdt system call will fail if:
- Bq Er EINVAL
- The Fa addr argument does not point to a shared memory segment.