Getting Started with OpenVMS: A Guide for New Users (HP Technologies)

DCL defines several control characters to perform various functions. To use them, press the CTRL key, and then press the indicated key before releasing CTRL. Some are active at the DCL prompt but may be ignored by certain programs. Among them are the following:

Major functions:

• CTRL/A toggles the terminal between insert and overstrike modes (controls whether keyboard characters overwrite existing characters or are inserted between them).

• CTRL/B moves backward through the recall buffer (see "The Recall Buffer," above.) Equivalent to up-arrow.

• CTRL/C cancels the current operation (such as a search in an EDT text editor session) or DCL command. A given program or command may or may not treat CTRL/C and CTRL/Y as equivalent.

• CTRL/E moves the cursor to the end of the line.

• CTRL/H sounds the terminal bell or beep under some circumstances and may be used within the PHONE utility to sound the terminal bell of the other party.

• CTRL/J deletes the previous word under some circumstances.

• CTRL/L generates a formfeed character within some text editors.

• CTRL/M sometimes equivalent to ENTER or RETURN.

• CTRL/O toggles output to the terminal on or off. It is handy when a large amount of output is coming to the screen, which you do not need to see. When output is toggled off, the program or command continues to execute (and in fact, executes faster.) The program still generates the same output; it is simply not displayed on the screen. Broadcast messages automatically enable output when received, and so will not be missed.

• CTRL/P gains the attention of the hardware console subsystem when issued from the console terminal of certain hardware models, and only when specifically enabled. Many hardware models do not have a separate console processor, so this has the effect of halting the execution of OpenVMS. The general user never has occasion to use this; it is mentioned only as a caution to readers who may have their own OpenVMS computer hardware.

• CRTL/Q resumes output to the screen that has been frozen via CRTL/S or HOLD SCREEN (usually F1 on PC-style keyboards).

• CTRL/R refreshes the screen under some circumstances, such as within text editors and other full-screen programs. It is not used as widely as CTRL/W.

• CTRL/S freezes the screen. It is equivalent to HOLD SCREEN (usually F1 on PC-style keyboards). Use CTRL/Q or HOLD SCREEN to resume.

• CTRL/T displays a one-line status display containing your node, process name, system time, the name of your current program, accumulated CPU time, accumulated page faults, accumulated I/O operations, and current physical memory usage. After this status line, certain programs may display a one-line summary of their own progress.

• CTRL/U erases from the beginning of the line to the current cursor location. In older versions of OpenVMS, it discarded the entire line and performed a RETURN (ENTER.)

• CTRL/W refreshes the screen in most full-screen applications. It is sometimes equivalent to CTRL/R, but more widely used.

• CTRL/X causes any keystrokes in the type-ahead buffer to be discarded and otherwise functions like CTRL/U.

• CTRL/Y interrupts the current command procedure or program and displays the DCL prompt. You may exit the program by (1) issuing the EXIT command, allowing the program exit handlers to run, (2) issuing the QUIT command, preventing the exit handlers from running (not generally recommended), or (3) issuing another command which causes a program to run, thereby executing an implicit EXIT. If you do not wish to abort the program, use the CONTINUE command. You may sometimes continue a program even after issuing other commands, but only if the intervening commands are handled internally by DCL (such as SPAWN).

• CTRL/Z means end-of-file or end-of-input. It is used to signal many applications, such as text editors and the CREATE command, that you are finished entering information. It may sometimes be used to abort a DCL command that you are typing (if a valid verb and all required parameters are present when you press CTRL/Z, the command will be issued).

• Up-arrow moves backward (toward older commands) through the recall buffer.

• Down-Arrow moves forward (toward more recent commands) through the recall buffer.

• HOLD SCREEN is a toggle to freeze or resume output. It is identical to the combination of CTRL/S and CTRL/Q. PC keyboards usually use F1 for this function.

Minor or redundant functions:

• CTRL/D moves the cursor one position to the left under some circumstances. The left-arrow is usually preferred.

• CTRL/F moves the cursor one position to the right under some circumstances. The right-arrow is usually preferred.

• CTRL/I duplicates the function of the TAB key under some circumstances. TAB is usually preferred.

• CTRL/UP-ARROW causes a DECterm window to scroll backward, showing information that has scrolled off the top of the screen. It duplicates the function of the window scroll bar.

• CTRL/DOWN-ARROW causes a DECterm window to scroll forward, the opposite of CTRL/UP-ARROW