messagessend

Message Send, also known as msgsnd, is a POSIX system call used in Unix-like systems to send messages to other processes. It is a low-level interface for inter-process communication (IPC) and is commonly used in system programming.

Message Send is a member of the System V IPC family of functions, which includes msgrcv to receive messages, msgctl to control messages, and msgget to create or access a message queue. The msgsnd function sends a message to a message queue. The message itself is a block of data up to a maximum length defined at message queue creation time.

When calling msgsnd, the calling process specifies the message queue identifier, the message type, and the message to be sent. The message queue identifier is returned when the message queue is created, and the message type is a unique identifier for the message within the queue.

If the message is successfully sent, msgsnd returns 0. Otherwise, it returns -1 and sets errno to indicate the error. The possible return values from msgsnd include EACCES, which indicates that the calling process does not have permissions to write to the message queue; and EAGAIN, which indicates that the message queue is full.

Message Send is used extensively in many applications, including those requiring real-time communication and message passing. It is considered a relatively low-level function and requires understanding of the underlying message queue and IPC mechanisms.

The interface for msgsnd is defined in the POSIX standard, which provides portability across different operating systems and implementations.