PGID

See process group ID.

PID

See process ID.

pid_t

Is the C-language programmatic data type used for declaring variables which hold PID values. It has always been and will continue to be a 32-bit integer. Its definition was introduced in HP-UX release 8.0.

process group ID

This is an integer value which is used as the handle or identifier for a process group. Its value is usually the same as the PID of the group leader process. Also known as PGID. See setpgrp(2).

process ID

An integer value which is used as the handle or identifier for an active process. Values are reused as processes are destroyed and new processes created (and assigned an ID previously used by some other process). Also known as PID. Note that PIDs are also used as process group IDs (PGIDs) and session IDs (SIDs).

process_id_min, process_id_max

Kernel tunable parameters introduced in HP-UX 11i v3. They specify the lowest and highest values to use for process IDs when creating new processes. Their default values are 0 and 30,000, respectively, to provide an environment compatible with that of prior versions of HP-UX.

session ID

An integer value that is used as the handle or identifier for a session. Its value is usually the same as the process ID of the session leader process. See setsid(2).

SID

See session ID

Administrator Notes

This section covers information for the system administrator.

Kernel Tunable Parameters

Several kernel tunable parameters control the number of active processes and the values used for PIDs:

∙nproc – Specifies a limit on the total number of active processes in the system. The maximum value for this parameter on prior HP-UX versions was 30,000. For 11i v3, it is 60,000.2 Setting values higher than 30,000 can cause some applications to fail.

2The software might allow the nproc value to exceed 60,000. However, larger values have not been tested by HP and are not supported.

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