This stuff is a complete mess in APR. The name-based shmget method
*does* use and create a real file, but it's redundant AFAICT;
It's not completely redundunt AFAIU.
The shmkey param passed to shmget is calculated using ftok(). On some platforms ftok() fails if file does not exists.
But yes thats the only use of file.
Interesting . Why APR stores/read this value from file ? Isn't shmctl is better (fast?)all it does is store the size of the segment, which shmctl will tell you anyway on.
than file - (open/read/close) sequence ?
