Inter-Process Communication (IPC) is a set of techniques for the exchange of data among multiple threads in one or more processes.

1. Inter Process Communication - IPC
Inter-Process Communication (IPC) is a set of techniques for the exchange of data among
multiple threads in one or more processes. IPC is part of Linux System Programming. In
inter-process communication processes may be running on one or more computers
connected by a network. IPC is used to communicate one process to another process with in
the system or network. IPC techniques helps us to understand how data is transfer with in
system from on drive to another drive, from flash-drive to drive. IPC include many
techniques to understand flow of data with in the system. It include many techniques like
PIPES, FIFO (named pipes), Message Queues, Shared memory and Threads to communicate
between process. Process duplication and Process Replacement is also a part of IPC
techniques. To synchronize multiple processes which communicate in between techniques
used is semaphores, signal.
Types of Inter-Process communication:-
• Signals - Sent by other processes or the kernel to a specific process to indicate
various conditions.
• Pipes - Unnamed pipes set up by the shell normally with the character to route output
from one program to the input of another.
• FIFOS - Named pipes operating on the basis of first data in, first data out.
• Message queues - Message queues are a mechanism set up to allow one or more
processes to write messages that can be read by one or more other processes.
• Semaphores - Counters that are used to control access to shared resources. These
counters are used as a locking mechanism to prevent more than one process from
using the resource at a time.
• Shared memory - The mapping of a memory area to be shared by multiple processes.
• Message queues, semaphores, and shared memory can be accessed by the processes
if they have access permission to the resource as set up by the object's creator. The
process must pass an identifier to the kernel to be able to get the access.
Rules of IPC:-
• Safety/mutual exclusion: No two processes may be simultaneously inside their critical
regions.
• Liveliness/progress: No process running outside its critical region may block other
processes.
• Contention: If two processes enter a critical region, the conflict should be resolved in
favor of one.
• Fairness/deadlock: No process should have to wait for an unfair amount of time or
forever to enter its critical region.
Conclusion:-
If these techniques were not developed processes would not have been able to communicate
with another processes also sharing of information could not take place.
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