Updated: 11 December 1998

OpenVMS Debugger Manual

Identifies the Ctrl-key sequence currently defined to abort the execution of a debugger command or to interrupt program execution.

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

Format

SHOW ABORT_KEY

Description

By default, the Ctrl/C sequence, when entered within a debugging session, aborts the execution of a debugger command and interrupts program execution. The SET ABORT_KEY command enables you to assign the abort function to another Ctrl-key sequence. The SHOW ABORT_KEY command identifies the Ctrl-key sequence currently in effect for the abort function.

Related commands:

• Ctrl/C
• SET ABORT_KEY

Example

DBG> SHOW ABORT_KEY
Abort Command Key is CTRL_C
DBG> SET ABORT_KEY = CTRL_P
DBG> SHOW ABORT_KEY
Abort Command Key is CTRL_P
DBG>
      

In this example, the first SHOW ABORT_KEY command identifies the default abort command key sequence, Ctrl/C. The SET ABORT_KEY = CTRL_P command assigns the abort-command function to Ctrl/P, as confirmed by the second SHOW ABORT_KEY command.

Indicates whether delivery of asynchronous system traps (ASTs) is enabled or disabled.

Format

SHOW AST

Description

The SHOW AST command indicates whether delivery of ASTs is enabled or disabled. The command does not identify an AST whose delivery is pending. The delivery of ASTs is enabled by default and with the ENABLE AST command. The delivery of ASTs is disabled with the DISABLE AST command.

Related commands:

• (ENABLE,DISABLE) AST

Example

DBG> SHOW AST
ASTs are enabled
DBG> DISABLE AST
DBG> SHOW AST
ASTs are disabled
DBG>
      

The SHOW AST command indicates whether the delivery of ASTs is enabled.

Identifies the default file specification established with the last SET ATSIGN command. The debugger uses this file specification when processing the execute procedure (@) command.

Format

SHOW ATSIGN

Description

Related commands:

• @ (Execute Procedure)
• SET ATSIGN

Examples

DBG> SHOW ATSIGN
No indirect command file default in effect, using DEBUG.COM
DBG>
      

This example shows that if you did not use the SET ATSIGN command, the debugger assumes command procedures have the default file specification SYS$DISK:[]DEBUG.COM.

DBG> SET ATSIGN USER:[JONES.DEBUG].DBG
DBG> SHOW ATSIGN
Indirect command file default is USER:[JONES.DEBUG].DBG
DBG>
      

In this example, the SHOW ATSIGN command indicates the default file specification for command procedures, as previously established with the SET ATSIGN command.

Displays information about breakpoints.

Format

SHOW BREAK

Qualifiers

/PREDEFINED

Displays information about predefined breakpoints.

/USER

Displays information about user-defined breakpoints.

Description

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

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

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

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

Related commands:

• (ACTIVATE,CANCEL,DEACTIVATE,SET) BREAK

Examples

DBG> SHOW BREAK
breakpoint at SUB1\LOOP 
breakpoint at MAIN\MAIN+1F 
   do (EX SUB1\D ; EX/SYMBOLIC PSL; GO) 
breakpoint at routine SUB2\SUB2 
   /after: 2
DBG>
      

The SHOW BREAK command identifies all breakpoints that are currently set. This example indicates user-defined breakpoints that are triggered whenever execution reaches SUB1\LOOP, MAIN\MAIN, and SUB2\SUB2, respectively.

DBG> SHOW BREAK/PREDEFINED
predefined breakpoint on Ada event "DEPENDENTS_EXCEPTION" 
   for any value 
predefined breakpoint on Ada event "EXCEPTION_TERMINATED" 
   for any value
DBG>
      

This command identifies the predefined breakpoints that are currently set. The example shows two predefined breakpoints, which are associated with Ada tasking exception events. These breakpoints are set automatically by the debugger for all Ada programs and for any mixed language program that is linked with an Ada module.

Identifies the currently active routine calls.

Format

SHOW CALLS [integer]

Parameters

integer

A decimal integer that specifies the number of routine calls to be identified. If you omit the parameter, the debugger identifies all routine calls for which it has information.

Description

The SHOW CALLS command shows a traceback that lists the sequence of active routine calls that lead to the routine in which execution is currently suspended. Any recursive routine calls are shown in the display, so you can use the SHOW CALLS command to examine the chain of recursion.

SHOW CALLS displays one line of information for each call frame on the call stack, starting with the most recent call. The top line identifies the currently executing routine, the next line identifies its caller, the following line identifies the caller of the caller, and so on.

Even if your program contains no routine calls, the SHOW CALLS command displays an active call. The reason for this is that your program has a stack frame built for it when it is first activated. Thus, if the SHOW CALLS display shows no active calls, either your program has terminated or the call stack has been corrupted.

On VAX processors, the sequence of routine calls corresponds to the sequence of call frames on the call stack. Whenever a call is made to a routine as your program executes, the operating system creates a separate call frame on the call stack. Each call frame stores information about the calling routine, for example, the PC value that enables the SHOW CALLS command to symbolize module and routine information.

On Alpha processors, a routine invocation can result in a stack frame procedure (with a call frame on the stack), a register frame procedure (with a call frame stored in the register set), or a null frame procedure (without a call frame). SHOW CALLS provides one line of information on all three: stack frame procedures, register frame procedures, and null frame procedures. (See the Alpha example below.)

The following information is provided for each line of the SHOW CALLS display:

• The name of the enclosing module. An asterisk (*) to the left of a module name indicates that the module is set.
• The name of the calling routine, provided the module is set (the first line shows the currently executing routine).
• The line number where the call was made in that routine, provided the module is set (the first line shows the line number at which execution is suspended).
• The value of the PC in the calling routine at the time that control was transferred to the called routine. On VAX processors, the PC value is shown as a memory address relative to the nearest preceding symbol value (for example, a routine) and also as an absolute address. On Alpha processors, the PC is shown as a memory address relative to the first code address in the module and also as an absolute address.

On Alpha processors, the output of a SHOW CALLS command may include system call frames in addition to the user call frames associated with your program. System call frames appear in the following circumstances:

• When an exception occurs
• When an asynchronous system trap occurs
• When a watchpoint occurs in system space

The display of system call frames does not indicate a problem.

Related commands:

• SHOW SCOPE
• SHOW STACK

Examples

DBG> SHOW CALLS
module name   routine name   line      rel PC      abs PC
 SUB2         SUB2                    00000002    0000085A 
*SUB1         SUB1              5     00000014    00000854 
*MAIN         MAIN             10     0000002C    0000082C
DBG>
 
      

This command displays information about the sequence of currently active procedure calls on a VAX system.

DBG> SHOW CALLS
 module name   routine name     line          rel PC           abs PC 
*MAIN           FFFF             31      00000000000002B8 00000000000203C4 
-the above appears to be a null frame in the same scope as the frame below 
*MAIN           MAIN             13      00000000000000A8 00000000000200A8 
                                         0000000000000000 FFFFFFFF8255A1F8
 
 
 
      

This example is on an Alpha system. Note that sections of routine prologues and epilogues appear to the debugger to be null frames. The portion of the prologue before the change in the frame pointer (FP) and the portion of the epilogue after restoration of the FP each look like a null frame, and are reported accordingly.

Identifies the default (/ADDRESS, /COMMAND, /PROCESS_GROUP, or /VALUE) currently in effect for the DEFINE command.

Format

SHOW DEFINE

Description

The default qualifier for the DEFINE command is the one last established with the SET DEFINE command. If you did not enter a SET DEFINE command, the default qualifier is /ADDRESS.

To identify a symbol defined with the DEFINE command, use the SHOW SYMBOL/DEFINED command.

Related commands:

• DEFINE
• DEFINE/PROCESS_GROUP
• DELETE
• SET DEFINE
• SHOW SYMBOL/DEFINED

Example

DBG> SHOW DEFINE
Current setting is: DEFINE/ADDRESS
DBG>
      

This command indicates that the DEFINE command is set for definition by address.

Identifies one or more existing screen displays.

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

Format

SHOW DISPLAY [display-name[,...]]

Parameters

display-name

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

Qualifiers

/ALL

Lists all display definitions.

/SUFFIX[=process-identifier-type]

Applies to a multiprocess debugging configuration (when DBG$PROCESS has the value MULTIPROCESS). Appends a process-identifying suffix to a display name. Use this qualifier only directly after a display name. The suffix denotes the visible process at the time the command was issued.

The /SUFFIX qualifier is used primarily in command procedures when you specify display definitions or key definitions that are bound to display definitions.

Use any of the following process-identifier-type keywords:

PROCESS_NAME	The display-name suffix is the process name.
PROCESS_NUMBER	The display-name suffix is the process number (as shown in a SHOW PROCESS display).
PROCESS_PID	The display-name suffix is the process identifier (PID).

If you specify /SUFFIX without a process-identifier-type keyword, the process identifier type used for the display-name suffix is, by default, the same as that used for the prompt suffix (see the SET PROMPT/SUFFIX command).

Description

The SHOW DISPLAY command lists all displays according to their order in the display list. The most hidden display is listed first, and the display that is on top of the display pasteboard is listed last.

For each display, the SHOW DISPLAY command lists its name, maximum size, screen window, and display kind (including any debug command list). It also identifies whether the display is removed from the pasteboard or is dynamic (a dynamic display automatically adjusts its window dimensions if the screen size is changed with the SET TERMINAL command).

Related commands:

• DISPLAY
• EXTRACT/SCREEN_LAYOUT
• (CANCEL) DISPLAY
• (SET,CANCEL,SHOW) WINDOW
• SHOW SELECT

Example

DBG> SHOW DISPLAY
display SRC at H1, size = 64, dynamic 
    kind = SOURCE (EXAMINE/SOURCE .%SOURCE_SCOPE\%PC) 
display INST at H1, size = 64, removed, dynamic 
    kind = INSTRUCTION (EXAMINE/INSTRUCTION .0\%PC) 
display REG at RH1, size = 64, removed, dynamic, kind = REGISTER 
display OUT at S45, size = 100, dynamic, kind = OUTPUT 
display EXSUM at Q3, size = 64, dynamic, kind = DO (EXAMINE SUM) 
display PROMPT at S6, size = 64, dynamic, kind = PROGRAM
DBG>
      

The SHOW DISPLAY command lists all displays currently defined. In this example, they include the five predefined displays (SRC, INST, REG, OUT, and PROMPT), and the user-defined DO display EXSUM. Displays INST and REG are removed from the display pasteboard: the DISPLAY command must be used to display them on the screen.

Indicates the action taken by the EDIT command, as established by the SET EDITOR command.

Format

SHOW EDITOR

Description

Related commands:

• EDIT
• SET EDITOR

Examples

DBG> SHOW EDITOR
The editor is SPAWNed, with command line 
    "EDT/START_POSITION=(n,1)"
DBG>
      

In this example, the EDIT command spawns the EDT editor in a subprocess. The /START_POSITION qualifier appended to the command line indicates that the editing cursor is initially positioned at the beginning of the line that is centered in the debugger's current source display.

DBG> SET EDITOR/CALLABLE_TPU
DBG> SHOW EDITOR
The editor is CALLABLE_TPU, with command line "TPU"
DBG>
      

In this example, the SHOW EDITOR command indicates that the EDIT command invokes the callable version of the DEC Text Processing Utility (DECTPU). The editing cursor is initially positioned at the beginning of source line 1.

Identifies the current event facility and the associated event names.

Event facilities are available for programs that call Ada routines or that use DECthreads services. On VAX processors, event facilities are also available for programs that call SCAN routines.

Format

SHOW EVENT_FACILITY

Description

The current event facility (ADA, THREADS, or SCAN) defines the eventpoints that you can set with the SET BREAK/EVENT and SET TRACE/EVENT commands.

The SHOW EVENT_FACILITY command identifies the event names associated with the current event facility. These are the keywords that you can specify with the (SET,CANCEL) BREAK/EVENT and (SET,CANCEL) TRACE/EVENT commands.

Related commands:

• (SET,CANCEL) BREAK/EVENT
• SET EVENT_FACILITY
• (SET,CANCEL) TRACE/EVENT
• SHOW BREAK
• SHOW TASK
• SHOW TRACE

Example

DBG> SHOW EVENT_FACILITY
event facility is THREADS
    ...
      

This command identifies the current event facility to be THREADS (DECthreads) and lists the associated event names that can be used with SET BREAK/EVENT or SET TRACE/EVENT commands.

Identifies the exit handlers that have been declared in your program.

Format

SHOW EXIT_HANDLERS

Description

The exit handler routines are displayed in the order that they are called (that is, last in, first out). The routine name is displayed symbolically, if possible. Otherwise, its address is displayed. The debugger's exit handlers are not displayed.

Example

DBG> SHOW EXIT_HANDLERS
exit handler at STACKS\CLEANUP
DBG>
      

This command identifies the exit handler routine CLEANUP, which is declared in module STACKS.

Displays information about one or more images that are part of your running program.

Format

SHOW IMAGE [image-name]

Parameters

image-name

Specifies the name of an image to be included in the display. If you do not specify a name, or if you specify the asterisk (*) wildcard character by itself, all images are listed. You can use the wildcard within an image name.

Description

The SHOW IMAGE command displays the following information:

• Name of the image
• Start and end addresses of the image
• Whether the image has been set with the SET IMAGE command (loaded into the run-time symbol table, RST)
• Current image that is your debugging context (marked with an asterisk (*))
• Total number of images selected in the display
• Number of bytes allocated for the RST and other internal structures

SHOW IMAGE does not display all of the memory ranges of an image installed using the /RESIDENT qualifier. Instead, this command displays only the process data region.

Related commands:

• (SET,CANCEL) IMAGE
• (SET,SHOW,CANCEL) MODULE

Example

DBG> SHOW IMAGE SHARE*
 image name            set    base address    end address 
 
*SHARE                 yes    00000200        00000FFF 
 SHARE1                no     00001000        000017FF 
 SHARE2                yes    00018C00        000191FF 
 SHARE3                no     00019200        000195FF 
 SHARE4                no     00019600        0001B7FF 
 
 total images: 5       bytes allocated: 33032
DBG>
      

This SHOW IMAGE command identifies all of the images whose names start with SHARE and which are associated with the program. Images SHARE and SHARE2 are set. The asterisk (*) identifies SHARE as the current image.

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