System V IPC vs POSIX IPC

Question

1. What are the differences between System V IPC and POSIX IPC ?
2. Why do we have two standards ?
3. How to decide which IPC functi

Answer 1

• Systen V and POSIX IPC are two different, but related implementations of the same thing.

"Unix System V, commonly abbreviated SysV (and usually pronounced—though rarely written—as "System Five"), is one of the first commercial versions of the Unix operating system. It was originally developed by American Telephone & Telegraph (AT&T) and first released in 1983."

-Wikipedia

"POSIX or "Portable Operating System Interface [for Unix]" is the name of a family of related standards specified by the IEEE to define the application programming interface (API)"

-Wikipedia

• Systm V was there earlier. POSIX evolved out of the standardization initiative by IEEE.

• GNU/Linux is partially compliant with POSIX. Which one to use depends on which OS you are using this IPC. Most vendors are moving towards POSIX.

Unix Network Programming: Interprocess Communications v. 2 by Richard Stevens gives a good look into both of these.