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OpenVMS DCL Dictionary

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Controls whether the Break key on the terminal logs out the current process (except on a virtual terminal). With the /SECURE_SERVER qualifier in effect, pressing the Break key when there is no current process initiates the login sequence. With the /NOSECURE_SERVER qualifier in effect, the break is ignored.

On terminals with the AUTOBAUD and SECURE_SERVER characteristics, pressing the Break key disconnects the current process, but is not required to start a new login sequence. However, when the NOAUTOBAUD characteristic is set, the SECURE_SERVER characteristic requires a break to initiate a new login sequence.



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

Controls whether the /SPEED qualifier can be used to change the terminal speed.



Specifies whether the terminal is capable of displaying graphics using the sixel graphics protocol. The default is device dependent. For a list of default terminal characteristics, see Figure DCLII-2.



Specifies whether the terminal is capable of loading a user-defined character set. The default is device dependent. See Figure DCLII-2 for a list of default terminal characteristics.


Sets the baud rate at which the terminal receives and transmits data. If the input and output rates are the same, specify /SPEED=rate.

Not all terminals support different input and output baud rates. For specific information on baud rates for your terminal, consult the manual for that terminal.

The default transmission rates are installation dependent.

The valid values for input and output 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


On VAX, causes the terminal lines at each node to be switched to dynamic asynchronous DDCMP lines, when specified with the /PROTOCOL=DDCMP qualifier. Note that /SWITCH=DECNET is a permanent characteristic; therefore, the /PERMANENT qualifier is not required.



Requires LOG_IO (logical I/O) privilege.

Determines whether the terminal requires that a system password be entered before the Username: prompt.



Controls whether tab characters are converted to multiple blanks. The /NOTAB qualifier expands all tab characters to blanks and assumes tab stops at 8-character intervals. The default is device dependent. For a list of default terminal characteristics, see Figure DCLII-2.

/TTSYNC (default)


Controls whether transmitting to the terminal is stopped when Ctrl/S is pressed and resumes transmission when Ctrl/Q is pressed.

/TYPE_AHEAD (default)


Controls whether the terminal accepts unsolicited input to the limit of the type-ahead buffer.

When you specify the /NOTYPE_AHEAD qualifier, the terminal accepts input only when a program or the system issues a read to the terminal, such as for user input at the DCL prompt ($). When you specify the /TYPE_AHEAD qualifier, the amount of data that can be accepted is governed by the size of the type-ahead buffer. That size is determined by system generation parameters.


Specifies a terminal type that is unknown to the system, which then uses the default terminal characteristics for unknown terminals. For a summary of the settings, see Figure DCLII-2.



Controls whether lowercase characters are translated to uppercase. The /UPPERCASE qualifier is equivalent to the /NOLOWERCASE qualifier.


Specifies the maximum characters per line. This value must be an integer in the range 1 to 511. With the /WRAP qualifier, the terminal generates a carriage return and line feed when the width specification is reached.

If the specified width on an ANSI terminal is 132, the screen is set to 132-character mode. If the terminal does not have advanced video option (AVO), the page length limit is set to 14 lines.

/WRAP (default)


Controls whether a carriage return and line feed are generated when the value of the /WIDTH qualifier is reached.




In this example, the SET TERMINAL command establishes the current terminal as a VT102 terminal and sets the default characteristics for that terminal type.




In this example, the first SET TERMINAL command indicates that the width of terminal lines is 132 characters and that the size of each page is 60 lines. The /NOBROADCAST qualifier disables the reception of broadcast messages while the terminal is printing the file MEMO.DOC. The next SET TERMINAL command restores the terminal to its default state.


Resets the system clock, which is used as a timer to record intervals between various internal events and as a source clock for displaying the time of day.

Requires both OPER (operator) and LOG_IO (logical I/O) privileges.


SET TIME [=time]



Specifies a date in the format day-month-year, or a time in the format hour:minute:second.hundredth, or both. These fields accept the following values:
Field Type Values
Day Integer 1 to 31
Year Integer 1858 to 9999 - VAX only
Year Integer 1957 to 2056 - Alpha only
Hour Integer 0 to 23
Minute Integer 0 to 59
Second Integer 0 to 59
Hundredth Integer 0 to 99

The hyphens (-), colons (:), and period (.) are required delimiters. Separate the date and time, when both are specified, with a colon. The syntax is sometimes specified as follows:

[dd-mmm-yyyy[:]] [hh:mm:ss.cc]

Alpha systems also allow a 2-digit year format:

[dd-mmm-yy[:]] [hh:mm:ss.cc]

The century applied to the 2-digit year format is determined by the corresponding year in the supported Alpha date range (1957-2056).

If the explicit time value is not specified, the interval system clock is automatically reset according to the time-of-year clock.

Note that the time-of-year clock is optional for some VAX processors. For further information about the time-of-year clock, refer to the hardware documentation for your computer.


Alpha systems maintain system time during power failures and system down time. When a system is booted, if the time is known to be earlier than the time value of the last time modification, or greater than five years in the future, you are prompted to enter the time at the console prompt.


Resets the system clock, which is used as a timer to record intervals between various internal events and as a source clock for displaying the time of day.


The SET TIME command will not work if there is a time service available on your system or OpenVMS Cluster.



Requires OPER and LOG_IO privilege, and in an OpenVMS Cluster environment, SYSLCK privilege.

Sets the time on all nodes in a cluster to the same system time. The format of the SET TIME /CLUSTER command is the following:





$ SET TIME=14-DEC-2001:19:31:0.0

The SET TIME command in this example sets the date and time to December 14, 2001, 7:31 P.M.


14-DEC-2001 03:21:27.53

The SET TIME command in this example sets the system time according to the time-of-year clock. The SHOW TIME command requests a display of the current time.


$ SET TIME=14-DEC-2001:15:31:0.0/CLUSTER

This example sets the date and time to December 14, 2001, 3:31 P.M. on all nodes in the cluster where the command was entered.


Controls whether command lines and data lines in command procedures are displayed at the terminal or are printed in a batch job log. The information displayed by the SET VERIFY command can help you in debugging command procedures.






Specifies one or both types of verification. Procedure verification causes each DCL command line in a command procedure to be written to the output device. Image verification causes data lines (input data that is included as part of the SYS$INPUT input stream) to be written to the output device.

By default, both types of verification are set or cleared with SET VERIFY and SET NOVERIFY. If you specify only one keyword, the other is not affected. If you specify only one keyword, omit the parentheses.


By default, the SET VERIFY and SET NOVERIFY commands set or clear both types of verification. The default setting for command procedures executed interactively is SET NOVERIFY. System responses and error messages are, however, always displayed. The default for batch jobs is SET VERIFY.

If you use the SET VERIFY command to override the default setting, the system displays each command and data line in the command procedure as it reads it. When verification is in effect, the command interpreter displays each command line after it has completed initial scanning and before the command is parsed and executed. You see the results of symbol substitution performed during scanning, but not the results of symbol substitution performed during parsing and evaluation.

When you change the verification setting, the new setting remains in effect for all command procedures that you subsequently execute.

A file must have read (R) access to allow the SET VERIFY command to set verification.




In this example, procedure verification is turned on. If image verification was on, it remains on; if image verification was off, it remains off.



Procedure and image verification are turned on at the beginning of the command procedure so that the system displays all the command and data lines in the procedure as it reads them. At the end of the procedure, the SET NOVERIFY command restores the system default (no procedure or image verification).


$ SET PREFIX "(!%T)"


This command procedure uses the F$ENVIRONMENT lexical function to save the current procedure and image verification setting, as well as the current verification prefix string. The SET PREFIX command sets the verification prefix to be used in the current command procedure. It uses an FAO control string to produce the time each command is read by the command interpreter (DCL), surrounded by parentheses. Then the SET VERIFY command turns on both procedure and image verification. Subsequently, the F$VERIFY lexical function is used to restore the original verification settings. The SET PREFIX command returns the verification prefix to its previous setting. Note how the symbol HOLD_PREFIX is used in the SET PREFIX command. This preserves casing and special characters in the stored string.




In this example, the SET VERIFY command turns procedure and image verification on. When the command procedure TEST.COM is executed interactively, the command lines and the data lines for the program AVERAGE are displayed on the terminal. The data lines were entered in the command procedure on lines that did not begin with the DCL prompt.


$ COUNT = 1


When this command procedure is executed interactively, the SET VERIFY command causes the command and data lines to be displayed. Symbols that are substituted during the first phase of symbol substitution (such as 'COUNT') are displayed by the SET VERIFY command, but other symbols are not. The following lines are displayed when this procedure is executed interactively:

$ COUNT = 1
$ IF P1 .NES. "" THEN GOTO &P1

Although these values are not displayed, the value for P1 is substituted during the third phase of symbol substitution, and the value for &P1 is substituted during the second phase.


Changes the characteristics of one or more mounted Files-11 volumes. The SET VOLUME command affects only the node on which the command is issued, and will not affect any other nodes, even when a volume is mounted on multiple nodes in an OpenVMS Cluster configuration.

If you are not the owner of the volume, requires control access to the volume.


SET VOLUME device-name[:][,...]



Specifies the name of one or more mounted Files-11 volumes.



Requires OPER (operator) privilege.

Specifies the number of directories to be maintained in system space for ready access. You can specify a value n in the range of 0 to 255. If you specify the qualifier /ACCESSED and omit the number of directories, a default value of 3 is used. If you specify a value greater than the current value, the new value is effective immediately; otherwise, the new value is not effective until the next time the volume is mounted.


Defines a default for data check operations following all read and write operations to the specified volume. (If you do not specify the /DATA_CHECK qualifier, no checks are made.) Possible keywords are as follows:
READ Performs checks following all read operations.
WRITE Performs checks following all write operations (default).



Determines whether the space occupied by a file is overwritten with a system-specified pattern when a file on the volume is deleted.


Specifies the number of blocks to be used as a default extension size for all files on the volume. You can specify a value n in the range of 0 to 65,535. If you specify the /EXTENSION qualifier without specifying a value, a default value of 0 (the OpenVMS RMS default) is used.

For example, during an update operation, the extension default is used when a file increases to a size greater than its initial default allocation.


Sets the default protection to be applied to all files on the specified disk volume. Specify the ownership parameter as system (S), owner (O), group (G), or world (W) and the access parameter as read (R), write (W), execute (E), or delete (D). A null access specification means no access.


This attribute is not used while the volume is in use on an OpenVMS system, but the attribute is provided to control the process use of the volume on RSX-11M systems. The OpenVMS system always uses the default file protection; the protection can be changed with the DCL command SET PROTECTION/DEFAULT.



Determines whether the file highwater mark (FHM) volume attribute is set. The FHM attribute guarantees that a user cannot read data that was not written by the user. Applies to Files-11 On-Disk Structure Level 2 (ODS-2) and 5 (ODS-5) volumes only.


Specifies a 1- to 12-character ANSI name to be encoded on the volume. The specified label remains in effect until it is changed explicitly; dismounting the volume does not affect the label. Compaq strongly recommends that a volume label should consist only of alphanumeric characters, dollar signs ($), underscores (_), and hyphens (-).

If you change the volume label on an OpenVMS system disk, you should also update the POLYCENTER Software Installation utility database. To accomplish this, use the PRODUCT REGISTER VOLUME command to replace the old volume label with the new volume label.


Changing the volume label does not change other structures that used the original volume label. For example, the DISK$labelname logical is not changed nor is the device-lock name that is kept internally by OpenVMS. As a result, if you attempt to access another disk that has the same volume label as the original volume of this device, you may get error messages such as the following: "%MOUNT-F-VOLALRMNT, another volume of same label already mounted".

Compaq recommends that, if you change a disk volume label, you also dismount and remount the disk on all nodes in the cluster so that the names and locks are consistent.


/NOLOG (default)

Determines whether the volume specification of each volume is displayed after the modification.



Determines whether mount verification is enabled. Mount verification prevents interruption to user input/output operations and notifies the operator of problems with the disk.


Sets the owner user identification code (UIC) of the volume to the specified UIC. The default UIC is that of the current process. Brackets ([]) are required around the UIC. Specify the UIC by using standard UIC format as described in the OpenVMS Guide to System Security.


Specifies the protection to be applied to the volume. The following rules apply:
  • Specify the ownership parameter as system (S), owner (O), group (G), or world (W).
  • Specify the access parameter as read (R), write (W), create (C), or delete (D).

The default protection is all types of access by all categories of user.


Recovers caching limits for a volume that was dismounted improperly. If a disk volume was dismounted improperly (such as during a system failure), and was then remounted with the MOUNT/NOREBUILD command, you can use SET VOLUME/REBUILD to recover the caching that was in effect at the time of the dismount. The FORCE option forces the disk to be rebuilt unconditionally, thus updating the free block count in the disk volume's lock value block.


Specifies the minimum and maximum retention times to be used by the file system to determine the expiration date for files on the volume. When a file is created, its expiration date is set to the current time plus the maximum time. Each time the file is accessed, the current time is added to the minimum time. If the sum is greater than the expiration date, a new expiration date is computed.

If you omit the maximum value, a default value that is the smaller of (2 x min) or (min + 7) days is used. For example, /RETENTION=3- is the same as /RETENTION=(3-,6-), while /RETENTION=10- is the same as /RETENTION=(10-,17-).

The command SET VOLUME/RETENTION=0 disables retention times on the volume.


Sets the structure level of the volume. Use the value 5 to set the volume to ODS-5.

When the /STRUCTURE_LEVEL qualifier is used with other qualifiers, the volume structure level is set prior to the other qualifiers being performed.

You cannot use the SET VOLUME command to change a volume from ODS-5 to ODS-2. To reset a volume to ODS-2, refer to instructions in the OpenVMS Guide to Extended File Specifications.


Compaq does not support creating the system disk as (or changing it to) an ODS-5 volume.

Refer to the OpenVMS Guide to Extended File Specifications for further information.



Enables the processing of subsystem ACEs. Requires the SECURITY privilege. By default, the disk from which you boot has protected subsystems enabled but other disks do not. For further details on subsystems, refer to the OpenVMS Guide to System Security.

/UNLOAD (default)


Specifies whether the volume is unloaded (spun down) when the DCL command DISMOUNT is entered.


Specifies a user name of up to 12 alphanumeric characters to be recorded on the volume. The default name is the current process user name.


Specifies the number of mapping pointers to be allocated for file windows. The value of n can be from 7 to 80; the default value is 7.



This qualifier only affects applications such as PATHWORKS that can request deferred writes to file headers. You use it to control whether these applications can use the deferred write feature.

Use /NOWRITETHROUGH to allow these applications to use the deferred write feature. When one of these applications explicitly requests a deferred write when updating a file header, control returns to the application when the I/O request has been queued; the application does not have to wait until the data is on disk.

Note that although the SHOW DEVICES/FULL command shows the volume status as write-back caching enabled, the extended file cache (XFC) will still be in write-through mode.

Use /WRITETHROUGH to disable the deferred write feature, so that no applications can use it. The SHOW DEVICES/FULL command shows the volume status as write-through caching enabled.

The deferred write feature is not available on Files-11 ODS-1 volumes.




The SET VOLUME command in this example requests that data checks be performed following all read and write operations to DBC5.



The SET VOLUME command in this example sets the default protection to be applied to all files created on volume DBC5. System (S) and owner (O) are granted all types of access; group (G) and world (W) are permitted only to read and execute files on DBC5.



The SET VOLUME command in this example encodes the label LICENSES on the volume DBC5. Note that if characters in labels are entered in lowercase, they are changed to uppercase by the /LABEL qualifier.



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