The cleanipc command is used to clear the shared memeory occupied by the SAP system. Mostly, this command is used (by <sid>adm user) while restarting an SAP system. So, you stop the system using stopsap, run the cleanipc command to clear the memory and then start the system using startsap.
Command: cleanipc <instance_nr> remove
However, sometimes, cleanipc fails to cleanup some semaphores saying: Semaphore Key: XX remove failed **** - errno = 1 (Not owner)
Command: cleanipc 06 remove
In this case, login as root and run the following commands:
ipcs –s | grep “the number from the semaphore”
ipcrm –s “the number from the above command”
The above command ipcrm clears up the semaphore which was not cleared by cleanipc command when executed by <sid>adm user. Now, if you run cleanipc again using <sid>adm, you will find that the affected semaphore is now cleared.