Operating system services provide the core services needed
to operate and administer the application platform, and provide an interface
between application software and the platform. These services include the
following:
- Kernel operations provide low-level services necessary to create and
manage processes, execute programs, define and communicate signals, define
and process system clock operations, manage files and directories, and control
input-output processing to and from the external environment.
- Commands and utilities include mechanisms for operations at the operator
level, such as comparing, printing, and displaying file contents; editing
files; pattern searching; evaluating expressions; logging messages; moving
files between directories; sorting data; executing command scripts; and
accessing environment information.
- Real-time extension includes the application and operating system interfaces
needed to support those application domains requiring deterministic execution,
processing, and responsiveness. The extension defines the applications interface
to basic system services for input/output, file system access, and process
management.
- System management includes capabilities to define and manage user resource
allocation and access (i.e., what resources are managed and the classes
of access defined), configuration and performance management of devices,
file systems, administrative processes (job accounting), queues, machine/platform
profiles, authorization of resource usage, and system backup.
- Operating system security services specify the control of access to system
data, functions, hardware, and software resources by users and user processes.