34.1. Overview

A process group is a set of one or more processes sharing the same process group identifier (PGID). A process group ID is a number of the same type (pid_t) as a process ID. A process group has a process group leader, which is the process that creates the group and whose process ID becomes the process group ID of the group. A new process inherits its parent’s process group ID.

A process group has a lifetime, which is the period of time beginning when the leader creates the group and ending when the last member process leaves the group. A process may leave a process group either by terminating or by joining another process group. The process group leader need not be the last member of a process group.