OpenVMS User's Manual

Once you set the quota for a table, you cannot change it. If the table runs out of room, use the DEASSIGN command to delete old logical names. This frees space for your new logical names.

13.5.16 Example

In the following example, the logical name table ABC is created and is given a quota of 500 bytes:

$ CREATE/NAME_TABLE/QUOTA=500 ABC

The job logical name table is a shareable table. The quota for a job logical name table is established when the table is created. The quota is determined by one or more of the following criteria:

• The JTQUOTA value established for the user in the system user authorization file SYSUAF.DAT (if the first image activated by the process was the system image LOGINOUT).
• The PQL$_JTQUOTA quota list value specified in the call to the Create Process ($CREPRC) system service.
• The /JOB_TABLE_QUOTA qualifier value on the RUN command used to create the detached process.
• The SYSGEN parameter PQL_DJTQUOTA (if none of the preceding conditions applies). The standard default value for this parameter is 1024 bytes; however, the system manager can change it. The System Generation utility (SYSGEN) can be used to display and set the values of the parameters PQL_DJTQUOTA (default job logical name table quota) and PQL_MJTQUOTA (minimum job logical name table quota).

A quota value of 0 for a job logical name table means there is no quota. For all practical purposes, the quota is unlimited.

13.5.18 Using Logical Name Directory Tables

When you enter a logical name as part of a command line, the system translates the logical name by searching the logical name tables in a certain order. The system stores information about existing logical name tables and the order in which they are searched in two logical name directory tables:

• LNM$PROCESS_DIRECTORY, which is a process-private directory
• LNM$SYSTEM_DIRECTORY, which is a shareable directory

There is only one shareable directory for each system but each process has its own process-private directory. Both directories contain logical names that translate iteratively to table names. All logical name tables and any logical names that translate to tables are kept in these directories.

13.6 Process Directory Table LNM$PROCESS_DIRECTORY

Within each logical name table, the system defines some logical names for you. This section describes each table and its system-defined logical names in the process directory table LNM$PROCESS_DIRECTORY. Note that the logical names SYS$INPUT, SYS$OUTPUT, SYS$ERROR, and SYS$COMMAND refer to process-permanent files (files that remain open for the life of the process). For more information on process-permanent files, see Section 13.10.)

13.6.1 LNM$GROUP

LNM$GROUP is a logical name that is defined as LNM$GROUP_xxx, where xxx represents your group number. LNM$GROUP_xxx is the logical name table used by your UIC group. The table LNM$GROUP_xxx is cataloged in the system directory table. Therefore, LNM$GROUP is a logical name that translates iteratively to the name of your group logical name table.

13.6.2 LNM$JOB

LNM$JOB is a logical name that is defined as LNM$JOB_xxx, where xxx represents a number unique to your job tree. LNM$JOB_xxx is the logical name table used by your job. The table LNM$JOB_xxx is cataloged in the system directory table. Therefore, LNM$JOB is a logical name that translates iteratively to the name of your job logical name table.

13.6.3 LNM$PROCESS

LNM$PROCESS is a logical name that translates iteratively to LNM$PROCESS_TABLE, which is the name of your process logical name table.

13.6.4 LNM$PROCESS_DIRECTORY

LNM$PROCESS_DIRECTORY is the name of your process directory logical name table.

13.6.5 LNM$PROCESS_TABLE (Process Table)

LNM$PROCESS_TABLE is the name of your process logical name table, which is available only to your process and any subsequent subprocesses. By default, the table contains the following logical names:

• SYS$COMMAND
  The initial file (usually your terminal) from which DCL reads input. A file from which DCL reads input is called an input stream. The command interpreter uses SYS$COMMAND to "remember" the original input stream.
• SYS$DISK
  The default device established at login or changed by the SET DEFAULT command.
• SYS$ERROR
  The default device or file to which DCL writes system error messages generated by warnings, errors, and severe errors.
• SYS$INPUT
  The default file from which DCL reads input.
• SYS$NET
  The source process that invokes a target process in DECnet for OpenVMS task-to-task communication. When opened by the target process, SYS$NET represents the logical link over which that process can exchange data with its partner. SYS$NET is defined only during task-to-task communication.
• SYS$OUTPUT
  The default file (usually your terminal) to which DCL writes output. A file to which DCL writes output is called an output stream.
• TT
  The default device name for terminals.

The job table contains logical names that are available to all processes in your job tree. There is one job table for each job tree in the system.

The system places logical names created for mounted disks, mounted tapes, and temporary mailboxes in the job logical name table. In addition, the system creates the following logical names:

• SYS$LOGIN
  Your default device and directory when you log in.
• SYS$LOGIN_DEVICE
  Your default device when you log in.
• SYS$REM_ID
  For jobs initiated through a DECnet for OpenVMS network connection, the identification of the process on the remote node from which the job was originated. On an OpenVMS operating system, if proxy logins are enabled, this identification is the process's user name; or if proxy logins are not enabled, this is the process identification (PID) number. (Proxy logins to proxy accounts allow users to access files across the network without specifying an access control string.)
• SYS$REM_NODE
  For jobs initiated through a DECnet for OpenVMS network connection, the name of the remote node from which the job was originated.
• SYS$SCRATCH
  Default device and directory to which temporary files are written.

This section describes each table and its system-defined logical names in the system directory table LNM$SYSTEM_DIRECTORY.

13.7.1 LNM$DCL_LOGICAL

LNM$DCL_LOGICAL is a logical name defined as LNM$FILE_DEV. Translates iteratively into the list of logical name tables searched and displayed by the SHOW LOGICAL command, the SHOW TRANSLATION command, and the F$TRNLNM lexical function. By default, these commands search and display the process, job, group, and system logical name tables, in that order.

13.7.2 LNM$DIRECTORIES

LNM$DIRECTORIES is a logical name defined as LNM$PROCESS_DIRECTORY and LNM$SYSTEM_DIRECTORY.

13.7.3 LNM$FILE_DEV

LNM$FILE_DEV is a logical name defined as the list of logical name tables searched by the system when processing a file specification. Defined as LNM$PROCESS, LNM$JOB, LNM$GROUP, and LNM$SYSTEM so the system searches the process, job, group, and system logical name tables, in that order.

13.7.4 LNM$GROUP_xxx (Group Table)

The group table contains logical names that are available to all users with the same user identification code (UIC) group number. The group table is named LNM$GROUP_xxx, where xxx represents your UIC group number. Use the logical name LNM$GROUP to refer to your group table. Every group on the system has a corresponding group logical name table.

13.7.5 LNM$JOB_xxx

LNM$JOB_xxx is a job logical name table, where xxx is a number unique to this job tree. There is an LNM$JOB_xxx logical name table for each job in the system.

13.7.6 LNM$PERMANENT_MAILBOX

LNM$PERMANENT_MAILBOX is a logical name that is defined as LNM$SYSTEM. Logical names associated with permanent mailboxes are entered in the logical name table to which the logical name LNM$PERMANENT_MAILBOX iteratively translates.

13.7.7 LNM$SYSTEM

LNM$SYSTEM is a logical name that translates iteratively to LNM$SYSTEM_TABLE.

13.7.8 LNM$SYSTEM_TABLE (System Table)

LNM$SYSTEM_TABLE is the name of the system logical name table. The system table contains logical names that are available to all users of the system at the system level. Use the logical name LNM$SYSTEM to refer to it.

The following logical names are automatically defined in the system table when the system starts up:

• DBG$INPUT
  Default input stream for the OpenVMS Debugger, equated to SYS$INPUT at the process level.
• DBG$OUTPUT
  Default output stream for the OpenVMS Debugger, equated to SYS$OUTPUT at the process level.
• SYS$COMMON
  SYS$SYSDEVICE:[SYSn.SYSCOMMON.], where n is the root directory number of your processor. Device and directory name for the common part of SYS$SYSROOT.
• SYS$ERRORLOG
  Device and directory name of error log data files. By default, SYS$SYSROOT:[SYSERR].
• SYS$EXAMPLES
  Device and directory name of system examples. By default, SYS$SYSROOT:[SYSHLP.EXAMPLES].
• SYS$HELP
  Device and directory name of system help files. By default, SYS$SYSROOT:[SYSHLP].
• SYS$INSTRUCTION
  Device and directory name of system instruction data files. By default, SYS$SYSROOT:[SYSCBI].
• SYS$LIBRARY
  Device and directory name of system libraries. By default, SYS$SYSROOT:[SYSLIB].
• SYS$LOADABLE_IMAGES
  Device and directory of operating system executive loadable images, device drivers, and other executive-loaded code. By default, SYS$SYSROOT:[SYS$LDR].
• SYS$MAINTENANCE
  Device and directory name of system maintenance files. By default, SYS$SYSROOT:[SYSMAINT].
• SYS$MANAGER
  Device and directory name of system manager files. By default, SYS$SYSROOT:[SYSMGR].
• SYS$MESSAGE
  Device and directory name of system message files. By default, SYS$SYSROOT:[SYSMSG].
• SYS$NODE
  Network node name for the local system if DECnet for OpenVMS is active on the system and you are connected to a network.
• SYS$PROCDMP
  Directory (set by user) into which image dumps are to be written. No default setting.
• SYS$SHARE
  Device and directory name of system shareable images. By default, SYS$SYSROOT:[SYSLIB].
• SYS$SPECIFIC
  Device and directory name for node-specific part of SYS$SYSDEVICE. By default, SYS$SYSDEVICE:[SYSn.], where n is the root directory number of your processor.
• SYS$STARTUP
  Device and directory name of system startup files. By default, a search list that points first to SYS$SYSROOT:[SYS$STARTUP] and then to SYS$MANAGER.
• SYS$SYSDEVICE
  System disk containing system directories (usually SYS$DISK).
• SYS$SYSROOT
  Device and root directory for system directories. By default, a search list that points first to SYS$SYSDEVICE:[SYSn.], where n is the root directory number of your processor, and then points to SYS$COMMON.
• SYS$SYSTEM
  Device and directory of operating system programs and procedures. By default, SYS$SYSROOT:[SYSEXE].
• SYS$TEST
  Device and directory name of User Environment Test Package (UETP) files. By default, SYS$SYSROOT:[SYSTEST].
• SYS$UPDATE
  Device and directory name of system update files. By default, SYS$SYSROOT:[SYSUPD].

LNM$TEMPORARY_MAILBOX is a logical name that is defined as LNM$JOB. Logical names associated with temporary mailboxes are entered in the logical name table to which the logical name LNM$TEMPORARY_MAILBOX iteratively translates.

13.8 Displaying Logical Names

Use the SHOW LOGICAL command to display logical names and their equivalence strings.

Sometimes the definition of a logical name includes another logical name. The SHOW LOGICAL command performs iterative translations. It then displays both the equivalence string and the level of translation. Level numbers are zero based; that is, 0 is the first level, 1 is the second, and so on. To display only the first translation found for a specified logical name, use the SHOW TRANSLATION command. (For more information, see the OpenVMS DCL Dictionary.)

13.8.1 Examples

• In the following example, the logical name MYDISK, is displayed. Two translations are performed; the number 1 indicates the second level of translation:

  $ SHOW LOGICAL MYDISK
    "MYDISK" = "WORK4" (LNM$PROCESS_TABLE)
  1 "WORK4" = "$255$DUA17:" (LNM$SYSTEM_TABLE)
  

• In the following example, the equivalence string for the logical name WORKFILE is displayed:

  $ SHOW LOGICAL WORKFILE
  "WORKFILE" = "DISK2:[WALSH.REPORTS]WORK_SUMMARY.DAT" (LNM$PROCESS_TABLE)
  

  
  The logical name, its translation, and the table where the logical name is found are displayed.

If you use the SHOW LOGICAL command to determine the equivalence string for a process-permanent file (see Section 13.10), the command displays only the device portion of the string. For example:

$ SHOW LOGICAL SYS$INPUT
"SYS$INPUT" = "_TTB4:" (LNM$PROCESS_TABLE)

To display the access mode for a logical name, use the SHOW LOGICAL/FULL command, as follows:

$ SHOW LOGICAL/FULL PROJECT
  "PROJECT" [super] = "DISK1:[JONES]" (LNM$PROCESS_TABLE)

This example displays the logical name PROJECT in supervisor mode.

13.8.4 Displaying Logical Name Tables

By default, the SHOW LOGICAL command searches your process, job, group, and system tables. However, you can change the default search order or specify other logical name tables to be searched. To display the entries in a particular logical name table, use the /TABLE qualifier. You can also use the /GROUP, /SYSTEM, /JOB, and /PROCESS qualifiers to display the logical names in the group, system, job, and process logical name tables, respectively.

13.8.5 Example

In the following example, the command displays the logical names in the process logical name table (LNM$PROCESS):

$ SHOW LOGICAL/TABLE=LNM$PROCESS
(LNM$PROCESS_TABLE) 
  "DECW$DISPLAY" = "_WSA30:" 
  "SYS$COMMAND" = "_FIFI$VTA65:" 
  "SYS$DISK" [super] = "WORK1:" 
  "SYS$DISK" [exec] = "WORK1:" 
  "SYS$ERROR" = "_FIFI$VTA65:" 
  "SYS$INPUT" = "_FIFI$VTA65:" 
  "SYS$OUTPUT" [super] = "_FIFI$VTA65:" 
  "SYS$OUTPUT" [exec] = "_FIFI$VTA65:" 
  "TT" = "_VTA65:"

To display the relationship of directory tables to logical name tables, enter the SHOW LOGICAL/STRUCTURE command, as shown in the following example:

$ SHOW LOGICAL/STRUCTURE
(LNM$PROCESS_DIRECTORY) 
    (LNM$PROCESS_TABLE) 
(LNM$SYSTEM_DIRECTORY) 
    (LNM$GROUP_000360) 
    (LNM$JOB_806E98E0) 
    (LNM$SYSTEM_TABLE)

This example shows the process table, LNM$PROCESS_TABLE, in the process directory table, and the group, job, and system tables in the system directory table.

13.9 Deleting Logical Names and Logical Name Tables

To delete a logical name, use the DEASSIGN command. When you define logical names in your process and job logical name tables, they are not deleted until your process terminates or they are explicitly deleted by user actions. However, if you specify the /USER_MODE qualifier to the DEFINE command, the logical name is defined in the process logical name table and deleted automatically after executing the next command image.

To delete a logical name ending with a colon, specify two colons. The DEASSIGN command, like the ASSIGN command, removes one colon before it searches the logical name table for a match.

To delete a logical name table, specify the table that contains it (the system or process directory logical name table) and the name of the table. All logical names in descendant tables (and the descendant tables themselves) are deleted when you delete a parent logical name table.

To delete a shareable logical name table, you must have DELETE access to the table or SYSPRV privilege.

13.9.1 Examples

• In the following example, the command deletes the logical name WORKFILE:

  $ DEASSIGN WORKFILE
  

• In the following example, the logical name table TAX is deleted from the process directory table:

  $ DEASSIGN/TABLE=LNM$PROCESS_DIRECTORY TAX
  

Process-permanent logical names are created by DCL when you log in and they remain defined for the life of your process. You cannot deassign these logical names. You can redefine them (by specifying a different equivalence string in a DEFINE command) but if the redefined name is later deassigned, the process-permanent name is reestablished.

13.10.1 Available Process Permanent Logical Names

The following process-permanent logical names are available:

• SYS$INPUT
  Logical name that refers to the default input device or file
• SYS$OUTPUT
  Logical name that refers to the default output device or file
• SYS$ERROR
  Logical name that refers to the default device or file to which the system writes messages
• SYS$COMMAND
  Logical name that refers to the value of SYS$INPUT when you log in

When you use the system interactively, DCL equates SYS$INPUT, SYS$OUTPUT, SYS$ERROR, and SYS$COMMAND to your terminal. However, when you execute command procedures and submit batch jobs, DCL creates new equivalence strings for these logical names.

13.10.3 Executing Command Procedures Interactively

When you execute a command procedure interactively, the following occur:

• SYS$INPUT is equated to the command procedure. Therefore, DCL obtains data from the command procedure. This assignment is temporary. After the command procedure terminates, SYS$INPUT regains its original value.
• SYS$OUTPUT, SYS$COMMAND, and SYS$ERROR remain equated to the terminal.

When you submit a batch job, the following occur:

• SYS$INPUT and SYS$COMMAND are equated to the batch job command procedure.
• SYS$OUTPUT and SYS$ERROR are equated to the batch job log file.

When you nest command procedures (that is, when you write a command procedure that executes other command procedures), the equivalence string for SYS$INPUT changes to point to the command procedure that is currently executing. However, the equivalence strings for SYS$OUTPUT, SYS$ERROR, and SYS$COMMAND remain the same unless you explicitly change them.

13.10.6 Opening Files

In addition, when you enter a command that opens a file, DCL opens the file as a process-permanent file. For example, if you open a file with the OPEN command, this file is opened as a process-permanent file. The file remains open until you explicitly close the file or until you log out.

Process-permanent files are stored in a special area in memory. Note that if you keep a large number of files open at the same time, you can exhaust this area. If this occurs, close some of the files (or log out).

13.11 Using Process-Permanent Logical Names as File Specifications

This section describes how to use process-permanent logical names as file specifications. In command procedures, you can use these names to read data from the terminal and to display data (see Chapter 15 and Chapter 16).

13.11.1 Redefining SYS$INPUT

You can redefine SYS$INPUT so that a command procedure reads input from the terminal or another file.

Note that if you redefine SYS$INPUT, DCL ignores your definition. DCL always obtains input from the default input stream. However, images such as command procedures can use your definition for SYS$INPUT.

13.11.2 Examples

In the following example, the commands shown are included in a command procedure to enable editing a file from a command procedure:

$ DEFINE/USER_MODE SYS$INPUT SYS$COMMAND
$ EDIT/TPU MYFILE.DAT
   .
   .
   .

SYS$INPUT is redefined as SYS$COMMAND so that the editor obtains input from the terminal rather than from the command procedure file (the default). SYS$COMMAND refers to the terminal, the initial input stream when you logged in. The /USER_MODE qualifier tells the command procedure that SYS$INPUT is redefined only for the duration of the next image. In this example, the next image is the editor. When the editor is finished, SYS$INPUT resumes its default value. In this case, the default value is the command procedure file.

13.11.3 Redefining SYS$OUTPUT

You can redefine SYS$OUTPUT to redirect output from your default device to another file. When you redefine SYS$OUTPUT, the system opens a file with the name you specify in the logical name assignment. When you define SYS$OUTPUT, all subsequent output is directed to the new file.

Remember to deassign SYS$OUTPUT or output will continue to be written to the file you specify. Note that you can redefine SYS$OUTPUT in user mode (with DEFINE/USER_MODE) to redirect output from an image. This definition is in effect only until the next command image is executed. Once the command image is executed (that is, the output is captured in a file), the logical name SYS$OUTPUT resumes its default value.

When you log in, the system creates two logical names called SYS$OUTPUT. One name is created in executive mode; the other name is created in supervisor mode. You can supersede the supervisor mode logical name by redefining SYS$OUTPUT. If you deassign the supervisor mode name, the system redefines SYS$OUTPUT in supervisor mode, using the executive mode equivalence string. You cannot deassign the executive mode name.

When you redefine SYS$OUTPUT to a file, the logical name contains only the device portion of the file specification even though the output is directed to the file you specify.

If the system cannot open the file you specify when you redefine SYS$OUTPUT, an error message displays.

After you redefine SYS$OUTPUT, most commands direct output to the existing version of the file. However, certain commands create a new version of the file before they write output.

13.11.4 Examples

• In the following example, SYS$OUTPUT is defined as MYFILE.LIS before the SHOW DEVICES command is entered. The display produced by SHOW DEVICES is directed to MYFILE.LIS in the current directory rather than to the terminal. The data can be manipulated as would any other text file:

  $ DEFINE SYS$OUTPUT MYFILE.LIS
  $ SHOW DEVICES
  

• In the following example, SYS$OUTPUT is redefined to the file TEMP.DAT. When SYS$OUTPUT is redefined, output from DCL and from images is directed to the file TEMP.DAT. The output from the SHOW LOGICAL command and from the SHOW TIME command is also sent to TEMP.DAT. When SYS$OUTPUT is deassigned, the system closes the file TEMP.DAT and redefines SYS$OUTPUT to the terminal. When the TYPE command is entered, the output collected in TEMP.DAT displays on the terminal:

  $ DEFINE SYS$OUTPUT TEMP.DAT
  $ SHOW LOGICAL SYS$OUTPUT
  $ SHOW TIME
  $ DEASSIGN SYS$OUTPUT
  $ TYPE TEMP.DAT
     "SYS$OUTPUT" = "DISK1:" (LNM$PROCESS_TABLE) 
    06-MAY-1996 13:26:53
  

  
  When SYS$OUTPUT is redefined, the equivalence string contains the device name DISK1, not the full file specification.

You can redefine SYS$ERROR to direct error messages to a specified file. However, if you redefine SYS$ERROR so it is different from SYS$OUTPUT (or if you redefine SYS$OUTPUT without also redefining SYS$ERROR), DCL commands send informational, warning, error, and severe error messages to both SYS$ERROR and SYS$OUTPUT. Therefore, you receive these messages twice---once in the file indicated by the definition of SYS$ERROR and once in the file indicated by SYS$OUTPUT. Success messages are sent only to the file indicated by SYS$OUTPUT.

DCL commands and images, which use standard error display mechanisms, send error messages to both SYS$ERROR and SYS$OUTPUT even when SYS$ERROR is different from SYS$OUTPUT. However, if you redefine SYS$ERROR, then run an image that references SYS$ERROR, the image sends error messages only to the file indicated by SYS$ERROR. This is true even if SYS$ERROR is different from SYS$OUTPUT.

13.11.6 Redefining SYS$COMMAND

Although you can redefine SYS$COMMAND, DCL ignores your definition. DCL always uses the default definition for your initial input stream. However, if you execute an image that references SYS$COMMAND, the image can use your new definition.

13.12 Logical Name Translation

When the system reads a file specification or device name in a DCL command line, it examines the file specification or device name to see whether the leftmost component is a logical name. If the leftmost component ends with a colon, space, comma, or a line terminator (for example, Return), the system attempts to translate it as a logical name. If the leftmost component ends with any other character, the system does not attempt to translate it as a logical name.

13.12.1 Examples

• After you enter the command shown in this example, the system checks to see whether PUP is a logical name because PUP is the leftmost component of the file specification. Because the leftmost component is terminated with Return, the system attempts to translate PUP.

  $ TYPE PUP [Return]
  

• After you enter the command shown this example, the system checks whether DISK is a logical name. The system attempts to translate DISK because it is the leftmost component and ends with a colon. The system does not check PUP:

  $ TYPE DISK:PUP [Return]
  

• In the following example, the system does not try to translate [DRYSDALE]PUP because the leftmost component ends with a right square bracket (]):

  $ TYPE [DRYSDALE]PUP [Return]
  

By default, when the system translates logical names in file specifications, it searches the process, job, group, and system tables in that order and uses the first match it finds.

  6489P022.HTM
  OSSG Documentation
  22-NOV-1996 13:17:08.87

Copyright © Digital Equipment Corporation 1996. All Rights Reserved.

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