1. Inter-Process Communication Pipes Moti Geva geva.biu@gmail.com
Operating Systems
Inter-Process Communication
Pipes
Moti Geva

2. Inter-Process Communiacation (IPC)
IPCs are mechanisms used to communicate between processes
There are various kinds of IPC
Files
Pipes
Signals
System V IPC
Shared memory
Semaphore
Message queues
Sockets

3. (Anonymous) Pipes A kernel memory buffer No I/O involved.
Limited capacity.
Blocks on
Read: Empty pipe.
Write: Full pipe.
Unidirectional data channel.
One fd for reading and one for writing.

4. pipe() system call NAME pipe - create pipe SYNOPSIS
#include <unistd.h>
int pipe(int pipefd[2]);
DESCRIPTION
pipefd[0] refers to the read end of the pipe and
pipefd[1] refers to the write end of the pipe.
RETURN VALUE
On success, zero is returned. On error, -1 is
returned, and errno is set appropriately.
Example: pipe.c

5. Named pipe (FIFO) When not father-child related
Accessed using the filesystem
i.e. a special file
Creation:
mkfifo <fifoname>
In C use
mkfifo() - C-Library function
mknod() system call.