Creates a new screen display or modifies an existing display.
NOTE
This command is not available in the HP DECwindows Motif for
OpenVMS user interface to the debugger.
Format
DISPLAY display-name [AT window-spec] [display-kind] [, . . . ]
1 – Parameters
display-name
Specifies the display to be created or modified.
If you are creating a new display, specify a name that is not
already used as a display name.
If you are modifying an existing display, you can specify any of
the following entities:
o A predefined display:
SRC
OUT
PROMPT
INST
REG
FREG (Alpha and Integrity servers only)
IREG
o A display previously created with the DISPLAY command
o A display built-in symbol:
%CURDISP
%CURSCROLL
%NEXTDISP
%NEXTINST
%NEXTOUTPUT
%NEXTSCROLL
%NEXTSOURCE
You must specify a display unless you use /GENERATE (parameter
optional), or /REFRESH (parameter not allowed).
You can specify more than one display, each with an optional
window specification and display kind.
window-spec
Specifies the screen window at which the display is to be
positioned. You can specify any of the following entities:
o A predefined window. For example, RH1 (right top half).
o A window definition previously established with the SET WINDOW
command.
o A window specification of the form (start-line, line-count[,
start-column, column-count]). The specification can include
expressions which can be based on the built-in symbols %PAGE
and %WIDTH (for example, %WIDTH/4).
If you omit the window specification, the screen position depends
on whether you are specifying an existing display or a new
display:
o If you are specifying an existing display, the position of the
display is not changed.
o If you are specifying a new display, it is positioned at
window H1 or H2, alternating between H1 and H2 each time you
create another display.
display-kind
Specifies the display kind. Valid keywords are as follows:
DO Specifies an automatically updated output
(command[; . . . ]) display. The commands are executed in the
order listed each time the debugger gains
control. Their output forms the contents of
the display. If you specify more than one
command, the commands must be separated by
semicolons.
INSTRUCTION Specifies an instruction display. If selected
as the current instruction display with the
SELECT/INSTRUCTION command, it displays the
output from subsequent EXAMINE/INSTRUCTION
commands.
OUTPUT Specifies an output display. If selected
as the current output display with the
SELECT/OUTPUT command, it displays any
debugger output that is not directed to
another display. If selected as the current
input display with the SELECT/INPUT command,
it echoes debugger input. If selected as the
current error display with the SELECT/ERROR
command, it displays debugger diagnostic
messages.
REGISTER Specifies an automatically updated register
display. The display is updated each time the
debugger gains control.
SOURCE Specifies a source display. If selected
as the current source display with the
SELECT/SOURCE command, it displays the
output from subsequent TYPE or EXAMINE/SOURCE
commands.
SOURCE (command) Specifies an automatically updated source
display. The command specified must be a
TYPE or EXAMINE/SOURCE command. The source
display is updated each time the debugger
gains control.
You cannot change the display kind of the PROMPT display.
If you omit the display-kind parameter, the display kind depends
on whether you are specifying an existing display or a new
display:
o If you specify an existing display, the display kind is not
changed.
o If you specify a new display, an OUTPUT display is created.
2 – Qualifiers
2.1 /CLEAR
Erases the entire contents of a specified display. Do not use
this qualifier with /GENERATE or when creating a new display.
2.2 /DYNAMIC
/DYNAMIC (default)
/NODYNAMIC
Controls whether a display automatically adjusts its window
dimensions proportionally when the screen height or width is
changed by a SET TERMINAL command. By default (/DYNAMIC), all
user-defined and predefined displays adjust their dimensions
automatically.
2.3 /GENERATE
Regenerates the contents of a specified display. Only
automatically generated displays are regenerated. These include
DO displays, register displays, source (cmd-list) displays, and
instruction (cmd-list) displays. The debugger automatically
regenerates all these kinds of displays before each prompt. If
you do not specify a display, it regenerates the contents of all
automatically generated displays. Do not use this qualifier with
/CLEAR or when creating a new display.
2.4 /HIDE
Places a specified display at the bottom of the display
pasteboard (same as /PUSH). This hides the specified display
behind any other displays that share the same region of the
screen. You cannot hide the PROMPT display.
2.5 /MARK_CHANGE
/MARK_CHANGE
/NOMARK_CHANGE (default)
Controls whether the lines that change in a DO display each time
it is automatically updated are marked. Not applicable to other
kinds of displays.
When you use /MARK_CHANGE, any lines in which some contents
have changed since the last time the display was updated are
highlighted in reverse video. This qualifier is particularly
useful when you want any variables in an automatically updated
display to be highlighted when they change.
The /NOMARK_CHANGE qualifier (default) specifies that any lines
that change in DO displays are not to be marked. This qualifier
cancels the effect of a previous /MARK_CHANGE on the specified
display.
2.6 /POP
/POP (default)
/NOPOP
Controls whether a specified display is placed at the top of the
display pasteboard, ahead of any other displays but behind the
PROMPT display. By default (/POP), the display is placed at the
top of the pasteboard and hides any other displays that share the
same region of the screen, except the PROMPT display.
The /NOPOP qualifier preserves the order of all displays on the
pasteboard (same as /NOPUSH).
2.7 /PROCESS
/PROCESS[=(process-spec)]
/NOPROCESS (default)
Used only when debugging multiprocess programs (kept debugger
only). Controls whether the specified display is process specific
(that is, whether the specified display is associated only with a
particular process). The contents of a process-specific display
are generated and modified in the context of that process. You
can make any display process specific, except the PROMPT display.
The /PROCESS=(process-spec) qualifier causes the specified
display to be associated with the specified process. You must
include the parentheses. Use any of the following process-spec
forms:
[%PROCESS_NAME] proc- The process name, if that name contains
name no space or lowercase characters. The
process name can include the asterisk
(*) wildcard character.
[%PROCESS_NAME] "proc- The process name, if that name contains
name" space or lowercase characters. You can
also use apostrophes (') instead of
quotation marks (").
%PROCESS_PID proc-id The process identifier (PID, a
hexadecimal number).
%PROCESS_NUMBER proc- The number assigned to a process when
number it comes under debugger control.
(or %PROC proc-number) Process numbers appear in a SHOW
PROCESS display.
proc-group-name A symbol defined with the
DEFINE/PROCESS_GROUP command to
represent a group of processes. Do not
specify a recursive symbol definition.
%NEXT_PROCESS The process after the visible process
in the debugger's circular process
list.
%PREVIOUS_PROCESS The process previous to the visible
process in the debugger's circular
process list.
%VISIBLE_PROCESS The process whose call stack, register
set, and images are the current context
for looking up symbols, register
values, routine calls, breakpoints,
and so on.
The /PROCESS qualifier causes the specified display to be
associated with the process that was the visible process when
the DISPLAY/PROCESS command was executed.
The /NOPROCESS qualifier (which is the default) causes the
specified display to be associated with the visible process,
which might change during program execution.
If you do not specify /PROCESS, the current process-specific
behavior (if any) of the specified display remains unchanged.
2.8 /PUSH
/PUSH
/NOPUSH
The /PUSH qualifier has the same effect as /HIDE. The /NOPUSH
qualifier preserves the order of all displays on the pasteboard
(same as /NOPOP).
2.9 /REFRESH
Refreshes the terminal screen. Do not specify any command
parameters with this qualifier. You can also use Ctrl/W to
refresh the screen.
2.10 /REMOVE
Marks the display as being removed from the display pasteboard,
so it is not shown on the screen unless you explicitly request
it with another DISPLAY command. Although a removed display is
not visible on the screen, it still exists and its contents are
preserved. You cannot remove the PROMPT display.
2.11 /SIZE
/SIZE:n
Sets the maximum size of a display to n lines. If more than n
lines are written to the display, the oldest lines are lost as
the new lines are added. If you omit this qualifier, the maximum
size of the display is as follows:
o If you specify an existing display, the maximum size is
unchanged.
o If you are creating a display, the default size is 64 lines.
For an output or DO display, /SIZE:n specifies that the display
should hold the n most recent lines of output. For a source or
instruction display, n gives the number of source lines or lines
of instructions that can be placed in the memory buffer at any
one time. However, you can scroll a source display over the
entire source code of the module whose code is displayed (source
lines are paged into the buffer as needed). Similarly, you can
scroll an instruction display over all of the instructions of
the routine whose instructions are displayed (instructions are
decoded from the image as needed).
3 – Description
You can use the DISPLAY command to create a display or to modify
an existing display.
To create a display, specify a name that is not already used as
a display name (the SHOW DISPLAY command identifies all existing
displays).
By default, the DISPLAY command places a specified display on
top of the display pasteboard, ahead of any other displays but
behind the PROMPT display, which cannot be hidden. The specified
display thus hides the portions of other displays (except the
PROMPT display) that share the same region of the screen.
For a list of the key definitions associated with the DISPLAY
command, type Help Keypad_Definitions_CI. Also, use the SHOW KEY
command to determine the current key definitions.
Related commands:
Ctrl/W
EXPAND
MOVE
SET PROMPT
(SET,SHOW) TERMINAL
(SET,SHOW,CANCEL) WINDOW
SELECT
(SHOW,CANCEL) DISPLAY
4 – Examples
1.DBG> DISPLAY REG
This command shows the predefined register display, REG, at its
current window location.
2.DBG> DISPLAY/PUSH INST
This command pushes display INST to the bottom of the display
pasteboard, behind all other displays.
3.DBG> DISPLAY NEWDISP AT RT2
DBG> SELECT/INPUT NEWDISP
In this example, the DISPLAY command shows the user-defined
display NEWDISP at the right middle third of the screen. The
SELECT/INPUT command selects NEWDISP as the current input
display. NEWDISP now echoes debugger input.
4.DBG> DISPLAY DISP2 AT RS45
DBG> SELECT/OUTPUT DISP2
In this example, the DISPLAY command creates a display named
DISP2 essentially at the right bottom half of the screen, above
the PROMPT display, which is located at S6. This is an output
display by default. The SELECT/OUTPUT command then selects
DISP2 as the current output display.
5.DBG> SET WINDOW TOP AT (1,8,45,30)
DBG> DISPLAY NEWINST AT TOP INSTRUCTION
DBG> SELECT/INST NEWINST
In this example, the SET WINDOW command creates a window named
TOP starting at line 1 and column 45, and extending down for
8 lines and to the right for 30 columns. The DISPLAY command
creates an instruction display named NEWINST to be displayed
through TOP. The SELECT/INST command selects NEWINST as the
current instruction display.
6.DBG> DISPLAY CALLS AT Q3 DO (SHOW CALLS)
This command creates a DO display named CALLS at window Q3.
Each time the debugger gains control from the program, the
SHOW CALLS command is executed and the output is displayed in
display CALLS, replacing any previous contents.
7.DBG> DISPLAY/MARK EXAM AT Q2 DO (EXAMINE A,B,C)
This command creates a DO display named EXAM at window Q2.
The display shows the current values of variables A, B, and C
whenever the debugger prompts for input. Any changed values are
highlighted.
8.all> DISPLAY/PROCESS OUT_X AT S4
This command makes display OUT_X specific to the visible
process (process 3) and puts the display at window S4.