The <sys/ipc.h> header is used by three mechanisms for interprocess communication (IPC): messages, semaphores, and shared memory. All use a common structure type, ipc_perm, to pass information used in determining permission to perform an IPC operation.
The ipc_perm structure contains the following members:
uid_t uid /* owner's user ID */ gid_t gid /* owner's group ID */ uid_t cuid /* creator's user ID */ gid_t cgid /* creator's group ID */ mode_t mode /* read/write permission
The uid_t, gid_t, mode_t, and key_t types are defined as described in <sys/types.h>. See types.h(3HEAD).
Definitions are provided for the constants listed below.
IPC_CREAT Create entry if key does not exist.
IPC_EXCL Fail if key exists.
IPC_NOWAIT Error if request must wait.
IPC_PRIVATE Private key.
IPC_RMID Remove identifier.
IPC_SET Set options.
IPC_STAT Get options.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
ftok(3C), types.h(3HEAD), attributes(5), standards(5)