To change the permissions of a shared memory object.
POSIX shared memory is supported since Linux 2.4 and glibc 2.2.
POSIX shared memory objects have kernel persistence:
a shared memory object will exist until the system is shut down,
or until all processes have unmapped the object and it has been deleted with
Programs using the POSIX shared memory API must be compiled with
to link against the real-time library,
Accessing shared memory objects via the file system
On Linux, shared memory objects are created in a
virtual file system, normally mounted under
Since kernel 2.6.19, Linux supports the use of access control lists (ACLs)
to control the permissions of objects in the virtual file system.
Typically, processes must synchronize their access to a shared
memory object, using, for example, POSIX semaphores.
System V shared memory
etc.) is an older semaphore API.
POSIX shared memory provides a simpler, and better designed interface;
on the other hand POSIX shared memory is somewhat less widely available
(especially on older systems) than System V shared memory.