Instance of a running program is a Process.

1. PYCH
PROCESS

2. DEFINITION
A running instance of a program is called
a process.
PYCH

3. THE FORK
fork() creates a new process by duplicating the
calling process. The new process, referred to as the
child, is an exact duplicate of the calling
process, referred to as the parent, except for the
following points . . .
PYCH

4. THE LIFE
fork()
TASK_RUNNING
(ready but not
running)
TASK_RUNNING
(running)
TASK_ZOMBIE
(running)
TASK_INTERRUPTIBLE
Or
TASK_UNINTERRUPTIBLE
(running)
Task forks
Dispatch
to run
Task
Preempted
Task Exits
Task Waits on
an Event
Event
Occurs
PYCH

5. THE PIECES
Memory
Signal Handlers
File Descriptor Table
Environment Variables
The program code, heap, stack, global variables.
Software interrupts, SIG*, signal handlers, SIGKILL, SIGSTOP.
stdin, stdout, stderr, open files
Getenv, setenv, parent environment
PYCH

6. THE RELATION
The init process
PYCH

7. THE DAEMON
Always runs in
the background
Always attached to the init process.
. yeah mostly!
The init process
PYCH

8. THE PYCH
To learn about the Python way
of Creating Processes,
Daemons, and Managing them.
PYCH