一开始是
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 root dest
0x4405004b gyf
ipcrm -M 0x4405004b 后变成
------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 root dest
0x00000000 gyf dest
原因，还有进程占用着该共享内存，必须关闭该进程才会彻底清除