msg.h, msg - message queue structures
#include <sys/msg.h>
The <sys/msg.h> header defines the following data types through typedef:
used for the number of messages in the message queue
used for the number of bytes allowed in the message queue
These types are unsigned integer types that are able to store values at least as large as a type unsigned short.
The <sys/msg.h> header defines the following constant as a message operation flag:
no error if big message
The msqid_ds structure contains the following members:
struct ipc_perm    msg_perm      Operation permission structure.
msgqnum_t          msg_qnum      Number of messages currently on 
                                 queue.
msglen_t           msg_qbytes    Maximum number of bytes allowed 
                                 on queue.
pid_t              msg_lspid     Process ID of last msgsnd(2).
pid_t              msg_lrpid     Process ID of last msgrcv(2).
time_t             msg_stime     Time of last msgsnd().
time_t             msg_rtime     Time of last msgrcv().
time_t             msg_ctime     Time of last change.
The pid_t, time_t, key_t, size_t, and ssize_t types are defined as described in <sys/types.h>. See types(3HEAD).
See attributes(5) for descriptions of the following attributes:
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msgctl(2), msgget(2), msgrcv(2), msgsnd(2), ipc.h(3HEAD), types.h(3HEAD), attributes(5), standards(5)