A simple daemonless system for broadcasting messages locally.
bus is a light-weight alternative to a two-phase flexible barrier.

bus uses a System V semaphore array and System V shared memory.
Buses are named; the key of the semaphore array and the
shared memory is stored in a regular file.

The shared memory used by bus is always 2048 bytes. Additionally
all messages should be encoded in UTF-8 and not contain any NULL
characters, except they MUST always end with a zero byte.
Furthermore messages should be prefixed with the process
identifer of the process whence the message originated, followed
by a space. If the process is ephemeral, 0 should be used instead
of the process identifier.

Communication over bus is synchronous. The broadcast call does
not return until all listeners have received (and copyied)
the message.

The software package contains a C library and a command line
utility. The package python-bus provides a Python 3 module.