HP OpenVMS Systems Documentation

The following keys recall commands:

• Ctrl/B or up arrow
  Recalls up to 20 (VAX) or 254 (Alpha) previously entered commands.
• Down arrow
  Displays the next line in the recall buffer.

The following keys control cursor position:

• <X|, Delete
  Deletes the last character entered at the terminal. On some terminals, the Delete key is labeled RUBOUT. The Delete key also works when line editing is disabled.
• Ctrl/A and F14
  Switches between overstrike and insert mode. The default mode (as set with the SET TERMINAL/LINE_EDITING command) is reset at the beginning of each line. This key is available only on an LK201 keyboard.
• Ctrl/D and left arrow
  Moves the cursor one character to the left.
• Ctrl/E
  Moves the cursor to the end of the line.
• Ctrl/F and right arrow
  Moves the cursor one character to the right.
• Ctrl/H, Backspace, and F12
  Moves the cursor to the beginning of the line. This key is available only on an LK201 keyboard.
• Ctrl/I and Tab
  Moves the cursor to the next tab stop on the terminal. The system provides tab stops at every eighth character position on a line. Tab settings are hardware terminal characteristics that, in general, you can modify. The Tab key also works when line editing is disabled.
• Ctrl/J, Linefeed, and F13
  Deletes the word to the left of the cursor. This key is available only on an LK201 keyboard.
• Ctrl/K
  Advances the current line to the next vertical tab stop.
• Ctrl/L
  Causes the cursor to go to the beginning of the next page. This use of Ctrl/L is ignored when line editing is enabled.
• Ctrl/R
  Repeats the current command line and leaves the cursor positioned where it was when you pressed Ctrl/R.
• Ctrl/U
  Deletes all text in the current input line that is to the left of the cursor.
• Ctrl/V
  Turns off some of the line editing function keys. For example, if you press Ctrl/V followed by Ctrl/D, a Ctrl/D is generated instead of the cursor moving left one character. Ctrl/D is a line terminator at DCL level.
  When combined with Ctrl/V, characters that are not line terminators have no effect. Examples are Ctrl/H and Ctrl/J. However, certain control keys, such as Ctrl/U, retain their line editing functions.
• Ctrl/X
  Cancels the current line and deletes data in the type-ahead buffer.
• F7, F8, F9, F11
  Reserved by Compaq.

The following keys control screen display:

• Ctrl/O
  Alternately suspends and continues display of output to the terminal. Ctrl/O displays as Output off and Output on.
• Ctrl/S
  Suspends terminal output until Ctrl/Q is pressed.
• Ctrl/Q
  Resumes terminal output suspended by Ctrl/S.
• Hold Screen and No Scroll
  Suspends terminal output until the key is pressed again. The Hold Screen key is available only on an LK201 keyboard, and the No Scroll key is available only on a VT100 keyboard.

This chapter describes how to create and manipulate files locally, and over a TCP/IP or DECnet for OpenVMS network. This chapter includes information about:

• Understanding file names and file specifications
• Using wildcards with file names
• Other file names
• Creating and modifying files
• Displaying the contents of files
• Deleting files
• Protecting files from other users
• Printing files

For additional information, refer to the following:

• The OpenVMS Guide to Extended File Specifications, for information about using extended file names, file specifications, and wildcards in an environment using Extended File Specifications
• The OpenVMS DCL Dictionary and online help, for commands discussed in this chapter
• The OpenVMS System Manager's Manual, for information about accessing remote nodes
• The Digital TCP/IP Services for OpenVMS User's Guide, for information about using TCP/IP user utilities and commands.
• The DECnet for OpenVMS Networking Manual, for information about DECnet networks
• The DECnet-Plus for OpenVMS Introduction and User's Guide, for information about DECnet Phase V networks.

A file is a unit that the OpenVMS operating system uses to store human-readable and machine-readable data. When you create or name a file, you must specify certain information so that the system can locate and identify the file. You do not have to include all the elements of a complete file specification (see Section 4.1.1). However, you must specify enough of the file specification so that, when combined with default components, the system can locate and identify the correct file according to the RMS facility's rules for file specification parsing. Refer to the Guide to OpenVMS File Applications for more information on how RMS applies defaults to partial file specifications.

To override system defaults or to perform file operations over a network, you must provide a complete file specification. A complete file specification has the following format:

The components are as follows:

Use the following rules to specify the elements of a file specification:

• Give the file a name that is meaningful to you. On OpenVMS Alpha and OpenVMS VAX systems with disks of ODS-2 strucutre level, the file name can have up to 39 characters chosen from the letters A to Z (uppercase or lowercase), the numbers 0 to 9, underscores (_), hyphens (-), and dollar signs ($).
• Do not use a hyphen as the first character in the file name because some older versions of OpenVMS do not allow it in all forms of a file specification.
• The file type begins with a period (.). On Alpha and VAX systems with disks of ODS-2 structure level, the file type can have up to 39 characters (including the period), chosen from the letters A through Z (which may be specified in uppercase or lowercase form), the numbers 0 through 9, underscores (_), hyphens (-), and dollar signs ($).
• On OpenVMS Alpha Version 7.2 or later, using ODS-5 structure-level disks, a filename (file name plus file type) may be 255 characters long.
• A version component begins with a semicolon (;) or a period (.) (When the system displays file specifications, it displays a semicolon for the version component.)
• Do not use a directory field to refer to files on magnetic tape. (Directories apply only to files on disks.)
• Include a node name only if your system is part of a network and if the file is on a node other than the one you are logged in to.
• On OpenVMS Alpha and OpenVMS VAX systems with disks of ODS-2 structure level, a UFD (User File Directory) name or a subdirectory name can be 39 characters long and can contain characters chosen from the letters A through Z (which may be specified in uppercase or lowercase form), the numbers 0 through 9, underscores (_), hyphens (-), and dollar signs ($). A subdirectory name beginning with a hyphen is not allowed.
• On OpenVMS Alpha Version 7.2 or later, the sum of the numbers of characters in all of the subdirectories of the directory and root components (not including brackets and separator periods) should not exceed 512. In addition, UFD and subdirectory names have the same constraints as those for the file name, type, and version components, taking into account the fact that directories are stored as files of the form <directory-name>.DIR;1.
• In environments that consist of systems that support extended file specifications and systems that do not, remember that files and directories whose names are beyond the capabilities of the more limited systems will not be accessible from those systems.

For more details, refer to the Guide to OpenVMS File Applications.

With certain commands, if you omit the file type, the system applies a default value. The following table lists some of the more common default file types used by DCL commands:

The following table lists the default file types for some high-level language source programs:

In addition to a file name and file type, every file has a version number. Version numbers are decimal numbers from 1 to 32,767 that differentiate versions of a file. When you create a file, the system assigns it the version number 1.

You can have several versions of the same file. Unless you specify a version number, the system uses the highest existing version number of that file. If you specify the version number 0, the system uses the highest existing version. When you modify a file with a command, application, or text editor (such as EVE) that creates a new version of the file, the file name remains the same but the version number is incremented by one.

Precede version numbers with a semicolon or a period. When the system displays file specifications, it displays a semicolon in front of the file version number.

You can refer to versions of a file in a relative manner by specifying a zero or a negative version number. Specifying zero locates the latest (highest numbered) version of the file. Specifying -1 locates the next-most-recent version, -2 the version before that, and so on. To locate the earliest (lowest numbered) version of a file, specify -0 as the version number. Note that you cannot create files with a version number higher than 32767. If you attempt to create a new file with a version number higher than 32767, you will receive an error message.

The /VERSION_LIMIT qualifier for the CREATE/DIRECTORY, SET DIRECTORY, and SET FILE commands lets you control the number of versions of a file. If you exceed the version limit, the system automatically purges the lowest version file in excess of the limit. For example, if the version limit is 5 and you create the sixth version of a file (ACCOUNTS.DAT;6), the system deletes the first version of the file (ACCOUNTS.DAT;1). To view the version limit on a file, enter the DIRECTORY/FULL command. The version limit is listed in the File attributes: field.

4.1.6 Network Node Names

A node is an individual computing system that is part of a computer network. If your system is part of a network, the node that you access when you log in is your local node. Other nodes in the network are remote nodes. Use a node name when you want to specify a file on a remote node.

A node specification has the following format:

Observe the following rules when entering a node name as part of a file specification:

• Node names can contain 1 to 6 alphanumeric characters and must contain at least one alphabetic character. For example:

  AFTP1
  F2OTR2
  MYNODE

• A node name (with or without an access control string) must always be followed by a double colon (::).
• When you specify a node name, you can include a 0- to 42-character access control string. An access control string contains login information to be sent to the remote node. For more information on access control strings, see Section 4.1.12.
  Note that the required double colon follows the access control string.
• You can use a logical name in place of the node name. For information on logical node names, see Chapter 13.

On OpenVMS systems, you can specify node full names. However, you must have DECnet--Plus software installed for full node names to be recognized.

Valid full node names can contain up to 255 characters and can include any characters except the following:

• Spaces
• Tabs
• The characters: comma (,), quotation marks (" "), slash (/), exclamation point (!), equal sign (=), plus sign (+), at sign (@), apostrophe ('), parentheses (( )), and double colons (::)
• A single colon (:) as the first or last character

If a full node name is enclosed in quotation marks (" "), it can contain any characters except unmatched quotation marks. Note that if there are quotation marks within the node name, the quotation marks must be doubled and the entire string, including the quotation marks, must also be enclosed in quotation marks.

Although the OpenVMS software enforces few rules on the syntax of node names, the actual set of valid node names is constrained by the DECnet software running on your system. For further information on full names, refer to the DECnet--Plus documentation. The syntax rules, including valid character codes, are described in detail in the DECnet--Plus DECdns Management Guide.

In the following example, the entire string is in quotation marks because there are quotation marks in the node name:

"MARY:.UNIVERSITY.""SCIENCE LAB"""

Other examples of valid full node names are:

MYNODE
MASSACHUSETTS:.BUSINESS.YOURNODE
A.B;C

With TCP/IP, unless otherwise stated, whenever you specify a host on a command line, you can use its host name, a fully qualified domain name, or its IP address. The relative name of a host is a simple name that does not include the fully qualified domain name; that is, it does not include one or more periods (.). Refer to the Digital TCP/IP Services for OpenVMS User's Guide for the TCP/IP syntax rules.