ipcrm - how to clear a shared memory segment which ipcrm says does not exist

If you run the following command to remove a shared memory segment and you get this error:

# ipcrm -m 65537

ipcrm: 0515-020 shmid(65537) was not found.

However, if you run the ipcs command, you still see the segment there:

# ipcs | grep 65537

m 65537 0x00000000 DCrw------- root system

If you look carefully, you will notice the "D" in the forth column. The "D" means:

D If the associated shared memory segment has been removed. It disappears when the last process attached to the segment detaches it.

So, to clear the shared memory segment, find the process which is still associated with the segment:

# ps -ef | grep process_owner

where process_owner is the name of the owner using the shared segment

Now kill the process found from the ps command above

# kill -9 pid

Running another ipcs command will show the shared memory segment no longer exists:

# ipcs | grep 65537