Job control terminology

The following defines terms associated with Job Control:

• Background Process-group -- a process-group that is a member of a session that established a connection with a controlling terminal and is not the foreground process-group.

• Controlling Process -- a session leader that established a connection to a controlling terminal.

• Controlling Terminal -- a terminal that is associated with a session. Each session may have at most one controlling terminal associated with it and a controlling terminal may be associated with at most one session. Certain input sequences from the controlling terminal cause signals to be sent to the process-groups in the session associated with the controlling terminal.

• Foreground Process Group -- each session that establishes a connection with a controlling terminal distinguishes one process-group of the session as a foreground process-group. The foreground process-group has certain privileges that are denied to background process-groups when accessing its controlling terminal.

• Orphaned Process Group -- a process-group in which the parent of every member in the group is either a member of the group, or is not a member of the process-group's session.

• Process Group -- each process in the system is a member of a process-group that is identified by a process-group ID. Any process that is not a process-group leader may create a new process-group and become its leader. Any process that is not a process-group leader may join an existing process-group that shares the same session as the process. A newly created process joins the process-group of its creator.

• Process Group Leader -- a process whose process ID is the same as its process group ID.

• Process Group Lifetime -- a time period that begins when a process-group is created by its process-group leader and ends when the last process that is a member in the group leaves the group.

• Process ID -- a positive integer that uniquely identifies each process in the system. A process ID may not be reused by the system until the process lifetime, process-group lifetime, and session lifetime ends for any process ID, process-group ID, and session ID sharing that value.

• Process Lifetime -- a time period that begins when the process is forked and ends after the process exits, when its termination has been acknowledged by its parent process.

• Session -- each process-group is a member of a session that is identified by a session ID.

• Session ID -- a positive integer that uniquely identifies each session in the system. It is the same as the process ID of its session leader.

• Session Leader -- a process whose session ID is the same as its process and process-group ID.

• Session Lifetime -- a time period that begins when the session is created by its session leader and ends when the lifetime of the last process-group that is a member of the session ends.