Updated: 11 December 1998

OpenVMS Debugger Manual

This command shows that the variable COLOR is an enumeration type.

#5
DBG> SHOW SYMBOL/TYPE/ADDRESS *

This command displays all information about all symbols.

DBG> SHOW SYMBOL * IN MOD3\COUNTER
    routine MOD3\COUNTER 
    data MOD3\COUNTER\X 
    data MOD3\COUNTER\Y
DBG>
      

This command lists all the symbols that are defined in the scope denoted by the path name MOD3\COUNTER.

DBG> DEFINE/COMMAND SB=SET BREAK
DBG> SHOW SYMBOL/DEFINED SB
defined SB
    bound to: SET BREAK
    was defined /command
DBG>
      

In this example, the DEFINE/COMMAND command defines SB as a symbol for the SET BREAK command. The SHOW SYMBOL/DEFINED command displays that definition.

Displays information about the tasks of a multithread program (also called a tasking program).

Format

SHOW THREAD [task-spec[,...]]

Parameters

task-spec

Specifies a task value. Use any of the following forms:

• When the event facility is THREADS:
  • A task (thread) name as declared in the program, or a language expression that yields a task ID number.
  • A task ID number (for example, 2), as indicated in a SHOW THREAD display.
• When the event facility is ADA:
  • A task (thread) name as declared in the program, or a language expression that yields a task value. You can use a path name.
  • A task ID (for example, 2), as indicated in a SHOW THREAD display.
• One of the following task built-in symbols:

  %ACTIVE_TASK	The task that runs when a GO, STEP, CALL, or EXIT command executes.
  %CALLER_TASK	(Applies only to Ada programs.) When an accept statement executes, the task that called the entry associated with the accept statement.
  %NEXT_TASK	The task after the visible task in the debugger's task list. The ordering of tasks is arbitrary but consistent within a single run of a program.
  %PREVIOUS_TASK	The task previous to the visible task in the debugger's task list.
  %VISIBLE_TASK	The task whose call stack and register set are the current context for looking up symbols, register values, routine calls, breakpoints, and so on.

Do not use the asterisk (*) wildcard character. Instead, use the /ALL qualifier. Do not specify a task with /ALL, /STATISTICS, or /TIME_SLICE.

Qualifiers

/ALL

Selects all existing tasks for display---namely, tasks that have been created and (in the case of Ada tasks) whose master has not yet terminated.

/CALLS[=n]

Does a SHOW CALLS command for each task selected for display. This identifies the currently active routine calls (the call stack) for a task.

/FULL

When the event facility is THREADS, use the PTHREAD thread -f thread-number command.

Displays additional information for each task selected for display. The additional information is provided if you use /FULL by itself or with /CALLS or /STATISTICS.

/HOLD

/NOHOLD (default)

When the event facility is THREADS, use the PTHREAD tset -n thread-number command.

Selects either tasks that are on hold, or tasks that are not on hold for display.

If you do not specify a task, /HOLD selects all tasks that are on hold. If you specify a task list, /HOLD selects the tasks in the task list that are on hold.

If you do not specify a task, /NOHOLD selects all tasks that are not on hold. If you specify a task list, /NOHOLD selects the tasks in the task list that are not on hold.

/PRIORITY=(n[,...])

When the event facility is THREADS, use the PTHREAD tset -s thread-number command.

If you do not specify a task, selects all tasks having any of the specified priorities, n, where n is a decimal integer from 0 to 15. If you specify a task list, selects the tasks in the task list that have any of the priorities specified.

/STATE=(state[,...])

If you do not specify a task, selects all tasks that are in any of the specified states---RUNNING, READY, SUSPENDED, or TERMINATED. If you specify a task list, selects the tasks in the task list that are in any of the states specified.

/STATISTICS

(DEC Ada on VAX only) Displays task statistics for the entire tasking system. This information enables you to measure the performance of your tasking program. The larger the number of total schedulings (also known as context switches), the more tasking overhead there is.

/TIME_SLICE

(VAX only) Displays the current time-slice value, in seconds, as specified by a previous SET TASK/TIME_SLICE command. If no SET TASK/TIME_SLICE command was previously entered, displays the time-slice value, if any, that was specified in the program. If no time-slice value was previously established, the value is 0.0---that is, time slicing is disabled.

/TIME_SLICE is valid only when the event facility is ADA.

Description

Note SHOW TASK and SHOW THREAD are synonymous commands. They perform identically.

A task can first appear in a SHOW THREAD display as soon as it is created. A task can no longer appear in a SHOW THREAD display if it is terminated or (in the case of an Ada tasking program) if its master is terminated. By default, the SHOW THREAD command displays one line of information for each task selected.

Related commands:

• DEPOSIT/TASK
• EXAMINE/TASK
• (SET, SHOW) EVENT_FACILITY
• SET TASK|THREAD

Examples

DBG> SHOW EVENT_FACILITY
event facility is ADA
    ...
DBG> SHOW TASK/ALL
  task id   pri hold state   substate        task object 
* %TASK 1    7       RUN                   122624 
  %TASK 2    7  HOLD SUSP  Accept          H4.MONITOR 
  %TASK 3    6       READY Entry call      H4.CHECK_IN
DBG>
      

In this example, the SHOW EVENT_FACILITY command identifies ADA as the current event facility. The SHOW TASK/ALL command provides basic information about all the tasks that were created through Ada services and currently exist. One line is devoted to each task. The active task is marked with an asterisk (*). In this example, it is also the active task (the task that is in the RUN state).

DBG> SHOW TASK %ACTIVE_TASK,3,MONITOR
      

This command selects the active task, 3, and task MONITOR for display.

DBG> SHOW TASK/PRIORITY=6
      

This command selects all tasks with priority 6 for display.

DBG> SHOW TASK/STATE=(RUN,SUSP)
      

This command selects all tasks that are either running or suspended for display.

DBG> SHOW TASK/STATE=SUSP/NOHOLD
      

This command selects all tasks that are both suspended and not on hold for display.

DBG> SHOW TASK/STATE=(RUN,SUSP)/PRIO=7 %VISIBLE_TASK, 3
      

This command selects for display those tasks among the visible task and %TASK 3 that are in either the RUNNING or SUSPENDED state and have priority 7.

Identifies the current terminal screen height (page) and width being used to format output.

Note This command is not available in the DECwindows Motif interface to the debugger.

Format

SHOW TERMINAL

Description

The current terminal screen height and width are the height and width last established by the SET TERMINAL command. By default, if you did not enter a SET TERMINAL command, the current height and width are the height and width known to the terminal driver, as displayed by the DCL command SHOW TERMINAL (usually 24 lines and 80 columns for VT-series terminals).

Related commands:

• SET TERMINAL
• SHOW DISPLAY
• SHOW WINDOW

Example

DBG>  SHOW TERMINAL
terminal width: 80 
         page:  24 
         wrap:  80
DBG>
      

This command displays the current terminal screen width and height (page) as 80 columns and 24 lines, and the message wrap setting at column 80.

Displays information about tracepoints.

Format

SHOW TRACE

Qualifiers

/PREDEFINED

Displays information about predefined tracepoints.

/USER

Displays information about user-defined tracepoints.

Description

The SHOW TRACE command displays information about tracepoints that are currently set, including any options such as WHEN or DO clauses, /AFTER counts, and so on, and whether the tracepoints are deactivated.

By default, SHOW TRACE displays information about both user-defined and predefined tracepoints (if any). This is equivalent to entering the SHOW TRACE/USER/PREDEFINED command. User-defined tracepoints are set with the SET TRACE command. Predefined tracepoints are set automatically when you start the debugger, and they depend on the type of program you are debugging.

If you established a tracepoint using SET TRACE/AFTER:n, the SHOW TRACE command displays the current value of the decimal integer n, that is, the originally specified integer value minus 1 for each time the tracepoint location was reached. (The debugger decrements n each time the tracepoint location is reached until the value of n is 0, at which time the debugger takes trace action.)

On Alpha systems, the SHOW TRACE command does not display individual instructions when the trace is on a particular class of instruction (as with SET TRACE/CALL or SET TRACE/RETURN).

Related commands:

• (ACTIVATE, DEACTIVATE, SET, CANCEL) TRACE

Examples

DBG> SHOW TRACE
tracepoint at routine CALC\MULT 
tracepoint on calls: 
        RET     RSB     BSBB    JSB     BSBW    CALLG   CALLS
DBG>
      

In this VAX example, the SHOW TRACE command identifies all tracepoints that are currently set. This example indicates user-defined tracepoints that are triggered whenever execution reaches routine MULT in module CALC or one of the instructions RET, RSB, BSBB, JSB, BSBW, CALLG, or CALLS.

DBG_2> SHOW TRACE/PREDEFINED
predefined tracepoint on program activation 
 DO (SET DISP/DYN/REM/SIZE:64/PROC SRC_/SUF=PROCESS_NU AT H1 SOURCE 
        (EXAM/SOURCE .%SOURCE_SCOPE\%PC); 
    SET DISP/DYN/REM/SIZE:64/PROC INST_/SUF=PROCESS_NU AT H1 INST 
        (EXAM/INSTRUCTION .0\%PC)) 
predefined tracepoint on program termination
DBG_2>
      

This command identifies the predefined tracepoints that are currently set. The example shows the predefined tracepoints that are set automatically by the debugger for a multiprocess program (when DBG$PROCESS has the value MULTIPROCESS). The tracepoint on program activation triggers whenever a new process comes under debugger control. The DO clause creates a process-specific source display named SRC_n and a process-specific instruction display named INST_n whenever a process activation tracepoint is triggered. The tracepoint on program termination triggers whenever a process does an image exit.

Identifies the current type for program locations that do not have a compiler-generated type or, if you specify /OVERRIDE, the current override type.

Format

SHOW TYPE

Qualifiers

/OVERRIDE

Identifies the current override type.

Description

The current type for program locations that do not have a compiler-generated type is the type last established by the SET TYPE command. If you did not enter a SET TYPE command, the type for those locations is longword integer.

The current override type for all program locations is the override type last established by the SET TYPE/OVERRIDE command. If you did not enter a SET TYPE/OVERRIDE command, the override type is "none".

Related commands:

• CANCEL TYPE/OVERRIDE
• DEPOSIT
• EXAMINE
• (SET,SHOW,CANCEL) MODE
• (SET,SHOW,CANCEL) RADIX
• SET TYPE

Examples

DBG> SET TYPE QUADWORD
DBG> SHOW TYPE
type: quadword integer
DBG>
      

In this example, you set the type to quadword for locations that do not have a compiler-generated type. The SHOW TYPE command displays the current default type for those locations as quadword integer. This means that the debugger interprets and displays entities at those locations as quadword integers unless you specify otherwise (for example with a type qualifier on the EXAMINE command).

DBG> SHOW TYPE/OVERRIDE
type/override: none
DBG>
      

This command indicates that no override type has been defined.

Identifies the current vector mode (synchronized or nonsynchronized).

Applies to VAX vectorized programs.

Format

SHOW VECTOR_MODE

Description

The current vector mode is the mode established with the SET VECTOR_MODE command. If you did not enter a SET VECTOR_MODE command, the default vector mode is NONSYNCHRONIZED.

Related commands:

• SET VECTOR_MODE [NO]SYNCHRONIZED (VAX only)
• SYNCHRONIZE VECTOR_MODE (VAX only)

Example

DBG> SHOW VECTOR_MODE
Vector mode is nonsynchronized
DBG> SET VECTOR_MODE SYNCHRONIZED
DBG> SHOW VECTOR_MODE
Vector mode is synchronized
DBG>
      

The SHOW VECTOR_MODE command indicates the effect of the SET VECTOR_MODE command.

Displays information about watchpoints.

Format

SHOW WATCH

Description

The SHOW WATCH command displays information about watchpoints that are currently set, including any options such as WHEN or DO clauses, /AFTER counts, and so on, and whether the watchpoints are deactivated.

If you established a watchpoint using SET WATCH/AFTER:n, the SHOW WATCH command displays the current value of the decimal integer n, that is, the originally specified integer value minus 1 for each time the watchpoint location was reached. (The debugger decrements n each time the watchpoint location is reached until the value of n is 0, at which time the debugger takes watch action.)

Related commands:

• (ACTIVATE,CANCEL,DEACTIVATE,SET) WATCH

Example

DBG> SHOW WATCH
watchpoint of MAIN\X 
watchpoint of SUB2\TABLE+20
DBG>
      

This command displays two watchpoints: one at the variable X (defined in module MAIN), and the other at the location SUB2\TABLE+20 (20 bytes beyond the address denoted by the address expression TABLE).

Identifies the name and screen position of predefined and user-defined screen-mode windows.

Note This command is not available in the DECwindows Motif interface to the debugger.

Format

SHOW WINDOW [window-name[,...]]

Parameters

windowname

Specifies the name of a screen window definition. If you do not specify a name, or if you specify the asterisk (*) wildcard character by itself, all window definitions are listed. You can use the wildcard within a window name. Do not specify a window definition name with the /ALL qualifier.

Qualifiers

/ALL

Lists all window definitions.

Description

Related commands:

• (SHOW,CANCEL) DISPLAY
• (SET,SHOW) TERMINAL
• (SET,CANCEL) WINDOW
• SHOW SELECT

Example

DBG> SHOW WINDOW LH*,RH*
window LH1 at (1,11,1,40) 
window LH12 at (1,23,1,40) 
window LH2 at (13,11,1,40) 
window RH1 at (1,11,42,39) 
window RH12 at (1,23,42,39) 
window RH2 at (13,11,42,39)
DBG>
      

This command displays the name and screen position of all screen window definitions whose names start with LH or RH.

Creates a subprocess, enabling you to execute DCL commands without terminating a debugging session or losing your debugging context.

Note This command is not available in the DECwindows Motif interface to the debugger.

Format

SPAWN [DCL-command]

Parameters

DCL-command

Specifies a DCL command which is then executed in a subprocess. Control is returned to the debugging session when the DCL command terminates.

If you do not specify a DCL command, a subprocess is created and you can then enter DCL commands. Either logging out of the spawned process or attaching to the parent process (with the DCL command ATTACH) returns you to your debugging session.

If the DCL command contains a semicolon, you must enclose the command in quotation marks ("). Otherwise the semicolon is interpreted as a debugger command separator. To include a quotation mark in the string, enter two consecutive quotation marks ("").

Qualifiers

/INPUT=file-spec

Specifies an input DCL command procedure containing one or more DCL commands to be executed by the spawned subprocess. The default file type is .COM. If you specify a DCL command string with the SPAWN command and an input file with /INPUT, the command string is processed before the input file. After processing of the input file is complete, the subprocess is terminated. Do not use the asterisk (*) wildcard character in the file specification.

/OUTPUT=file-spec

Writes the output from the SPAWN operation to the specified file. The default file type is .LOG. Do not use the asterisk (*) wildcard character in the file specification.

/WAIT (default)

/NOWAIT

Controls whether the debugging session (the parent process) is suspended while the subprocess is running. The /WAIT qualifier (default) suspends the debugging session until the subprocess is terminated. You cannot enter debugger commands until control returns to the parent process.

The /NOWAIT qualifier executes the subprocess in parallel with the debugging session. You can enter debugger commands while the subprocess is running. If you use /NOWAIT, you should specify a DCL command with the SPAWN command; the DCL command is then executed in the subprocess. A message indicates when the spawned subprocess completes.

The kept debugger (that is, the debugger invoked with the DCL command DEBUG/KEEP) shares I/O channels with the parent process when it is run by a SPAWN/NOWAIT command. Therefore, in the DECwindows Motif interface, you must press the Return key twice on the DECterm from which the debugger was run after the debugger version number has appeared in the command view.

Optionally, you can execute the kept debugger in the following manner:

$ DEFINE DBG$INPUT NL: $ SPAWN/NOWAIT RUN DEBUG/KEEP

Description

The SPAWN command acts exactly like the DCL command SPAWN. You can edit files, compile programs, read mail, and so on without ending your debugging session or losing your current debugging context.

In addition, you can spawn a DCL command SPAWN. DCL processes the second SPAWN command, including any qualifier specified with that command.

Related command:

• ATTACH

Examples

DBG> SPAWN
$
      

This example shows that the SPAWN command, without a parameter, creates a subprocess at DCL level. You can now enter DCL commands. Log out to return to the debugger prompt.

DBG> SPAWN/NOWAIT/INPUT=READ_NOTES/OUTPUT=0428NOTES
      

This command creates a subprocess that is executed in parallel with the debugging session. This subprocess executes the DCL command procedure READ_NOTES.COM. The output from the spawned operation is written to the file 0428NOTES.LOG.

DBG> SPAWN/NOWAIT SPAWN/OUT=MYCOM.LOG @MYCOM
      

This command creates a subprocess that is executed in parallel with the debugging session. This subprocess creates another subprocess to execute the DCL command procedure MYCOM.COM. The output from that operation is written to the file MYCOM.LOG.

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