Document revision date: 30 March 2001
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OpenVMS DCL Dictionary
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SET SYMBOL

Controls access to local and global symbols in command procedures.

Format

SET SYMBOL

Description

The SET SYMBOL command controls access to local and global symbols in command procedures by treating symbols as undefined. Because all global and local symbols defined in an outer procedure level are accessible to inner procedure levels, it is often necessary to mask these symbols without deleting them.

The SET SYMBOL command also controls whether DCL will attempt to translate the verb string (the first token on the command line) as a symbol before processing the line. The default behavior is that the translation is attempted. The advantage to changing this behavior is that a command procedure will not be affected by outer procedure level environments when invoking a command.

The symbol scoping context is different for local and global symbols. Local symbols are procedure level dependent. Local symbols defined in an outer subroutine level can be read at any inner subroutine level, but they cannot be written to. If you assign a value to a symbol that is local to an outer subroutine level, a new symbol is created at the current subroutine level; however, the symbol in the outer procedure level is not modified.

This means that the SET SYMBOL/SCOPE=NOLOCAL command causes all local symbols defined at an outer procedure level to be inaccessible to the current procedure level and any inner levels. For example, if SET SYMBOL/SCOPE=NOLOCAL was specified at procedure levels 2 and 4, procedure level 2 can read (but not write to) only level 2 local symbols. Level 3 can read (but not write to) level 2 local symbols and can read and write to level 3 local symbols. Level 4 can read and write to only level 4 local symbols.

Global symbols are procedure-level independent. The current global symbol scoping context is applied subsequently to all procedure levels. Specifying the /SCOPE=NOGLOBAL qualifier causes all global symbols to become inaccessible for all subsequent commands until either the /SCOPE=GLOBAL qualifier is specified or the procedure exits to a previous level at which global symbols were accessible. In addition, specifying the /SCOPE=NOGLOBAL qualifier prevents you from creating any new global symbols until the /SCOPE=GLOBAL qualifier is specified.

When you exit a procedure level to return to a previous procedure, the symbol scoping context from the previous level is restored for both local and global symbols.

To display the current symbol scoping state, use the lexical function F$ENVIRONMENT("SYMBOL_SCOPE").

Qualifiers

/ALL (default)

Specifies that the values of the /SCOPE qualifier pertain both to the translation of the first token on a command line and to general symbol substitution.

The /ALL qualifier is incompatible with the /GENERAL or the /VERB qualifier.

/GENERAL

Specifies that the values of the /SCOPE qualifier pertain to the translation of all symbols except the first token on a command line.

The /GENERAL qualifier is incompatible with the /ALL or the /VERB qualifier.

/SCOPE=(keyword,...)

Controls access to local and global symbols. Lets you treat symbols as being undefined. Possible keywords are as follows:
NOLOCAL Causes all local symbols defined in outer procedure levels to be treated as being undefined by the current procedure and by all inner procedure levels.
LOCAL Removes any symbol translation limit set by the current procedure level.
NOGLOBAL Causes all global symbols to be inaccessible to the current procedure level and to all inner procedure levels unless otherwise changed.
GLOBAL Restores access to all global symbols.

/VERB

Specifies that the values of the /SCOPE qualifier pertain to the translation of the first token on a command line as a symbol before processing only. It does not affect general symbol substitution.

Note
Caution must be used if the SET SYMBOL/VERB/SCOPE command is used more than once in a command procedure. Because DCL uses the translation behavior when looking for a label or subroutine, execution may be different running in one mode than in another. Compaq recommends that the SET SYMBOL/VERB/SCOPE command be used once as part of the command procedure setup and left in that mode for the duration of the procedure.

The /VERB qualifier is incompatible with the /ALL or the /GENERAL qualifier.

Examples

#1 

$ SET SYMBOL/SCOPE=NOLOCAL

In this example, all local symbols defined in outer procedure levels are now undefined for the current procedure level and all inner procedure levels.

#2 

$ SET SYMBOL/SCOPE=NOGLOBAL

In this example, all global symbols are now inaccessible to the current procedure level and all inner procedure levels unless otherwise changed.

#3 

$ NOW :== SHOW TIME
$ !
$ NOW
   3-NOV-2001 11:48:58
$ !
$ SET SYMBOL /VERB /SCOPE=NOGLOBAL
$ NOW
%DCL-W-IVVERB, unrecognized command verb-check validity and spelling
 \NOW\
$ !
$ SHOW SYMBOL NOW
  NOW == "SHOW TIME"

This example demonstrates the use of the /VERB qualifier.

The symbol NOW is assigned to the SHOW TIME command. The next line shows the default behavior, where DCL attempts to translate the first string on the command line (NOW). Because NOW translates to the SHOW TIME command, this is used instead of NOW.

The SET SYMBOL command on the next line changes the behavior so that DCL does not attempt a translation. When NOW is subsequently entered, DCL uses the string NOW as the command verb and cannot find it in the command table. This results in the error message.

Notice that the scoping of the verb translation has no effect on general symbol translations, as demonstrated by the SHOW SYMBOL command in the example.

SET TERMINAL

Sets the characteristics of a terminal. Entering a qualifier changes a characteristic; omitting a qualifier leaves the characteristic unchanged.

Format

SET TERMINAL [device-name[:]]

Parameter

device-name[:]

Specifies the device name of the terminal. The default is SYS$COMMAND if that device is a terminal. If the device is not a terminal, an error message is displayed.

Description

The SET TERMINAL command modifies specific terminal characteristics for a particular application or overrides system default characteristics. (These defaults are defined at each installation, based on the most common type of terminal in use.) The default characteristics for terminals are listed in Figure DCLII-2.

The terminal characteristics, local or remote, are determined automatically by the terminal driver for terminals that have the modem characteristic enabled. These characteristics are not affected by the SET TERMINAL command. For example, when you successfully dial in to an OpenVMS system processor, you establish your terminal as remote. When you hang up, the terminal characteristic is set back to local.

The set of terminals supported by the OpenVMS system includes a set of VT100 family terminals that support special DIGITAL ANSI characteristics and escape sequences. For a description of these special characteristics and escape sequences, refer to the OpenVMS I/O User's Reference Manual.

Figure DCLII-2 Default Characteristics for Terminals

Qualifiers

/ADVANCED_VIDEO

/NOADVANCED_VIDEO

Controls whether the terminal has advanced video attributes and is capable of 132-column video. If the terminal width is set to 132 columns and you specify the /ADVANCED_VIDEO qualifier, the terminal page limit is set to 24 lines. If you specify the /NOADVANCED_VIDEO qualifier, the terminal page limit is set to 14 lines.

/ALTYPEAHD

Causes the terminal driver to create a permanent, alternate type-ahead buffer. The system parameter TTY_ALTYPEAHD determines the size of the type-ahead buffer. This specification is effective at your next login and stays in effect until you reboot your VAX computer.

To enable /ALTYPEAHD, you must also set the qualifier /TYPE_AHEAD.

You should specify SETTERMINAL/PERMANENT/ALTYPEAHD in SYS$STARTUP:SYSTARTUP_VMS.COM for those communication lines that require this capability.

To use this feature interactively, specify SET TERMINAL/PERMANENT/ALTYPEAHD. This specification is effective at your next login.

/ANSI_CRT (default)

/NOANSI_CRT

Controls whether the terminal conforms to ANSI CRT programming standards. Because ANSI standards are a proper subset of the DEC_CRT characteristics, the default for all VT100 family terminals is /ANSI_CRT.

/APPLICATION_KEYPAD

Specifies that the keypad is to be set to application keypad mode, which allows you to enter DCL commands defined with the DEFINE/KEY command. By default, the terminal is set to numeric keypad mode.

/AUTOBAUD

/NOAUTOBAUD

Controls whether the terminal baud rate is set when you log in and sets the default terminal speed to 9600. You must press Return two or more times at intervals of at least 1 second for the baud rate to be determined correctly. If you press a key other than Return, the /AUTOBAUD qualifier may detect the wrong baud rate. If this happens, wait for the login procedure to time out before continuing. The /AUTOBAUD qualifier must be used with the /PERMANENT qualifier.

The valid baud rates are as follows: 


 50       150       1800       4800       38400 
 75       300       2000       7200       57600 
110       600       2400       9600       76800 
134      1200       3600      19200      115200

/BLOCK_MODE

/NOBLOCK_MODE

Controls whether block mode transmission, local editing, and field protection are performed.

/BRDCSTMBX

/NOBRDCSTMBX

Controls whether broadcast messages are sent to an associated mailbox if one exists.

/BROADCAST (default)

/NOBROADCAST

Controls whether reception of broadcast messages (such as those issued by MAIL and REPLY) is enabled. Specify the /NOBROADCAST qualifier when you are using a terminal as a noninteractive device or when you do not want special output to be interrupted by messages. Use the SET BROADCAST command to exclude certain types of messages from being broadcast, rather than eliminating all messages.

/COLOR

Sets the ANSI_COLOR terminal characteristic and identifies the terminal as capable of supporting the ANSI color escape sequences.

/COMMSYNC

/NOCOMMSYNC (default)

Allows connection of asynchronous printers and other devices to terminal ports, using standard modem control signals as flow control. Transmission to the device stops if either data set ready (DSR) or clear to send (CTS) EIA modem control signals are dropped. Transmission resumes when both signals are present.

The /COMMSYNC qualifier and the /MODEM qualifier are mutually exclusive.

The COMMSYNC feature has the following limitations:

Caution
The /COMMSYNC qualifier should never be set on a line with a modem that is intended for interactive use. The qualifier disables the modem terminal characteristic that disconnects a user process from the terminal line in case of a modem phone line failure. With the /COMMSYNC qualifier enabled, the next call on the terminal line could be attached to the previous user's process. Security administrators should be aware that the characteristic should not be used on interactive terminal ports. In addition, the /COMMSYNC qualifier is not supported on a port connected to a LAT line.

/CRFILL[=fill-count]

Generates the specified number of null characters after each carriage return before transmitting the next meaningful character (to ensure that the terminal is ready for reception). The value must be an integer in the range 0 to 9. The default is the /CRFILL=0 qualifier.

/DEC_CRT[=(value1,value2,value3)]

/NODEC_CRT[=(value1,value2,value3)]

Controls whether the terminal conforms to DIGITAL VT100-, VT200-, VT300-, VT400-, or VT500-family standards and supports the minimum standards, including the additional DIGITAL escape sequences.

You can specify one of the following values:
1 (default) Requests that the DEC_CRT terminal characteristic be set.
2 Requests that the DEC_CRT2 terminal characteristic be set.
3 Requests that the DEC_CRT3 terminal characteristic be set. A level 3 terminal supports the following additional features:
  • A status line (line 25, at the bottom of the screen)
  • The ISO Latin1 character set
  • Terminal state interrogation (describes what state your terminal is in)
4 Requests that the DEC_CRT4 terminal characteristic be set. A level 4 terminal supports the following additional features:
  • Extended keyboard
  • Key position mode
  • Secure reset
  • Novice mode
  • Selective erase
  • On-line transaction processing (OLTP) features:
    • Page memory
    • Rectangular editing
    • Text macros
    • Data integrity reports

Note that DEC_CRT2, DEC_CRT3, and DEC_CRT4 are supersets of DEC_CRT. Clearing DEC_CRT causes DEC_CRT2, DEC_CRT3, and DEC_CRT4 to be cleared. Similarly, setting DEC_CRT4 causes all subsets of DEC_CRT4 (including ANSI_CRT) to be set.

/DEVICE_TYPE=terminal-type

Informs the system of the terminal type and sets characteristics according to the device type specified. You can specify any of the following terminal types:
UNKNOWN
FT1--FT8
LA12
LA34
LA36
LA38
LA100
LA120
LA210
LN01K
LN03
LQP02
PRO_SERIES
VT05
VT52
VT55
VT100
VT101
VT102
VT105
VT125
VT131
VT132
VT173
VT200
VT300
VT400
VT500

The default characteristics for the VT100-, VT102-, and VT125-series terminals are as follows:
/ADVANCEDVIDEO /NOALTYPEAHD 1 /ANSI_CRT
/NOAUTOBAUD /NOBLOCK_MODE /NOBRDCSTMBX
/BROADCAST /CRFILL=0 /ECHO
/NOEIGHT_BIT /NOESCAPE /NOFORM
/FULLDUP /NOHOSTSYNC /LFFILL=0
/LOWERCASE /NODMA /PAGE=24
/NOPARITY /NOPASTHRU /NOREADSYN
/SPEED=9600 /TAB /TTSYNC
/TYPE_AHEAD /WIDTH=80 /WRAP

1This is the default characteristic set by the system and is not a valid qualifier for your use.

The terminal types and characteristics that can be set are listed in Figure DCLII-2.

/DIALUP

/NODIALUP (default)

Controls whether the terminal is a dialup terminal.

/DISCONNECT

/NODISCONNECT (default)

Controls whether the process connected to this terminal is disconnected if the line detects a hangup. The /DISCONNECT qualifier is valid only when the /PERMANENT qualifier is specified.

/DISMISS

/NODISMISS (default)

Controls whether the terminal driver ignores data that causes a parity error (instead of terminating the currently outstanding I/O with an error status).

/DMA

/NODMA

Controls whether direct memory access (DMA) mode is used on a controller that supports this feature.

/ECHO (default)

/NOECHO

Controls whether the terminal displays the input it receives. With the /NOECHO qualifier, the terminal displays only system or user application output, or both.

/EDIT_MODE

/NOEDIT_MODE

Controls whether the terminal can perform ANSI-defined advanced editing functions.

/EIGHT_BIT

/NOEIGHT_BIT

Controls whether the terminal uses the 8-bit ASCII protocol rather than the 7-bit ASCII protocol. You can use the Terminal Fallback Facility (TFF) to set the 8-bit characteristic on terminals. If the terminal you specify has the TFF enabled, the /EIGHT_BIT qualifier has no effect. For more information on terminal fallback, refer to the OpenVMS Terminal Fallback Utility Manual (available on the Documentation CD-ROM).

/ESCAPE

/NOESCAPE (default)

Controls whether escape sequences are validated.

/FALLBACK

/NOFALLBACK

Controls whether the 8-bit DEC Multinational character set characters are displayed on the terminal in their 7-bit representation. The default depends on the /EIGHTBIT setting of the terminal. If the OpenVMS Terminal Fallback Facility (TFF) is enabled, it activates the default character conversion tables for the named terminal. For more information, refer to the OpenVMS Terminal Fallback Utility Manual (available on the Documentation CD-ROM). If TFF is not enabled on your system, the /FALLBACK qualifier has no effect and no error message is displayed.

/FORM

/NOFORM

Controls whether a form feed is transmitted rather than translated into multiple line feeds.

/FRAME=n

Specifies the number of data bits that the terminal driver expects for every character that is input or output. The value of n can be from 5 to 8. The default value depends on the settings for the terminal established by the /PARITY and /EIGHTBIT qualifiers.

/FULLDUP (default)

/NOFULLDUP

Controls whether the terminal operates in full-duplex mode. The /FULLDUP qualifier is equivalent to the /NOHALFDUP qualifier.

/HALFDUP

/NOHALFDUP (default)

Controls whether the terminal operates in half-duplex mode. The /HALFDUP qualifier is equivalent to the /NOFULLDUP qualifier.

/HANGUP

/NOHANGUP (default)

May require LOG_IO (logical I/O) or PHY_IO (physical I/O) privilege depending on system generation parameter settings.

Controls whether the terminal modem is hung up when you log out.

/HARDCOPY

/NOHARDCOPY

Controls whether the device is established as a hardcopy terminal and outputs a backslash (\) when the Delete key is pressed. The /HARDCOPY qualifier is equivalent to the /NOSCOPE qualifier.

/HOSTSYNC

/NOHOSTSYNC (default)

Controls whether system transmission from the terminal is stopped (by generating a Ctrl/S) when the input buffer is full and resumed (by generating a Ctrl/Q) when the input buffer is empty.

/INQUIRE

Sets the device type when the /INQUIRE qualifier is specified and the DEC_CRT characteristic is set. The SET TERMINAL command reads the current screen size from the terminal and sets the corresponding page length and page width values appropriately. The default device type is UNKNOWN. Works only on DIGITAL terminals, and not on LA36 or VT05 terminals. Some VT100 family terminals, including the VT101 and VT105, return a VT100 type response. LA38 terminals respond as LA43 terminals.

Note
The SET TERMINAL/INQUIRE command works correctly on DIGITAL supplied VT100 and later terminals. Some personal computer terminal emulators may not work correctly, because they do not correctly emulate all VT100 escape sequences. Compaq recommends that users who experience problems with these terminal emulators contact the terminal emulator supplier.

You can include the SET TERMINAL/INQUIRE command in your LOGIN.COM file to detect the terminal type automatically.

If you specify /INQUIRE=OLD, OpenVMS sets the terminal window to 24 lines by 80 columns and ignores the real terminal size. (This is the behavior of the SET TERMINAL/INQUIRE command prior to OpenVMS Version 6.2.)

Caution
This qualifier clears the type-ahead buffer. If the response sequence is unrecognized, no action message or error message is displayed. The /INQUIRE qualifier should be used only on DIGITAL terminals; however, the LA36 and VT05 terminals do not support this feature.

/INSERT

Sets the terminal to insert mode. This feature allows you to insert characters when editing command lines. The default mode is overstrike, which allows you to type over the current character when editing a command line. Press Ctrl/A to switch from one mode to the other.

/LFFILL[=fill-count]

Transmits to the terminal the specified number of null characters after each line feed before transmitting the next meaningful character (to ensure that the terminal is ready for reception). The value must be an integer in the range 0 to 9. The default is installation dependent. See Figure DCLII-2 for a list of default terminal characteristics.

/LINE_EDITING

/NOLINE_EDITING

Controls whether advanced line-editing features are enabled for editing command lines: pressing Return and pressing Ctrl/Z are recognized as line terminators, as are escape sequences.

/LOCAL_ECHO

/NOLOCAL_ECHO (default)

Controls whether the terminal echoes characters locally (rather than the host echoing them) for command level terminal functions. (Do not use the /LOCAL_ECHO qualifier with utilities that require control over echoing, such as line editing or EDT's screen mode.)

Caution
When logging in to terminals with the LOCAL_ECHO characteristic, the OpenVMS system has no control over the echoing of passwords.

/LOWERCASE

/NOLOWERCASE

Controls whether lowercase characters are passed to the terminal. The /NOLOWERCASE qualifier translates all input to uppercase. The /LOWERCASE qualifier is equivalent to the /NOUPPERCASE qualifier.

/MANUAL

Indicates manual switching of terminal lines to dynamic asynchronous DDCMP lines when your local terminal emulator does not support automatic switching. The /MANUAL qualifier should be specified with the /PROTOCOL=DDCMP and /SWITCH=DECNET qualifiers.

/MODEM

/NOMODEM

Specifies whether the terminal is connected to a modem or a cable that supplies standard EIA modem control signals. If your terminal has the MODEM characteristic, entering SET TERMINAL/NOMODEM automatically logs you out. The /MODEM qualifier and the /COMMSYNC qualifier are mutually exclusive.

/NUMERIC_KEYPAD (default)

Specifies whether the keys of the numeric keypad are used to type numbers and punctuation marks (/NUMERIC_KEYPAD) or to enter DCL commands defined with the DEFINE/KEY command (/APPLICATION_KEYPAD).

/OVERSTRIKE (default)

Sets the terminal to overstrike mode. This feature allows you to type over the current character when you are editing a command line. Set your terminal to insert mode if you want to insert characters when editing command lines. Press Ctrl/A to switch from one mode to the other.

/PAGE[=lines-per-page]

Specifies the number of print lines between perforations for hardcopy terminals. (When the terminal reads a form feed, it advances the paper to the next perforation.) The value of the lines-per-page parameter can be from 0 to 255 and defaults to 0 (which treats a form feed as a line feed).

/PARITY[=option]

/NOPARITY (default)

Controls whether the terminal passes data with only odd or even parity, where option equals ODD or EVEN. If you specify the /PARITY qualifier without an option, the value defaults to EVEN.

/PASTHRU

/NOPASTHRU (default)

Controls whether the terminal passes all data (including tabs, carriage returns, line feeds, and control characters) to an application program as binary data. The setting of /TTSYNC is allowed.

Make sure that you spell both these qualifiers exactly as they appear in the text.

/PERMANENT

Requires LOG_IO (logical I/O) or PHY_IO (physical I/O) privilege.

Sets characteristics on a permanent basis, that is, over terminal sessions; however, the characteristics revert to their initial values if the system is halted and restarted. Use in a system startup file to establish characteristics for all terminals on the system.

/PRINTER_PORT

/NOPRINTER_PORT

Specifies whether the terminal has a printer port (an attribute not set by the SET TERMINAL/INQUIRE command). The default is installation dependent. See Figure DCLII-2 for a list of default terminal characteristics.

/PROTOCOL=DDCMP

/PROTOCOL=NONE (default)

On VAX, controls whether the terminal port specified is changed into an asynchronous DDCMP line. The /PROTOCOL=NONE qualifier changes an asynchronous DDCMP line back into a terminal line. Note that /PROTOCOL=DDCMP is a permanent characteristic; therefore, the /PERMANENT qualifier is not required.

/READSYNC

/NOREADSYNC (default)

Controls whether the terminal uses the Ctrl/S and Ctrl/Q functions to synchronize data transmitted from the terminal.

Caution
SET TERMINAL/READSYNC should not be used on LAT terminal lines. Setting this characteristic may cause unexpected results.

The default is the /NOREADSYNC qualifier; the system does not use the Ctrl/S and Ctrl/Q functions to control reads to the terminal. The /READSYNC qualifier is useful for certain classes of terminals that demand synchronization or for special-purpose terminal lines where data synchronization is appropriate.

/REGIS

/NOREGIS

Specifies whether the terminal understands ReGIS graphic commands.

/SCOPE

/NOSCOPE

Controls whether the device is established as a video terminal. The /SCOPE qualifier is equivalent to the /NOHARDCOPY qualifier.

/SECURE_SERVER

/NOSECURE_SERVER (default)

Requires either LOG_IO (logical I/O) or PHY_IO (physical I/O) privilege.

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