Document revision date: 19 July 1999

A default is the value supplied by the operating system when you do not specify one yourself. For example, if you do not specify the number of copies as a qualifier for the PRINT command, the system uses the default value 1. The operating system supplies default values in several areas, including command qualifiers and parameters. The defaults that the operating system uses with specific commands are described in each command's entry in the OpenVMS DCL Dictionary.

2.9.2 Informational System Messages

The system responds to some commands by displaying information in a system message about what it has done. For example, when you use the PRINT command, the system displays the job identification number it assigned to the print job and shows the name of the print queue the job has entered.

$ PRINT MYFILE.LIS [Return] Job MYFILE (queue SCALE_PRINT, entry 210) started on SYS$PRINT

Not all commands display informational messages. Successful completion of a command is usually indicated when the DCL prompt returns. Unsuccessful completion is always indicated by one or more error messages.

2.9.3 System Error Messages

If you enter a command incorrectly, the system displays a system message and prompts you for the correct command string, as the following example shows:

$ CAPY [Return] %DCL-W-IVVERB, unrecognized command verb - check validity and spelling \CAPY\ $

The format for the 3-part code is:

DCL-W-IVVERB

where:

DCL	The OpenVMS facility or component name that returned the error. In this example, the message is from DCL, the default command interpreter.
W	A severity level that indicates a warning. Other severity levels include S (success), I (information), E (error), and F (fatal or severe error).
IVVERB	The type of message. The message can be identified by the mnemonic IVVERB in the OpenVMS system messages documentation or by using the Help Message utility (MSGHLP) described in Section 2.10.3.

You can also receive system error messages during command execution if the system cannot perform the function you have requested. For example, if you type a PRINT command correctly but the file you specify does not exist, the PRINT command informs you of the error with a message like the following:

$ PRINT NOFILE.DAT [Return] %PRINT-E-OPENIN, error opening CLASS1:[MAYMON]NOFILE.DAT; as input -RMS-E-FNF, file not found $

The first message is from the PRINT command. It tells you it cannot open the specified file. The second message indicates the reason for the first; that is, the file cannot be found. RMS refers to the OpenVMS file-handling software, Record Management Services; error messages related to filehandling are generally OpenVMS RMS messages.

2.9.4 Checking Your Current Process

If you suspect that your process is not doing what you think it should be doing, press Ctrl/T. Ctrl/T displays a single line of statistical information about the current process. The statistical information includes node and user name, current time, current process, central processing unit (CPU) usage, number of page faults, level of I/O activity, and memory usage, which is listed in number of CPU-specific pages.

When you press Ctrl/T during an interactive terminal session, it momentarily interrupts the current command, command procedure, or image to display statistics. Although Ctrl/T disrupts the characters on the screen, it does not affect any procedure or editing session. For example, if a user named MCCARTHY on node GREEN presses Ctrl/T while using the EVE editor, the following line is displayed in the EVE message window:

GREEN::MCCARTHY 13:45:02 EVE CPU=00:00:03.33 PF=778 IO=295 MEM=315

To refresh the screen, press Ctrl/W.

Ctrl/T is disabled by default. If you know your system is running and Ctrl/T does not display statistical information, you can enable Ctrl/T with the DCL command SET CONTROL=T. Enter the command at DCL level (at the dollar sign ($) prompt), then press Ctrl/T again. Ctrl/T will remain in effect for the duration of your process, unless it is disabled from a program or command such as SET NOCONTROL=T. Note that your terminal must be set to BROADCAST mode for Ctrl/T to display on your screen. To set your terminal to BROADCAST mode, enter the DCL command SET TERMINAL/BROADCAST at the DCL prompt.

2.10 Getting Help About the System

When you are logged in to the operating system, you can obtain information about using the system and available commands by using the HELP command. You can also get help on system messages by entering the HELP/MESSAGE command as shown in Section 2.10.3.

2.10.1 Using Online Help

Use the following procedure to get help on OpenVMS commands and utilities:

Step	Task
1	Enter HELP at the DCL prompt and press Return. HELP displays a list of topics and the Topic? prompt.
2	To see information about one of the topics, type the topic name after the prompt and press Return.
3	If you want information on one of the subtopics, type the name after the prompt and press Return. HELP displays information about that subtopic.
4	To redisplay the SHOW USERS topic and the list of subtopics, enter a question mark (?) at the Subtopic? prompt. If you want to read all of the listed subtopics, enter an asterisk (*).
5	If you want information on another topic, press Return. Help displays the Topic? prompt.
6	To exit Help, press Return until you return to the DCL prompt.

The following example shows the commands that you would enter to look for help about the SHOW USERS command:

$ HELP HELP . . (HELP message text and subtopics) . Topic? SHOW USERS [Return] SHOW USERS Displays the user name and node name (in a VAXcluster environment) of interactive, subprocess, and batch users on the system. Format SHOW USERS [username] Additional information available: PARAMETER QUALIFIER /BATCH /CLUSTER /FULL /INTERACTIVE /NETWORK /NODE /OUTPUT /SUBPROCESS Examples SHOW USERS Subtopic? EXAMPLES SHOW USERS Examples . . (SHOW USERS Examples message text and subtopics, if any) . SHOW USERS Subtopic? [Return] SHOW Subtopic? [Return] Topic? [Return] $

2.10.2 Getting Help on Specific Commands

If you know the command you need information about, enter HELP and the command name. For example, to get help about the SHOW USERS command enter the following command:

$ HELP SHOW USERS [Return]

If you need help but do not know what command or system topic to specify, enter the command HELP with the word HINTS as a parameter. Each task name listed in the HINTS text is associated with a list of related command names and system information topics.

The OpenVMS DCL Dictionary contains more information about the HELP command.

2.10.3 Getting Help on System Messages

Use the Help Message utility (MSGHLP) to get online help for system messages. To display information on how the last command completed, type:

$ HELP/MESSAGE

You can also display information about a specific message by including the message identifier or words from the message text. For example:

$ HELP/MESSAGE BADACP

A message and its description can also be accessed by entering the message status code. For example:

$ HELP/MESSAGE/STATUS=%X00038090 [Return]

If you do not know the message status code, you can view it by entering the command SHOW SYMBOL followed by the $STATUS global symbol. For example:

$ SHOW SYMBOL $STATUS $STATUS == "%X00038090"

The Help Message utility allows you to update the messages database with your own messages or to add comments to existing message descriptions. You can also extract a subset of messages from the messages database to create and print your own customized messages documentation. For details on how to use the Help Message utility, see OpenVMS System Messages: Companion Guide for Help Message Users.

2.11 Logging Out of the System

When you finish using the system, always log out. This prevents unauthorized users from accessing your account and the system. It is also a wise use of system resources; the resources you no longer need are available for other users.

To log out, enter LOGOUT at the DCL prompt. For example:

$ LOGOUT [Return]

The system displays a message, similar to the following message, confirming that you are logged out of the system:

$ LOGOUT [Return] HARRIS logged out at 11-DEC-1996 12:42:48.12

You can log out of the system only when you are at the DCL prompt ($). You cannot enter the LOGOUT command while you are compiling or executing a program, using a text editor (such as EDT or EVE), or running a utility (such as Mail). First you must exit the program, editor, or utility. When the system displays the DCL prompt, you can log out.

2.11.1 Obtaining Accounting Information

To find out how much time you spent at the terminal (elapsed time), how much computer time you used (charged CPU time), and other accounting information, enter LOGOUT/FULL at the DCL prompt. For example:

$ LOGOUT/FULL [Return]

The system displays information similar to the following:

SIMPSON logged out at 11-DEC-1996 12:42:48.12 Accounting information: Buffered I/O count: 8005 Peak working set size: 212 Direct I/O count: 504 Peak virtual size: 770 Page faults: 1476 Mounted volumes: 0 Charged CPU time:0 00:00:50.01 Elapsed time:0 02:27:43.06

2.11.2 Ending a Remote Session

You can end a remote session in two ways:

• Use the remote system's logout procedure (for example, on an OpenVMS system, use the LOGOUT command).
• Press Ctrl/Y twice to obtain the host system's prompt, which asks whether you want to abort the remote session. Answer YES (Y) if you want to abort the remote session. This method works regardless of the type of system running on the remote node.

When you end a remote session, the system displays the message "%REM-S-END, control returned to node NODENAME::" and returns you to the process on the system from which you made the remote node connection.

2.11.3 Lost Network Connections

If the network connection to a remote system is lost, DECnet will retransmit your data in an attempt to reestablish communications. If DECnet is unable to reestablish communications within a predetermined timeout period, your connection to the remote system is terminated and the system displays the message "Path lost to partner."

2.12 Logging Out Without Compromising System Security

Logging out of a session conserves system resources and protects your files. Leaving a terminal on line represents one of the greatest sources of inside break-ins. When you leave your terminal on line and your office open, you have effectively given away your password and your privileges and have left your files and those of the other members of your group unprotected. Any user can easily and quickly transfer all files accessible through your account. A malicious insider could rename and delete your files and any other files to which you have write access. If you have special privileges, especially privileges in the Files or All category, a malicious user can do major damage.

Log out when you leave your office even for a brief period of time. If you have performed remote logins, you must log out of each node.

2.12.1 Reasons to Clear Your Terminal Screen

Clear your screen each time you log out of a terminal to ensure that your user name, node name, and operating system are not revealed to anyone else. If you are logging out after a remote login, the name of the node to which you return (the local node) is also revealed. If you access multiple accounts remotely over the network, the final sequence of logout commands reveals all the nodes and user names that are accessible to you on each node (excluding the name of the furthest node reached). To those who can recognize the operating system from the prompt or a logout message, these displays also reveal the operating system.

At some sites, it might be important to leave nothing but the logout message on your screen, as follows:

• If you are using a VT200 or later series terminal, you can clear the screen by pressing the Set-Up key and selecting the item from the resulting menu that corresponds to Clear Display.
• If you are using a VT100 series terminal, press the Set-Up key. Then press the key marked for reset (the 0 key) followed by the Return key.
  Alternatively, to preserve temporary parameters, press the Set-Up key and then press the key marked 80/132 columns (the 9 key) twice.

After the screen clears, the cursor is positioned at the top of the screen, next to the DCL prompt. Enter the DCL command LOGOUT at the prompt. The only information remaining after you log out is your logout command and the logout completion message. For example:

$ LOGOUT RDOGWOOD logged out at 11-DEC-1996 19:39:01.43

2.12.2 Disposing of Hardcopy Output

After you log out from a hardcopy terminal, remove, file, or dispose of all hardcopy output that might reveal sensitive information. Your security administrator should provide direction on preferred procedures. Many sites use paper shredders or locked receptacles for this purpose. Handle output that you plan to save just as carefully.

You should also dispose of hardcopy output if the system fails before you log out. In addition, if you will not be present when the system is initialized, turn your terminal off.

2.12.3 Breaking the Connection to a Dialup Line

Your security administrator might ask you to break the connection to a dialup line when you log out. If you anticipate no further immediate use of the line, use the LOGOUT command with the /HANGUP qualifier. The /HANGUP qualifier directs the system to automatically break the connection to the dialup line after you log out.

Breaking the connection to a dialup line:

• Prevents others from taking advantage of an open access line. To access the line, someone must know the access number and must personally redial.
• Is especially important if the dialup line you use is in a public area or where someone might use the terminal after you.
• Saves resources by reducing the required number of dialup lines.

This chapter describes how to use the DIGITAL Command Language. This chapter includes information about:

• Using DCL commands
• Constructing DCL commands
• Entering DCL commands
• Rules for entering DCL commands
• Entering parameters
• Entering qualifiers
• Entering dates and times as values
• Recalling commands
• Editing the DCL command line
• Defining terminal keys
• Summary of key sequences

For additional information, refer to:

• The OpenVMS DCL Dictionary and online help, for all the commands, qualifiers, and parameters discussed in this chapter
• The OpenVMS Guide to Extended File Specifications, for commands for use with Extended File Specifications

The DIGITAL Command Language (DCL) is a set of English-like instructions that tell the operating system to perform specific operations.

DCL commands let you do the following:

• Get information about the system
• Work with files
• Work with disks, magnetic tapes, and other devices
• Modify your work environment
• Develop and execute programs
• Provide security and ensure that resources are used efficiently

To enter a DCL command, type the command at the DCL prompt ($) and press Return. DCL is not case sensitive; you can enter commands in either uppercase or lowercase letters.

In the following example, the DCL command SHOW TIME is entered as follows:

$ SHOW TIME [Return]

The system responds by displaying the current date and time and returns the DCL prompt to indicate it is ready to accept another command:

11-DEC-1996 15:41:43 $

3.1.2 Commonly Used DCL Commands

The following table lists the DCL commands you use to perform a few common computing tasks:

Command	Task
COPY	Makes a copy of a specified file
CREATE	Creates files or directories
DELETE	Erases a specified file and removes it from a directory
DIRECTORY	Displays the contents of a directory (list of files)
EDIT	Views and changes the contents of a text file
LOGOUT	Ends your session
PRINT	Sends a specified file to a printer for printing
RENAME	Changes the name or the location of a specified file
SET	Controls how you see the system on the screen
SHOW	Displays the status of the system
TYPE	Displays the contents of a specified file on the screen

3.1.3 Key Sequences

In addition to these DCL commands, you can perform tasks by using specific key sequences. A key sequence is a shortcut or a way to get the system's attention while it is processing another command.

To enter a key sequence, hold down the Ctrl key while you press and release a second key.

The following table describes a few commonly used key sequences. (Additional key sequences are listed in Section 3.11.)

Key Sequence	Function
Ctrl/C	During command entry, cancels command processing. Ctrl/C displays on your screen as Cancel.
Ctrl/Y	Interrupts command processing. Ctrl/Y displays on your screen as Interrupt.
Ctrl/T	Displays information about the current process, unless the system is temporarily unresponsive or is set to NOBROADCAST. For more information on using Ctrl/T, see Section 2.9.

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