pdx(1)pdx(1)Namepdx - pascal debugger
Syntaxpdx [-r] [objfile]
Description
The command is a tool for source level debugging and execution of Pas‐
cal programs. The objfile is an object file produced by the Pascal
translator If no objfile is specified, looks for a file named ``obj''
in the current directory. The object file contains a symbol table
which includes the name of the all the source files translated by to
create it. These files are available for perusal while using the
debugger.
If the file .pdxinit exists in the current directory, then the debugger
commands in it are executed.
The -r option causes the objfile to be executed immediately; if it ter‐
minates successfully exits. Otherwise it reports the reason for termi‐
nation and offers the user the option of entering the debugger or sim‐
ply letting continue with a traceback. If -r is not specified, just
prompts and waits for a command.
The commands are:
run [args] [< filename] [> filename]
Start executing objfile, passing args as command line arguments;
< or > can be used to redirect input or output in the usual man‐
ner.
trace [in procedure/function] [if condition]
trace source-line-number [if condition]
trace procedure/function [in procedure/function] [if condition]
trace expression at source-line-number [if condition]
trace variable [in procedure/function] [if condition]
Have tracing information printed when the program is executed.
A number is associated with the command that is used to turn the
tracing off (see the delete command).
The first argument describes what is to be traced. If it is a
source-line-number, then the line is printed immediately prior
to being executed. Source line numbers in a file other than the
current one must be preceded by the name of the file and a
colon, for example, ``mumble.p:17''.
If the argument is a procedure or function name then every time
it is called, information is printed telling what routine called
it, from what source line it was called, and what parameters
were passed to it. In addition, its return is noted, and if
it's a function then the value it is returning is also printed.
If the argument is an expression with an at clause then the
value of the expression is printed whenever the identified
source line is reached.
If the argument is a variable then the name and value of the
variable is printed whenever it changes. Execution is substan‐
tially slower during this form of tracing.
If no argument is specified then all source lines are printed
before they are executed. Execution is substantially slower
during this form of tracing.
The clause ``in procedure/function'' restricts tracing informa‐
tion to be printed only while executing inside the given proce‐
dure or function.
Condition is a Pascal boolean expression and is evaluated prior
to printing the tracing information; if it is false then the
information is not printed.
There is no restriction on the amount of information that can be
traced.
stop if condition
stop at source-line-number [if condition]
stop in procedure/function [if condition]
stop variable [if condition]
Stop execution when the given line is reached, procedure or
function called, variable changed, or condition true.
delete command-number
The trace or stop corresponding to the given number is removed.
The numbers associated with traces and stops are printed by the
status command.
status [> filename]
Print out the currently active trace and stop commands.
cont Continue execution from where it stopped. This can only be done
when the program was stopped by an interrupt or through use of
the stop command.
step Execute one source line.
next Execute up to the next source line. The difference between this
and step is that if the line contains a call to a procedure or
function the step command will stop at the beginning of that
block, while the next command will not.
print expression [, expression ...]
Print out the values of the Pascal expressions. Variables
declared in an outer block but having the same identifier as one
in the current block may be referenced as ``block-name . vari‐
able''.
whatis identifier
Print the declaration of the given identifier.
which identifier
Print the full qualification of the given identifier, that is
the outer blocks that the identifier is associated with.
assign variable expression
Assign the value of the expression to the variable.
call procedure(parameters)
Execute the object code associated with the named procedure or
function.
help Print out a synopsis of commands.
gripe Invokes a mail program to send a message to the person in charge
of
where Print out a list of the active procedures and functions and the
respective source line where they are called.
source filename
Read commands from the given filename. Especially useful when
the filename has been created by redirecting a status command
from an earlier debugging session.
dump [> filename]
Print the names and values of all active data.
list [source-line-number [, source-line-number]]
list procedure/function
List the lines in the current source file from the first line
number to the second inclusive. As in the editor ``$'' can be
used to refer to the last line. If no lines are specified, the
entire file is listed. If the name of a procedure or function
is given lines n-k to n+k are listed where n is the first state‐
ment in the procedure or function and k is small.
file [filename]
Change the current source file name to filename. If none is
specified then the current source file name is printed.
edit [filename]
edit procedure/function-name
Invoke an editor on filename or the current source file if none
is specified. If a procedure or function name is specified, the
editor is invoked on the file that contains it. Which editor is
invoked by default depends on the installation. The default can
be overridden by setting the environment variable EDITOR to the
name of the desired editor.
pi Recompile the program and read in the new symbol table informa‐
tion.
sh command-line
Pass the command line to the shell for execution. The SHELL
environment variable determines which shell is used.
alias new-command-name old-command-name
This command makes respond to new-command-name the way it used
to respond to old-command-name.
quit Exit
The following commands deal with the program at the px instruction
level rather than source level. They are not intended for general use.
tracei [address] [if cond]
tracei [variable] [at address] [if cond]
stopi [address] [if cond]
stopi [at] [address] [if cond]
Turn on tracing or set a stop using a px machine instruction
addresses.
xi address [, address]
Print the instructions starting at the first address. Instruc‐
tions up to the second address are printed.
xd address [, address]
Print in octal the specified data location(s).
Options-r Causes to be executed immediately. Normally prompts and waits for
a command.
Restrictions
The command does not understand sets, and provides no information about
files.
The command doesn't quite work for variant records.
Unexpected results occur if a procedure invoked with the call command
does a non-local goto.
Files
Pascal object file
initialization file
See Alsopi(1), px(1)
VAX pdx(1)
