Communication Methods Between processes

# Pipe: a pipe is a half-duplex communication method. data can only flow in one direction and can only be used between unrelated processes. The kinship of a process usually refers to the parent-child process relationship.
# Named pipe: A famous pipe is also a half-duplex communication method, but it allows communication between unrelated processes.
# Semophore: a semaphore is a counter that can be used to control access to shared resources by multiple processes. It is often used as a lock mechanism to prevent other processes from accessing a shared resource. Therefore, it is mainly used for synchronization between processes and between different threads in the same process.
# Message queue: a message queue is a linked list of messages stored in the kernel and identified by the message queue identifier. The message queue has overcome the disadvantages of few signal transmission information, the pipeline can only carry unformatted byte streams, and the limited buffer size.
# Signal: a signal is a complex communication method used to notify the receiving process that an event has occurred.
# Shared memory: the shared memory is the memory mapped to a segment that can be accessed by other processes. The shared memory is created by one process, but can be accessed by multiple processes. Shared memory is the fastest IPC method. It is specially designed for the low efficiency of communication between other processes. It is often used with other communication mechanisms, such as signal two, to achieve synchronization and communication between processes.
# Socket: the socket is also a mechanism for inter-process communication. Different from other communication mechanisms, it can be used for different and inter-process communication.