IBM i objects

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IBM i objects

An object is a named unit that exists (occupies space) in storage, and on which operations are performed by the operating system.

IBM i objects provide the means through which all data processing information is stored and processed by the IBM i operating system.

Objects are the basic units on which commands perform operations.

CL commands perform operations on the IBM i objects.

Several types of IBM i objects are created and used in the control language.

The system supports various unique types of objects. Some types identify objects common to many data processing systems, such as: 

  • Files
  • Programs
  • Commands
  • Libraries
  • Queues
  • Modules
  • Service programs

Different object types have different operational characteristics. These differences make each object type unique.

For example, because a file is an object that contains data, its operational characteristics differ from those of a program, which contains instructions.

Each object has a name. The object name and the object type are used to identify an object.

The object name is assigned by the user creating the object.

The object type is determined by the command used to create the object.

Library objects

A library is an object that is used to group related objects, and to find objects by name when they are used. Thus, a library is a directory to a group of objects. You can use libraries to group the objects into any meaningful collection.

Two objects with the same name and type can exist in different libraries.

Two different objects with the same name cannot exist in the same library unless their object types differ.

An object is identified within a library by the object name and type.

Objects that use the integrated file system are located in directories and can be found by using path names or object name patterns instead of searching libraries. You can also use these directories to locate objects.

Simple and qualified object names

The name of a specific object that is located in a library can be specified as a simple name or as a qualified name.

A simple object name is the name of the object only.

A qualified object name is the name of the library where the object is stored followed by the name of the object. In a qualified object name, the library name is connected to the object name by a slash (/).

Generic object names

Generic object names can be used when referring to multiple objects with similar names.

A generic name is identified by an asterisk (*) as the last character in the name.

For example, the generic name "ABC*" causes the system to search for all objects whose name begins with a quotation mark followed by the three letters ABC.

List of all objects with starting with TEST

 

Object naming rules

These rules are used to name all IBM i objects used in control language (CL) commands.

  • In the name of a single object, each part (the simple name and the library qualifier name) can have a maximum of 10 characters.
  • To distinguish a user-created object from an IBM-supplied object, you should not begin user-created object names with Q because the names of all IBM-supplied objects (except commands) begin with Q.
  • Duplicate names are not allowed for objects of the same type in the same library.

Default libraries

The library name is typically optional. Default will be either *CURLIB or *LIBL.

If the named object is being created, the current library is the default.

When the object is created, it is placed either in the current library or in the QGPL (the general purpose library ) if no current library is defined.

Database files and device files used by CL commands

Many of the IBM-supplied CL commands use database files and device files during processing.

All of the commands and files for all licensed programs that meet the criteria are included: 

The types of files included are:

– Database files: physical (PF) and logical (LF), including files with data and files used as model files (no data)

– Device files: tape (TAPF) and printer (PRTF)

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