In what ways can processes communicate?
UNIX processes on their own are boring; they are interesting when they communicate. There are many methods of “Inter-process communication”, or IPC. What are all these methods? There are many!:
- Files:
open,close,read,write. The sender writes to a file; the receiver reads from it. USP: durability. - Pipes:
pipe,close,read,write. A pipe, created withpipe, is a byte queue.pipereturns file descriptors for both ends. Closing both ends destroys the pipe. - Signals:
sigaction,kill. The sender can send a signal to the receiver. A signal does not have associated data. - Socket:
socket,bind-listen-accept/connect,close,read,write. Sockets link processes over network interfaces. USP: connecting remote processes (not just local ones). - Message queues:
mq_open,mq_timedreceive,mq_timedsend. A message queue is a bit like a pipe, but with a proper concept of messages (a message is a byte array). - Semaphores:
semget,semop. Used to protect common resources used by processes. - Shared memory:
shmgetand friends. A single memory location can be read/written by multiple processes. USP: communication via memory, not system calls.
Tagged . All content copyright James Fisher 2017. This post is not associated with my employer.
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