orahpatch_SID directory
Found a directory /dev/shm/orahpatch_<SID> created by 19c instances.
I see oracle executable probably creates it:
oracle@bell : strings oracle |grep orahpatch
Can not create /dev/shm/orahpatch_@/stpseg.dat
/dev/shm/orahpatch_@/stpseg.dat
It is not removed upon instance shutdown.
What is it used for?