Overview of Processes

A process can access most of its own attributes, but can access only a small subset of other processes' attributes. Therefore, process objects are modeled using two classes: os_this_process , which represents the current process, and os_process , which represents other processes. Other process-related information in this chapter covers the use of both process_status and process_group to manipulate one or more processes.

Many of the available process attributes are listed below.

Unique process ID (PID)

Set of zero or more child processes

Environment

Process group

Session ID

Set of blocked signals

Set of signals that are being ignored

Set of pending signals

Set of signal handlers

Set of resources

Current working directory

Root directory

umask

Real and effective user

Real and effective group

Set of supplementary groups

Priority

Set of three interval timers

Parent process (zombies are adopted by the init process)

State (running/runnable/sleeping/
suspended/idle/zombified)

Set of functions to call upon exit

Status (sleep/resume/suspend/terminate/ yield/priority/wait)

Unique process ID (PID)	Set of zero or more child processes
Environment	Process group
Session ID	Set of blocked signals
Set of signals that are being ignored	Set of pending signals
Set of signal handlers	Set of resources
Current working directory	Root directory
`umask`	Real and effective user
Real and effective group	Set of supplementary groups
Priority	Set of three interval timers
Parent process (zombies are adopted by the `init` process)	State (running/runnable/sleeping/ suspended/idle/zombified)
Set of functions to call upon exit	Status (sleep/resume/suspend/terminate/ yield/priority/wait)

The following classes are covered in the next four sections of this chapter.

os_this_process
os_process
os_process_status
os_process_group