Tru64 UNIX
Ladebug Debugger Manual

(ladebug) alias x "set $lang=\"C++\" " (ladebug) alias x x set $lang="C++" (ladebug)

(ladebug) alias ada "ignore sigalrm; ignore sigfpe; set $lang=\"Ada\";" (ladebug) alias ada ada ignore sigalrm; ignore sigfpe; set $lang="Ada"; (ladebug)

Note that in the first example there is a space between the last two quotation marks. In the second example there is a semicolon. The two quotation marks cannot be together; they must be separated by a space or character(s).
Invoke the alias by entering the alias name, including an argument if the alias definition specified an argument.
Use the unalias command to delete an alias.
Alias commands cannot contain more than 56 arguments.
The following predefined aliases are included with the debugger:

S next Si nexti W list $curline - 10:20 a assign att attach b stop at bp stop in c cont d delete det detach e file f func g goto h history j status l list li ($curpc)/10i; set $curpc = $curpc + 40 n next ni nexti p print pd printf "%d", pi playback input plist show process all po printf "0%o", pr printregs ps printf "%s", px printf "0x%lx", q quit r rerun ri record input ro record output s step si stepi sw switch switch process t where tlist show thread all (show thread when the kernel debugging option is used) ts where thread all tset thread (only defined during kernel debugging) tstack where thread all u list $curline - 9:10 w list $curline - 5:10 wi ($curpc - 20)/10i wm watch memory wv watch variable

assign target = expression

• Use the assign command to change the value of a variable, memory address, or expression that is accessible according to the scope and visibility rules of the language. The expression can be any expression that is valid in the current context.
  For C++:

  assign [classname::]member = ["filename"] `expression assign [object.]member = ["filename"] `expression

  
  For C++, use the assign command to modify static and object data members in a class, and variables declared as reference types, type const, or type static. The address referred to by a reference type cannot be changed, but the value at that address can be changed.

• Use the attach command to connect to a running process. Supply the process ID number and image file name.

• Use the call command to execute a single function. Specify the function as if you were calling it from within the program. If the function has no parameters, specify empty parentheses.
  You can nest called functions by setting a breakpoint in a function and executing it using the call command. When execution suspends at the breakpoint, use this command to execute the nested function.
  For multithreaded applications, the call is made in the context of the current thread.
  For C++: When you set the $overloadmenu debugger variable to 1 and call an overloaded function, the debugger lists the overloaded functions and calls the function you specify.

• Enter the catch command or the ignore command without an argument to see which operating system signals the debugger currently traps or ignores. Use the catch command or the ignore command followed by an argument to trap or ignore, respectively, that signal.
  Only one signal at a time can be added to, or removed from, the list of trapped or ignored signals.
  The catch and ignore commands operate on a per-program basis; you must first load a program (using the load command) or attach to a process (using the attach command).

• Enter the catch unaligned command to instruct the debugger to stop when unaligned data access occurs in the debuggee process. The debugger stops at the instruction following the instruction where the unaligned access occurs, and issues a message. The default is ignore unaligned.

• For C++: Use the class command without an argument to display the current class scope. Specify an argument to change the class scope. After the class scope is set, refer to members of the class by omitting the classname:: prefix.
  Constructors and destructors of nested classes must be accessed with the class command. Use the second syntax form for a constructor, and the third syntax form for a destructor.
  Setting the class scope nullifies the function scope.

• Use the cont command without a parameter value to resume program execution until a breakpoint, a signal, an error, or the end of the program is encountered. Specify a signal parameter value to send an operating system signal to the program continuing execution. Specify the linenumber argument to halt program execution when that line number is reached. Specify the in function argument to halt the program when the named function is reached.
• When you use the cont command, Ladebug resumes execution of the entire process.
  The signal parameter value can be either a signal number or a string name (for example, SIGSEGV). The default is 0, which allows the program to continue execution without specifying a signal. If you specify a signal parameter value, the program continues execution with that signal.
  The linenumber parameter value is used to resume execution and then halt when the specified source line is reached.
  The form of the optional linenumber argument must be either:
  • linenumber, a positive numeric, which indicates the line number of the current source file where execution is to be halted
  • "filename":linenumber, which explicitly identifies both the source file and the line number where execution is to be halted
  
  The function argument is used to continue until the named function is reached. If the function name is overloaded and the user does not resolve the scope of the function in the command line, the debugger prompts the user with the list of overloaded functions bearing that name from which to choose.
  The form of the option function argument must be a valid function name.

• Enter the delete command followed by the number or numbers associated with a breakpoint, trace, or watch (as listed by the status command) to remove the specified breakpoint, tracepoint or watchpoint.
  Enter the delete all command or the delete * command to remove all breakpoints, tracepoints, or watchpoints.
  This command operates on a per-program basis; you must first load a program (using the load command) or attach to a process (using the attach command).

• Use the delsharedobj command to remove the symbol table information for the specified shared object from the debugger.

• Use the detach command with process IDs to detach from the specified running process or processes. Use the show process all or show process * command to display a list of processes running under debugger control. If you do not specify a process ID, Ladebug detaches from the current process. Detaching from a process disables your ability to debug that process.

• Enter the disable command followed by the number or numbers associated with a breakpoint, trace, or watch (as listed by the status command) to disable all breakpoints, tracepoints, or watchpoints. Enter the disable all command or the disable * command to disable all breakpoints, tracepoints, and watchpoints.
  The disabled breakpoint is displayed in response to the status command but it is ignored during execution. Disabled breakpoints remain disabled until they are explicitly reactivated or deleted.
  This command operates on a per-program basis; you must first load a program (using the load command) or attach to a process (using the attach command).

• Use the up command or the down command without an argument to change the function scope to the function located one level up or down the stack. Enter a number argument to change the function scope to the function up or down the specified number of levels. If the number of levels exceeds the number of active functions on the stack, the function scope moves up or down as many levels as possible and the debugger issues a warning message.
  When the function scope changes, the debugger displays the source line corresponding to the last point of execution in that function.

• Use the dump command without an argument to list the parameters and local variables in the current function. To list the parameters and local variables in an active function, specify it as an argument.
  Enter the dump. command (include the dot) to list the parameters and local variables for all functions active on the stack.

• Enter the enable command followed by the number or numbers associated with a breakpoint, trace, or watch (as listed by the status command) to enable a breakpoint, tracepoint, or watchpoint.
  Enter the enable all command or the enable * command to activate all previously disabled breakpoints, tracepoints, and watchpoints.
  This command operates on a per-program basis; you must first load a program (using the load command) or attach to a process (using the attach command).

• Sets the value of the specified environment variable. If no variable is specified, the command displays the values of all environment variables. If a variable is specified but no value is specified, the variable is set to NULL.
  This command is not for the current debuggee's environment, but for the environment of any debuggees subsequently created with run or rerun commands.
  Note that export and setenv are synonyms.
  See Chapter 3 for more information on commands that manipulate the environment of subsequent debuggees.

• Enter the file command without an argument to display the name of the current file scope. Include the filename argument to change the file scope. Change the file scope to set a breakpoint in a function not in the file currently being executed. To see source code for a function not in the file currently being executed, use the file command to set the file scope and the use command to direct the search for the sources of that file.

• Use the func command without an argument to display the current function scope. To change the function scope to a function currently active on the stack, specify either the name of the function or the number corresponding to the stack activation level. (Enter the where command to display the stack trace.)
  When the function scope is changed, the debugger displays the source line corresponding to the last point of execution in that function.

• Use the goto command to branch to a line located in the function where execution is suspended. When you branch to a line, the source code between the line where execution suspended and the specified line is not executed.

• Enter the help command without an argument to display a list of debugger help topics. Include a command argument to display a description of that command. Include the ladebug argument to display a task-oriented list of commands.

• Enter the history command without an argument to display previously executed commands. The debugger displays the number of command lines defined for the $historylines debugger variable. (The default is 20 lines of user input.) Include an integer argument to display that number of previous commands.

• Enter the catch command or the ignore command without an argument to see which operating system signals the debugger currently traps or ignores. Use the catch command or the ignore command followed by an argument to trap or ignore, respectively, that signal.
  Only one signal at a time can be added to, or removed from, the list of trapped or ignored signals.
  The catch and ignore commands operate on a per-program basis; you must first load a program (using the load command) or attach to a process (using the attach command).

• Enter the ignore unaligned command, which is the default, to instruct the debugger not to stop when unaligned access occurs. (See also the catch unaligned command.)

• Use the kill command to terminate the program process leaving the debugger running. When a process terminates, breakpoints and traces previously set are retained. You can later rerun the program.

• Use the kps command to list all system processes. (This command is valid for local kernel debugging only.)

• The list command displays source-code lines beginning with the source line corresponding to the position of the program counter, the last line listed if multiple list commands are entered, or the line number specified as the first argument to the list command. Specify the exact range of source-code lines by including either the endline or the number of lines you want to display. The arguments can be expressions that evaluate to integer values.
  To display the source code for a particular function, enter the function as an argument.

• Use the listobj command to list all loaded objects, including the main image and the shared libraries. For each object, the information listed consists of the full object name (with pathname), the starting address for the text, the size of the text region, and whether the symbol table information has been read by the debugger.

• The load command loads an image file and optionally a core file. After loading an image file, enter the run command to start program execution.
  The unload command removes all related symbol table information that the debugger associated with the process being debugged, specified by either a process ID or image file.

• Use the next and the step commands to execute a line of source code. When the next line to be executed contains a function call, the next command executes the function being called and returns to the line immediately after the function call. The step command steps into the function and executes only the first line of the function.
  For multithreaded applications, use these commands to step the current thread while putting all other threads on hold.
  If the optional expression argument is supplied, Ladebug evaluates the expression as a positive integer that specifies the number of times to execute the command. The expression can be any expression that is valid in the current context.

• Use the stepi command and the nexti command to execute a machine instruction. When the instruction contains a function call, the stepi command steps into the function being called, and the nexti command executes the function being called.
  For multithreaded applications, use these commands to step the current thread while putting all other threads on hold.
  If the optional expression argument is supplied, Ladebug evaluates the expression as a positive integer that specifies the number of times to execute the command. The expression can be any expression that is valid in the current context.

• Use the patch command to correct bad data or instructions in executable disk files. The text, initialized data, or read-only data areas can be patched. The bss segment, as well as stack and register locations, cannot be patched because they do not exist on disk files.
  Use this command exclusively when you need to change the ondisk binary. Use the assign command when you need only to modify debuggee memory.
  If the image is executing when you issue the patch command, the corresponding location in the debuggee address space is updated as well. (The debuggee is updated regardless of whether the patch to disk succeeded, as long as the source and destination expressions can be processed by the assign command.) If the user program is loaded but not yet started, the patch to disk is performed without the corresponding assign to memory.

• Use the source command or the playback input command to execute debugger commands contained within a file. (Note that you can also execute debugger commands when you invoke Ladebug by creating an initialization file named .dbxinit. By default, Ladebug searches for this file during startup, first in your home directory; if it is not there, Ladebug searches the current directory, and then the object directory of the executable image, if specified.) Format the commands as if they were entered at the debugger prompt.
  When a command file is executed, the value of the $pimode debugger variable determines whether the commands are echoed. If the $pimode variable is set to 1, commands are echoed; if $pimode is set to 0 (the default), commands are not echoed. The debugger output resulting from the commands is always echoed.

• The pop command removes one or more execution frames from the call stack, undoing the work already done by the removed execution frames. The optional argument is the number of execution frames to remove from the call stack. If you do not specify the argument, one frame is removed. If specified, the number must be a positive integer less than or equal to the number of frames currently on the call stack.
  See Chapter 3 for more information.

• The print command displays the current value of a variable or expression that is visible in the current context, as defined by the scope and visibility rules of the program language. The expression can be any expression that is valid in the current context.
  The print @linenumber command displays the address of the specified line number. For example, print @10 displays the address of line number 10.
  For C++:

  print *this print object print [object.]member print *( derived_class *) object

  
  Use the print command to display the value of an object, including inherited members and the value of data members in an object. Type casts can be used to interpret a base class object as a derived class object, or to interpret a derived class object as a base class object. To interpret a base class type object as the derived type, use the last form of the print command.
  Use the $usedynamictypes variable to control whether Ladebug displays static (value = 0) or dynamic (value = 1) information. The default is dynamic.

• Displays the value of the specified environment variable. If none is specified, the command displays the values of all the environment variables.
  This command is not for the current debuggee's environment, but for the environment of any debuggees subsequently created with run or rerun commands.
  See Chapter 3 for more information on commands that manipulate the environment of subsequent debuggees.

• Use the printf command to format and display a complex structure. The format argument is a string expression of characters and conversion specifications using the same format specifiers as the printf C function.

• Use the printregs command to display the contents of all machine registers for the current thread. Register values are displayed in decimal or hexadecimal, depending on the value of the $hexints variable. The list of registers displayed by the debugger is machine dependent.

• Specify a specific process using the process ID number or the name of the image. Ladebug sets the current process context to the process ID or the process that runs the binary image. If there is more than one process running the same binary image, Ladebug warns you and leaves the process context unchanged. The debugger variables $childprocess and $parentprocess can also be specified in place of the process ID. (Ladebug automatically sets these variables when an application forks a child process.)

• Use the quit command to end the debugging session and return to the operating system prompt.

• Use the readsharedobj command to read in the symbol table information for the specified shared object. This object must be a shared library or loadable kernel module. The command can be used only when a debuggee program is specified; that is, either Ladebug has been invoked with it, or the debuggee was loaded by the load command.

• Use the record input command to save all the debugger commands to a file. The commands in the file can be executed using the source command or the playback input command.
  The record output command saves all debugger output to a file. The output is simultaneously echoed to the screen. (The program output is not saved.)
  The record io command saves both input to and output from the debugger.
  To stop recording debugger input or output, enter:

  (ladebug) record {input,output,io} /dev/null

• Use the return command without an argument to continue execution of the current function until it returns to its caller. If you include a function name, execution continues until control is returned to the specified function. The function must be active on the call stack.

• Use the run and rerun commands to start program execution. Enter program flags, options, and input and output redirections as arguments. If the rerun command is specified without arguments, the arguments entered with the previous run command are used.
  If the last modification time and size of the binary file, or any of the shared objects used by the binary file have changed since the last run command was issued, Ladebug automatically rereads the symbol table information. If this happens, the old breakpoint settings may no longer be valid after the new symbol table information is read.

• To examine the definitions of all debugger variables, enter the set command without arguments. (Use the print command to display the definition of a single debugger variable.)
  To define a debugger variable, enter the set command followed by a variable name, an equal sign, and a definition. Enclose string definitions in quotes. The definition can be any expression allowed by the language of the program being debugged.
  Use the unset command to delete a variable.
  If you want to remove an environment variable, or all environment variables, use the unsetenv command, not the unset command.
  The debugger contains many predefined variables to describe the current state of the debugger, and to enable you to customize the debugger environment. You can delete and redefine the predefined debugger variables in the same way you define your own variables. If you delete a predefined debugger variable, the debugger uses the default value for that variable. The settings on the predefined variables apply to all debugging processes.
  The debugger has the following predefined variables:

  $ascii	With the default value of 1, enables the print command to print character-type data as ASCII characters, only when the bit value is that of a printable 7-bit subset ASCII character. (Other bit values are printed as octal numbers.) With a value of 0, all printable ISO Latin-1 characters are printed as characters.
  $beep	With the default value of 1, causes a beep to sound when a user attempts to perform an illegal action while editing the debugger command line (for example, moving the cursor past the end of the line, or "yanking"---pasting -- from an empty cut buffer).
  $childprocess	Can be specified in place of the process ID. (Ladebug automatically sets this variable when an application forks a child process.)
  $catchexecs	When set to 1, instructs the debugger to notify the user and stop the program when a program execs. The default is 0.
  $catchforks	When set to 1, instructs the debugger to notify the user when a program forks a child process. The child process stops and is brought under debugger control. (By default, the parent process is not stopped. See the $stopparentonfork description.) The default is 0.
  $curevent	Is set to the event number of the current event at the start of an event, allowing its use within the expression of an event.
  $curfile	Specifies the current source-code file.
  $curline	Specifies the current line in the source file.
  $curpc	Specifies the current point of program execution. This variable is used by the wi and li aliases.
  $cursrcline	Specifies the line number of the last line of source code listed, plus one.
  $curthread	Indicates the thread ID of the current thread within the current process. You can change to a different thread by setting $curthread.
  $decints	When set to 1, all integers printed by the debugger are displayed as decimal numbers. The default is 0.
  $editline	With the default of 1, enables the command-line editing features. The command-line editing features are described in Chapter 1. For backward compatibility, you can set this variable to 0.
  $eventecho	When set to 1, echoes events (such as breakpoints) with event numbers when executed. The default is 1.
  $hasmeta	For international users. When set to 1, causes any 8-bit character to be interpreted as the corresponding 7-bit character plus the Meta character (which is the ALT key whose MSB bit represents a Meta modifier). This could be used for binding editing functions to ALT plus key sequences. The default depends on several factors, including the locale and whether the terminal has Meta capability. In the United States, the default is usually 0.
  $hexints	When set to 1, all integers are displayed as hexadecimal numbers. The default is 0.
  $historylines	Specifies the number of previously input commands listed in response to the history command. The default is 20.
  $indent	When set to 1, specifies that structures will be printed with added indentation to render them more readable. The default value is 1.
  $lang	Specifies the programming language used in the program being debugged. For mixed-language programs, $lang is set to the language corresponding to the current frame. The variable is updated when the program execution stops.
  $listwindow	Specifies how many lines the list command displays. The default is 20.
  $main	Specifies the name of the function that the debugger enters first. The default is main() , but this can be set to any function. This variable is useful when debugging languages whose primary function is called something other than main() .
  $maxstrlen	Specifies the maximum number of characters to print when the value of a string is printed. The default is 128.
  $octints	When set to 1, the debugger prints all integers as octal numbers. The default is 0.
  $overloadmenu	When debugging C++ programs only, if this variable is set to 1, a menu of overloaded functions is displayed so you can select the desired function from the list of type signatures of the function. When set to 0, no menu is displayed and you must disambiguate overloaded functions by providing the full type signature. The default is 1.
  $page	Controls debugger output pagination. When set, the debugger generated terminal output will be paginated. Default value is 1 (ON) for command-line interface and 0 (OFF) for the GUI.
  $pagewindow	Determines the number of lines per page to be displayed when output pagination is turned on. Default value is 0 which means dynamically adjust the page size to the user's window size.
  $parentprocess	Can be specified in place of the process ID in commands that take a process ID as an argument. (Ladebug automatically sets this variable when an application forks a child process.)
  $pid	Indicates the process ID of the current process. Only for use in kernel debugging (either local or remote).
  $pimode	Specifies whether the playback input command echoes input. If set to 1, commands from the script file are echoed. If set to 0, commands are not echoed. The default is 0.
  $prompt	Specifies the debugger prompt. The default is (ladebug).
  $repeatmode	When set to 1, causes the debugger to repeat the previous command if you press the Return key at the (ladebug) prompt. The default is 1.
  $stackargs	When set to 1, causes the values of arguments to be included in the output of the where, up, down , and dump commands. When large or complex values are passed by value, the output can be voluminous. You can set $stackargs to 0 to suppress the output of argument values. The default is 1.
  $stepg0	When set to 0, the debugger steps over calls to routines that are compiled without symbol information. When set to 1, the debugger steps into these calls. The default is 0.
  $stoponattach	When set to 1, causes the debugger to stop a running process right after attaching to it. When set to 0, causes the debugger to allow the process to run to completion; in this case, to interrupt the process, enter Ctrl/C. The default is 0.
  $stopparentonfork	When set to 1, instructs the debugger to stop the parent process when a program forks a child process. (See also the $catchforks description.) The default is 0.
  $threadlevel	Enables Ladebug to determine whether you are working with DECthreads or native threads. The default is decthreads if the application is multithreaded and is using DECthreads. Otherwise, the default is native. You can switch from one mode to the other by setting $threadlevel. In kernel mode, $threadlevel is always native.
  $tid	Indicates the thread ID of the current thread within the current process. You can change to a different thread by setting $tid. Only for use in kernel debugging (either local or remote).
  $usedynamictypes	When set to 1, instructs the debugger to display dynamic type information. When set to 0, static type information is displayed. The default is 1. Output of the print , trace , tracei , and whatis commands is affected.
  $verbose	When set to 1, specifies whether debugger output should include all possible program information, including base pointers and virtual function pointers (for C++ programs only). The default is 0.

• Sets the value of the specified environment variable. If no variable is specified, the command displays the values of all environment variables. If a variable is specified but no value is specified, the variable is set to NULL.
  This command is not for the current debuggee's environment, but for the environment of any debuggees subsequently created with run or rerun commands.
  Note that export and setenv are synonyms.
  See Chapter 3 for more information on commands that manipulate the environment of subsequent debuggees.

• Use the sh command to execute a Bourne shell command. Do not enclose the shell command and its arguments in quotations. For example:

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