Open System Services Porting Guide (G06.29+, H06.06+, J06.03+)

root fileset The fileset with the device number of 0, normally containing the root directory for the OSS file
system in an HP NonStop system. HP recommends that this fileset be named “root”.
save file A file created by the Inspect subsystem in response to a command from a debugger. A save file
contains enough information about a running process at a given time to restart the process at the
same point in its execution. A save file contains an image of the process, data for the process,
and the status of the process at the time the save file was created.
A save file can be created through an Inspect SAVE command at any time. A save file called a
saveabend file can be created when a process’s SAVEABEND attribute is set and the process
terminates abnormally. Other debuggers can create a save file but refer to the result as a process
snapshot file.
See also process snapshot file. .
saveabend file A file containing dump information needed by the system debugging tool. In UNIX systems, such
files are usually called core files or core dump files. A saveabend file is a special case of a save
file. See also save file and process snapshot file.
segment An aggregate of consecutive virtual addresses that are identified and managed as an entity, with
consistent access and other properties. A data segment contains data, as opposed to instructions.
A code segment contains instructions and some constant data.
See also selectable segment, flat segment, unitary segment (unitSeg).
selectable segment A data segment that starts at address 0x80000 and can be up to 127.5 MB in size; thus all
selectable segments occupy the same portion of 32-bit address space. A process can have an
arbitrary number of selectable segments, but select at most one at a time to be visible in that
reserved address range. Selectable segments are a legacy TNS mechanism, still supported on
NonStop systems. SEGMENT_ALLOCATE_ creates selectable segments by default;
SEGMENT_ALLOCATE64_ does so optionally. The selected segment can be dynamically switched
by calls to the SEGMENT_USE_ procedure. The effect is similar to a rapid overlaying of one large
data area. Contrast with flat segment.
See also segment.
semaphore A mechanism used to serialize the operations of multiple processes or threads. For example, a
semaphore can coordinate access to a shared data object.
server application An application that provides a service to a client application. Execution of remote procedure
calls is an example of such a service.
session A set of process groups associated for job control purposes. A session can have a controlling
terminal.
session leader The process that created a session.
session lifetime The period that begins when a session is created and ends when the lifetime of the last remaining
process group of the session ends.
shared memory An interprocess communication mechanism that allows two or more processes to share a given
segment or other region of memory. Selectable segments cannot be shared with flat segments,
or vice versa. Segments created with SEGMENT_ALLOCATE_ or SEGMENT_ALLOCATE64_
cannot be shared with segments created by shmget(), or vice versa.
shared run-time
library (SRL)
A collection of procedures whose code and data can be loaded and executed only at a specific
assigned virtual memory address (the same address in all processes). SRLs use direct addressing
and do not have run-time resolution of links to and from the main program and other independent
libraries. Contrast with dynamic-link library (DLL).
shell A program that interprets sequences of text input as commands. A shell can operate on an
input stream or it can interactively prompt and read commands from a terminal.
1.
2. An envelope of code that provides a convenient way to call a procedure in another execution
environment.
signal The method by which an environment notifies a process of an event. Signals are used to notify
a process when an error or some other occurrence of interest has occurred. On NonStop systems,
signals are characterized as deferrable or nondeferrable. Nondeferrable signals are those
generated by the system when a process performs some action that prevents continued execution
of the current instruction stream, such an attempt to access an unusable address. OSS processes
can send deferrable signals to other OSS processes; guardian processes cannot send signals to
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