HP OpenVMS Systems Documentation

If you use two or more contradictory qualifiers on a command line, the right-most qualifier overrides the others.

Some commands contain conflicting qualifiers that cannot be specified in the same command line. If you use incompatible qualifiers, the command interpreter displays an error message.

Following is an example of conflicting qualifiers. Note that the PRINT command accepts only the /COPIES=2 and the /NOBURST qualifiers because they are the right-most qualifiers in the command line:

$ PRINT MYFILE/COPIES=3/BURST/COPIES=2/NOBURST EARTH.TXT

Qualifiers can accept keywords, file specifications, character strings, and numeric values. When you enter a value for a qualifier, separate the qualifier and the value with either an equal sign (=) or a colon (:).

Some qualifier keywords require additional information. In these cases, separate the keyword from its value with a colon or an equal sign.

To specify multiple keywords that require values, enclose the list in parentheses and separate the keyword and value with either an equal sign (=) or a colon (:).

Examples

• Either command in this example is valid:

  $ PRINT/COPIES=3 MYFILE.DAT

  $ PRINT/COPIES:3 MYFILE.DAT

• This is an example of a qualifier that requires additional information; the keyword "PROTECTION" is separated from its value by a colon or an equal sign (=):

  $ SET SECURITY/PROTECTION:GROUP:RW MYFILE.DAT

  $ SET SECURITY/PROTECTION=GROUP=RW MYFILE.DAT

• This is an example of a qualifier that requires multiple keywords, each of which require multiple values:

  $ SET SECURITY/PROTECTION=(OWNER=RWD,GROUP=RW) myfile.dat

  $ SET SECURITY/PROTECTION=(OWNER:RWD,GROUP:RW) myfile.dat

Certain commands and qualifiers (such as the PRINT/AFTER command) accept date and time values. You can specify these values in one of the following formats:

• Absolute time
• Delta time
• Combination time (combines absolute and delta time formats)

Absolute time is a specific date or time of day. The format for absolute time is as follows:

The fields are as follows:

The following rules apply when specifying absolute time:

• You can truncate the date or the time on the right.
• If you specify both a date and a time, include a colon between them.
• The date must contain at least one hyphen.
• You can omit any of the fields within the date and time as long as you include the punctuation marks that separate the fields.
• A truncated or omitted date field defaults to the corresponding fields for the current date.
• A truncated or omitted time field defaults to zero.
• If you specify a past time in a command that expects the current or a future time, the current time is used.

You can also specify an absolute time as one of the following keywords:

The following table shows examples of absolute time specifications:

Delta time is an offset (a time interval) from the current date and time to a time in the future. The general format of a delta time is as follows:

The fields are as follows:

If a qualifier is described as a value that can be expressed as an absolute time, a delta time, or a combination of the two, you must specify a delta time as if it were part of a combination time. For example, to specify a delta time value of five minutes from the current time, use "+:5" (not "0-0:5").

The following rules apply when specifying delta time:

• You can truncate a delta time on the right.
• If you specify the number of days, include a hyphen.
• You can omit fields within the time as long as you include the punctuation that separates the fields.
• If you omit the time field, the default is zero.

The following table shows some examples of delta time specifications:

To combine absolute and delta times, specify an absolute time plus or minus a delta time. Use one of the following formats:

    "[absolute time][+delta time]"

     [absolute time][-delta time]

The variable fields and default fields for absolute and delta time values are the same as those described in the preceding sections.

The following rules apply when specifying combination time:

• Precede the delta time value by a plus or minus sign. (Note that the minus sign is the same keyboard key as the hyphen.)
• Enclose the entire time specification in quotation marks if a plus or minus sign precedes the delta time value.
• Omit the absolute time value if you want to offset the delta time from the current date and time.
• Specify date and time information as completely as possible.

The following table shows some examples of combination time specifications:

At the DCL prompt, you can recall previously typed command lines to avoid retyping long command lines. Once a command is displayed, you can reexecute or edit it.

On OpenVMS VAX systems, the recall buffer holds up to 20 previously entered commands.

On OpenVMS Alpha systems, the recall buffer holds up to 254 previously entered commands.

You can display your previously entered commands by using one of the following methods:

• Pressing Ctrl/B
• Using up arrow and down arrow keys
• Using the RECALL command

Pressing Ctrl/B once recalls the previous command line. Pressing Ctrl/B again recalls the line before the previous line and so on to the last saved command line.

3.8.2 Using Arrow Keys

Using the up arrow and down arrow keys recalls the previous and successive command, respectively. Press the arrow keys repeatedly to move through the commands.

3.8.3 Using the RECALL Command

To examine previously typed command lines, type RECALL/ALL. After reviewing the available commands, you can recall a particular command line by typing RECALL and the number of the desired command.

You can also follow RECALL with the first characters of the command line you want to display. RECALL scans the previous command lines (beginning with the most recent one) and returns the first command line that begins with the characters you typed.

Examples

1. This is a sample display generated by typing RECALL/ALL:

   $ RECALL/ALL

   1 SET DEFAULT DISK2:[MARSHALL] 2 EDIT ACCOUNTS.COM 3 PURGE ACCOUNTS.COM 4 DIRECTORY/FULL ACCOUNTS.COM 5 COPY ACCOUNTS.COM [.ACCOUNTS]* 6 SET DEFAULT [.ACCOUNTS]

2. The following example shows how to recall the fourth command line:

   $ RECALL 4

   
   After you press Return, the system displays the fourth command in the list at the DCL prompt. (The RECALL command itself is not placed in the buffer.)
3. The following example shows how to recall a previously entered command, EDIT ACCOUNTS.COM:

   $ RECALL E

   
   After you press Return, the system displays the following command line:

   $ EDIT ACCOUNTS.COM

To erase the contents of the recall buffer, enter the RECALL command with the ERASE qualifier. For example:

$ RECALL/ERASE

For security reasons, it is good practice to erase the contents of the recall buffer after you have entered commands that include passwords.

3.9 Editing the DCL Command Line

At the DCL command level, you can use many individual keys and key sequences to change what you type. Although different types of terminals have different operating characteristics, most have standard function keys and keys that can be used with line editors.

3.9.1 SHOW TERMINAL Command

To see whether line editing is enabled on your terminal, enter the SHOW TERMINAL command. The current status of line editing is displayed in the first column under Terminal Characteristics.

In the following example, line editing is not enabled:

$ SHOW TERMINAL

Terminal: _VTA130:    Device_Type: VT200_Series  Owner: ROHBA
LAT Server/Port: L121/Port_3
Physical terminal: _LTA130:
   Input:   9600      LFfill:  0      Width:  80      Parity: None
   Output:  9600      CRfill:         Page:   24
Terminal Characteristics:
 Interactive        Echo               Type_ahead       No Escape
 No Hostsync        TTsync             Lowercase        Tab
 Wrap               Scope              No Remote        No Eightbit
 Broadcast          No Readsync        No Form          Fulldup
 No Modem           No Local_echo      No Autobaud      Hangup
 No Brdcstmbx       No DMA             No Altypeahd     Set_speed
 No Line Editing    Insert editing     No Fallback      No Dialup
 No Secure server   Disconnect         No Pasthru       No Syspassword
 No SIXEL Graphics  No Soft Characters No Printer Port  Numeric Keypad
 ANSI_CRT           No Regis           No Block_mode    Advanced_video
 No Edit_mode       DEC_CRT            No DEC_CRT2

You can use the SET TERMINAL command to alter the way in which your terminal edits a DCL command line. By default, changes made with the SET TERMINAL command apply only to the current session. To set the terminal each time you log in, you can include SET TERMINAL commands in your LOGIN.COM file.

SET TERMINAL/LINE_EDIT

To enable line editing, enter the SET TERMINAL/LINE_EDIT command:

$  SET TERMINAL/LINE_EDIT

SET TERMINAL/INSERT and SET TERMINAL/OVERSTRIKE

You can edit a command line in either insert or overstrike mode. In insert mode, the character you type is inserted to the left of the cursor. In overstrike mode, the character you type overwrites the character indicated by the cursor.

To change editing modes for a single command line, press Ctrl/A (Ctrl/A acts as a toggle). To change edit modes for your session, enter either the SET TERMINAL/INSERT or SET TERMINAL/OVERSTRIKE command.

SET TERMINAL/WRAP

If you use the SET TERMINAL/WRAP command, when you enter more characters than will fit on one line of the terminal screen, the text wraps to the next line. If you use the SET TERMINAL/NOWRAP command, when you enter more characters than will fit on one line of the terminal screen, the terminal types over the last character on the line.

You can edit only the line where your cursor appears. When text wraps, you cannot use the up arrow key to move the cursor up to edit the previous line. To move the cursor up to the previous line, use the Delete key and delete all the characters in the current line.

3.9.3 Deleting Portions of the Command Line

The Delete key on your keyboard is marked with either the word Rubout, the word Delete, or an X in a left-pointing arrow, depending on the type of terminal you are using. The Delete key back spaces over the most recently entered character and deletes it. On a hardcopy terminal, the deleted letters are displayed between backslash characters so you can see what is being deleted. On a video display terminal, pressing the Delete key erases the character from the screen and moves the cursor backwards.

In contrast, the Backspace key (or the left arrow key) back spaces over characters but does not delete them.

If line editing is enabled, you can use Ctrl/U to delete characters from the beginning of the line to the current cursor position. If line editing is not enabled, you can use Ctrl/U to cancel an entire line. The system ignores the line and redisplays the DCL prompt.

3.10 Defining Terminal Keys

A key definition is a string of characters that you assign to a particular terminal key. When a key is defined, you can press it instead of typing the string of characters. A key definition usually contains all or part of a command line. Using key definitions, you can customize your keyboard so that you can enter DCL commands with fewer keystrokes. When you press a defined key, the system either displays the command on your terminal or executes the command, depending on whether the command was defined using the /TERMINATE qualifier.

Some definable keys are automatically enabled for definition (for example, keys PF1 to PF4 and keys F17 to F20 on LK201 keyboards). However, before you can define other keys, including KP0 (keypad 0) to KP9 and the keypad keys period, comma, minus, and Enter, you must enable them for definition by entering either the SET TERMINAL/APPLICATION_KEYPAD or the SET TERMINAL/NONUMERIC command.

3.11 Summary of Key Sequences

The following sections describe keys and key sequences that you can use to perform specific operations.

3.11.1 Keys That Enter DCL Commands

The following keys enter DCL commands:

• Ctrl/Z and F10
  Signals the end of the file for data entered from the terminal. Ctrl/Z displays as Exit. This key is available only on an LK201 keyboard.
• Return
  Sends the current line to the system for processing. On some terminals, the Return key is labeled CR. If you are not already logged in, Return initiates a login sequence.

The following keys interrupt DCL commands:

• Ctrl/C and F6
  During command entry, cancels command processing. Ctrl/C displays as Cancel. This key is available only on an LK201 keyboard.
• Ctrl/T
  Momentarily interrupts terminal output to display a line of statistical information about the current process. This display includes your node and user name, the time, the name of the image you are running, and information about system resources used during your current terminal session.
  You can also use Ctrl/T to determine whether the system is operating. Ctrl/T does not return information if the system is temporarily unresponsive or if your terminal is set to NOBROADCAST. To use Ctrl/T, you must first enter the SET CONTROL=T command (in the system login command procedure, in your personal login command procedure, or interactively).
• Ctrl/Y
  Interrupts command processing. Ctrl/Y displays as Interrupt. You can disable Ctrl/Y with the command SET NOCONTROL=Y.
  Under most conditions, Ctrl/Y returns you to the DCL prompt. The program running is still active. You can enter any built-in command then continue the program with the CONTINUE command. (Press Ctrl/W to refresh the screen after you enter the CONTINUE command.)