HP OpenVMS Systems Documentation

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

$ 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.

$ 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.

$ 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.

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:

• Cannot be used on LAT ports
• Can only be used on ports with full modem control
• Should not be used in conjunction with Xon/Xoff flow control (the port may hang)

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

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

/DIALUP

/NODIALUP (default)

/DISCONNECT

/NODISCONNECT (default)

/DISMISS

/NODISMISS (default)

/DMA

/NODMA

/ECHO (default)

/NOECHO

/EDIT_MODE

/NOEDIT_MODE

/EIGHT_BIT

/NOEIGHT_BIT

/ESCAPE

/NOESCAPE (default)

/FALLBACK

/NOFALLBACK

/FORM

/NOFORM

/FRAME=n

/FULLDUP (default)

/NOFULLDUP

/HALFDUP

/NOHALFDUP (default)

/HANGUP

/NOHANGUP (default)

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

/HARDCOPY

/NOHARDCOPY

/HOSTSYNC

/NOHOSTSYNC (default)

/INQUIRE

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.)

/INSERT

/LFFILL[=fill-count]

/LINE_EDITING

/NOLINE_EDITING

/LOCAL_ECHO

/NOLOCAL_ECHO (default)

/LOWERCASE

/NOLOWERCASE

/MANUAL

/MODEM

/NOMODEM

/NUMERIC_KEYPAD (default)

/OVERSTRIKE (default)

/PAGE[=lines-per-page]

/PARITY[=option]

/NOPARITY (default)

/PASTHRU

/NOPASTHRU (default)

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

/PERMANENT

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

/PROTOCOL=DDCMP

/PROTOCOL=NONE (default)

/READSYNC

/NOREADSYNC (default)

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

/SCOPE

/NOSCOPE

/SECURE_SERVER

/NOSECURE_SERVER (default)