TCL overview

Terminal Control Language (TCL) is the gateway to all D3 functionality. TCL is a system-level command language with system-defined or user-defined statements that can be executed individually or sequentially. System-defined statements are called TCL commands. User-defined statements are: macros, menus, and cataloged FlashBASIC programs.

The first word of a TCL statement must be either a system command, macro, menu, or cataloged BASIC program.

The : is the TCL prompt. TCL commands can be typed when the TCL prompt displays. The completed command is entered for processing by pressing CTRL+M or Enter. Because mistakes do occur, TCL editor and TCL stack facilities are provided.

The TCL editor allows corrections to commands after they are entered, but before they are executed. The TCL stack editor stacks each command entered at the TCL prompt and allows you to recall commands for correction and/or execution.

TCL commands include the Access Query Language (AQL) and spooler commands. AQL is a system-level information retrieval language that allows you to query your database without writing complex programs. The spooler commands allow you to control how information is output to the printer.

Example(s)

who
create-file test.file 3 7
copy md * (t
compile bp *
sort entity by name name

Dot stack
The dot stack displays the entries entered at TCL. Every unique command that is typed at the TCL prompt is saved in a file on the dm account called tcl-stack.
Dummy restore
The dummy restore is a method of validating that the save-type (account-save, file-save, and so on) backup are restored.
Dummy save
The dummy save performs the save command without actually writing to magnetic media.
Editing TCL commands
The TCL editor uses the Update processor to enter commands, so the TCL editor commands are similar to the Update processor commands. A TCL command may be created and edited as if it were a paragraph. Pressing CTRL+M or Enter within the TCL command processes the entry.
BREAK key
While a system process is running, it remains in control of your terminal. Typically, you want the system process to complete its work and return control to the TCL level. If you press BREAK while a process is running, you will suspend the process and drop into a debugger.
Level pushing
Level pushing is a term used to describe the ability to interrupt a process, invoke a new TCL prompt, and execute any valid TCL command.
Macros
A macro is a process that executes one or more TCL commands. Macros are stored in the master dictionary with the name of the macro as the item-ID. The macro processor is provided for simple TCL procedures. In general, complex procedures should be written as BASIC programs.
Macro statements
The following macro statements are supported:
Menus
A menu provides a selection of processing choices. Menus are items in the master dictionary. The menu processor (me in attribute 1 of item) automatically formats the menu on the screen. You can then select one of the menu options for processing by entering the option number. The format of the menu item in the master dictionary is:
Options (TCL)
The print (p and no pause (n options are the only standard options available to every TCL command.
Paragraph
The paragraph is a macro language allowing execution of TCL statements, looping structures, data stacking, screen input and output, and branching.
@ shell variable
The @ character indicates a D3 shell variable.
Spooler overview
The spooler controls all output that is sent to a printer. Spooler is an acronym derived from simultaneous peripheral output online.
Tape devices overview
Tape devices are storage medium for reading and writing tapes.
TCL stack
When a command is entered at the TCL prompt, the system saves the command in the TCL stack file of the dm account. Your stack is not terminal dependent. If you leave a terminal without logging off, another user can use the terminal under your user-ID. This causes the new user to step-on the stack.

Parent topic: Terminal control language