List of Examples

14-1	Sample Output for the find command	198
14-2	Sample Commands to Print NaT Registers	214

14 List of Examples

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HP gnu source-level debugger 5992-4701 manual List of Examples

Contents

Debugging with GDB Manual Page Table of Contents Breakpoints Continuing and stepping SignalsPrint settings Value history Stack frames Examining the Symbol Table Specifying a Debugging Target Batch Mode Stop when freeing unallocated or deallocated blocksScramble previous memory contents at malloc/free calls Commands for heap profiling Enhancements to the dumpcore command Support for the info target CommandSupport for the dumpcore command Example Illustrating Execution Path Recovery Debugging the application using GDB under Aries Command for evaluating the address of an expressionSupport for steplast command for C and C++ Detecting memory leaks using GDB under Aries HP-UX Terminal User Interface User-defined commands 287 18.2 Miscellaneous commands 265 16.3Setting Command History Feature in GDB 281 17.4 Command files 289 Commands for controlled output 290 20.9 Invalidation notices 303 20.7 Errors 302 20.822.2 How to report bugs 361 304 List of Tables List of Examples Contributors to GDB Summary of GDBFree Software Page Contributors to GDB Page Loading the Executable Let us use GDB to try to see what is going onSample GDB Session Here we describe how to set a breakpoint Setting Display widthSetting Breakpoints Running the executable under GDB Printing Variable Values Stepping into a subroutineExamining the Stack Setting Variable Values During a Session Listing Source Code Gdb c Continuing Definebaz,defnQUOTEfooUNQUOTE Baz Page Getting In and Out of GDB Invoking GDB Choosing files Files Processed. See Command files Choosing modes Time a stack frame is displayed which includes each GNU Emacs sets this option when it runs GDB as aLine number in a standard, recognizable fashion each Like two `\032 characters, followed by the file name Emacs Interface Quitting GDBRedirecting WDB input and output to a file Shell commands Page Command completion GDB CommandsCommand syntax GDB sounds bell press TAB again, to see Help , h Short list of named classes of commandsGetting help Complete Apropos reloadResults This is intended for use by GNU Emacs Getting help Page Starting your program Running Programs Under GDBCompiling for debugging Arguments, so that you may use normal Directory See Arguments To Your ProgramYour program. SeeProgram Environment Program. See Program Input and Output Arguments To Your ProgramProgram Environment Path environment variable For example, this commandDisplay the list of search paths for executables Do not supply varname, print the names Working directory Program Input and Output Debugging a Running Process Killing the child process Debugging programs with multiple threads New process 35 thread With the command argument threadno Here are commands to get more information about threadsThread apply command allows you to Display a summary of all threads currently Debugging programs with multiple processes Set the debugger response to a program call New process. The mode can beUnimpeded. This is the default Fork. The child process runs Stopping and Continuing Breakpoints Setting breakpoints See Break conditions page 59, for more Breakpoints Whether BreakpointCatchpoint Breakpoint is Marked to be When hitEnabled Breakpoints are Setting catchpoints Unloading of any dynamically loaded Call to vfork. This is currently onlyIs currently only available for HP-UX Shared library, or the unloading Selecting a frame page 73 . When Deleting breakpointsDisabling breakpoints Break conditions Stops your program only if the value Breakpoint, GDB prints an error messageNo symbol foo in current context Use condition, GDB checks expression Breakpoint command lists Breakpoint menus Cannot insert breakpoints Continuing and stepping Conditions Function Setting breakpoints page 52. This form of the command Signals Stops. See Automatic display Info handle is an alias for info signals Stopping and starting multi-thread programs Stopping and Continuing Examining the Stack Stack frames Backtraces Commands for Examining the StackStacks Without frames Selecting a frame With an argument, this command is used to select a stack Have existed longer. n defaults to oneWhen used without any argument, this command does not Information about a frame Setting catchpoints Page List Examining Source FilesPrinting source lines Show listsize Searching source files Specifying source directories Contains Source and machine codeShow directories Select the instruction set to use when Set disassembly-flavorDisassemble or x/i commands Disassembling the program viaPage Expressions Following forms of print command are supportedExamining Data To See Artificial arrays page 85, for more information Type addr Where it is defined. See Program variablesProgram variables Normally supposed to reside at addr You can print the contents of array with Artificial arrays Output formats Print, s null-terminated string, or Machine instruction. The default isExamining memory Time you use either x or print However, the count n must come first wx4 does not work See Output formats Automatic displayFor fmt specifying only a display format and not a size or For fmt i or s, or including a unit-size or a number Print settings Symbolic form of an address A symbol. This is the defaultFile name and line number of a symbol Address Setting number-of-elementsto zero Default is offStrings. When GDB starts, this limit is set to Short strings. The default is off Print using only seven-bit characters if this This is the default formatShow which format GDB is using to print Default Show whether C++ names in assembly listings These settings are of interest when debugging C++ programsDefault is on Would print Value history Convenience variables $exitcode Command, in which case it is a pointer to the type of $Format in which the data was printed Program being debugged terminates Or print the instruction to be executed next with RegistersInfo registers Info all-registers Info registers regname Or add four to the stack pointer3 with3with To get the bit pattern, try the following macro Printing Floating Point ValuesFloating point hardware This is what the macro produces 100 List of filename extensions and languages Using GDB with Different LanguagesSwitching between source languages Cpp Having GDB infer the source language Setting the working languageNot skip over function prologues when stepping Files An overview of type checking Displaying the languageType and range checking An overview of range checking Supported languages C++ Left shift, and right shift. Defined on integral types Expressions is 0 for false and non-zero for trueNon-zero for true Types and pointer types Expressions page 83. Same precedence as , above Class typesDouble colons also represent the GDB scope operator see C++ constants 1.3 C++ expressions GDB expression handling can interpret most C++ expressions C++ type and range checks C++ defaultsPrinting the variable or class returns Breakpoint menus GDB features for C++GDB and C See Breakpoint menus Fortran types supported FortranFortran types Greater than Less thanLess than or equal to Greater than or equal to Block Fortran special issuesCommonblockname Examining the Symbol Table Symbols will be read when needed Two commands give this outputAs with whatis, using ptype without an For example, for this variable declaration Do not replace symbol Allow GDB to reload the symbols forReplace symbol definitions Once. This is the default Tell GDB to resolve opaque types. An opaque SettingIs in another source file. The default is on Class, or union―for example, struct Altering Execution Assignment to variables Continuing at a different address Stores the value 4 into that memory location Returning from a function Giving your program a signalYou can use the following command to return from a function Return , return Calling program functionsPatching programs Is used as the return value from the function value Patching programs 124 Commands to specify files GDB Files See Optional warnings and messages Write the symbols for your program into a Option with any of the commands that loadGDB has the entire symbol table available Map in symbol information from this auxiliary Section If threshold is nonzero, symbols from all Symbols were loaded. Both the commands listTo display or set the threshold, use the commands New library has been loaded, until the symbol Specifying shared library locations Names where the desired shared libraries reside. GDBSearching the default system directories Megabytes Messages Errors reading symbol filesVerbose on. See Optional warnings GDB circumvents the error by ignoring this Symbol scope block as starting on the previousIs the symbol type of the uncomprehended Debug your program, though certain symbols Active targets Commands for managing targetsSpecifying a Debugging Target See Commands to specify files Choosing target byte order Executable Instruct GDB to assume the target is big-endianInstruct GDB to assume the target is little-endian Display GDBs current idea of the target byte order HP-UX Configuration-Specific Information Summary of HP Enhancements to GDB Implementation of ask mode for set follow-fork-mode Support for setting breakpoints using shared library name Command watchtarget Dependent Standard Library Routines for Run Time Checking HP-UX dependenciesLinker Dependencies Abort Unlink Atoi Getpid Close Srand Strchr Supported Platforms and Modes WDB Location HP-UX targetsSupport for Alternate root GDB location None Specifying object file directoriesLibrtc.sl location $WDBROOT/bin Opt/langtools/ n/a Bin $WDBROOT/bin Fix and continue debugging Fix and Continue compiler dependencies Fix and Continue restrictions Using Fix and Continue Run the program Example Fix and Continue sessionCompile the program Gdb edit Gdb b mainGdb run Make the necessary changes. In this case, add return total Gdb q Inline SupportInline Debugging in HP 9000 Systems Inline Debugging in Integrity Systems Breakpoint info frame disassemblyFollowing options available for the set inline-debugcommand Step next list backtrace frame n info locals info args Limitations Debugging Inline Functions in Integrity Systems Viewing and Evaluating Macro Definitions Info frame disassemblyDebugging Macros Debug=none Compiler Options to Enable Macro DebuggingEvaluating Macros Examples for Macro Debugging HP-UX Configuration-Specific Information Debugging Memory Problems Memory Debugging Methodologies When to suspect a memory leakMemory debugging restrictions Debugging Memory in Interactive Mode Heap growth. The default value is 100. Every Displays all current settings for memoryThis command are ignored from report. If Command discards the data existing in the file Debugging Memory Problems Specific pattern when it is allocated or Debugging when the string option is set forHave occurred and WDB reports the problem Such as attempting to access space that is freed Number of bytes, the debugger ignores it Use the info command to show list of memory leaksIf the user specifies a value less than 16 for User-specified value Gdb info leak Debugging Memory in Batch ModeSetting Configuration Options for Batch Mode Framecount=noframes or set heap-check frame-count noframes Sets the number of frames to be printed for leak context For 64 bit PA applications For 32 bit IPF applicationsFor 64 bit IPF applications For 64-bit IPF applications Environment variable setting for Batch mode debugging Ldpreload Log file for batch mode must be Aborts execution when heap objectsAborts execution when out of memory Stderr error message goes to stderr Example for Batch Mode RTC Complete one of the following steps Run the program as follows Rtcconfig file should contain entries such as the followingPreload the librtc library as follows For 32 bit PA applications Specifying the stack depth Configuring memory debugging settingsRun the program Start a debugging session as follows Specifying minimum leak size For example, if you use Stop when freeing unallocated or deallocated blocksScenarios in memory debugging Specifying minimum block size Syntax Scramble previous memory contents at malloc/free callsInteractive debugging mode set heap-check scramble on off Detect dangling pointers and dangling blocks Detect in-block corruption of freed blocks Memory Debugging Commands in Interactive and Batch Mode Off Heap Profiling Commands for heap profilingPoint you use the info heap command As the start of the heap, end of the heap, heap This example shows how to use this feature on HP-UX Set a breakpoint Commands to track the change in data segment value Changes for a given run Thread Debugging Support Support for Enabling and Disabling Specific Threads Backtrace Support for Thread Debugging Advanced Thread Debugging Support Enabling and Disabling Advanced Thread Debugging Features Pre-requisites for Advanced Thread Debugging Mixed-sched-policy onoff The set thread-check Onoff command checks if an applicationUnlock-not-own onoff The set thread-check unlock-not-own Cv-multiple-mxs onoff The set thread-check cv-multiple-mxs Command checks if any thread has terminated This returns an Einval error toUser and prints a warning message when this Different mutexes. The debugger transfers Exception or a cancel without joining or When this condition is detected. This situationCommand checks if a thread has terminated Created with the detach attribute. When an Condvar-id is provided, the command displays Provided, the command displays extendedIs provided, the command displays extended Rwlock-id is provided, the command displays For 64-bit PA applications Thread Debugging in Batch Mode For 64-bit PA applications, set Pre-requisites for Batch mode of Thread DebuggingFor 64 bit IPF applications, set And/Or Set the environment variable Batchrtc to on as Opt/langtools/lib/hpux64/librtc.so Limitations in Batch mode of thread debugging Thread Debugging in +check ModeWhere Pid is the process id Debugging MPI Programs Where pid is the process identifierIssue Support for showing unwind info Ask mode for set follow-fork-modeSerial mode for set follow-fork-mode Debugger response to a program call to fork or vfork is ask Command to Search for a Pattern in the Memory Address Space Printing CFM and PFS registers String value. The character pattern must be enclosed Parameter is mandatory when end-addressis notSpecifies the length of the memory address range. This Within double quotes. This parameter is mandatory Example 14-1 Sample Output for the find command Str0 Specifies the starting address Using the /max-countparameterUsing the /size-charparameter Specifies the pattern expr1 Debugging Core Files Generating core files with packcore /unpackcore/getcore Support for the info target Command When starting from the shell prompt Support for the dumpcore commandWhen starting from the HP WDB command line Enhancements to the dumpcore command Info rtti address When starting from shell promptSupport for display of run time type information Sample Output Exec-path updownpathindex aliased to ep Info exec-path summaryInfo global-exec-path summary Sample Debugging Session Example Illustrating Execution Path RecoverySample Program Command to Unwind Beyond 10000 Frames Aborting a Command Line Call Invoking GDB Before a Program Aborts Deferred watchpoints Instruction Level SteppingEnhanced support for watchpoints and breakpoints Hardware watchpoints Rbp Support for procedural breakpointsSupport for template breakpoints Rdp Using shared library as main program Debugging support for shared libraries Privately mapping shared libraries Setting Deferred Breakpoints in Shared LibraryUsing catch load Selectively Mapping Shared Libraries As Private Opt/langtools/bin/pxdb -s on executable-name Debugging support for Decimal Floating Point data type Setting breakpoints in shared libraryEnhancement to the info shared Command Printing Decimal Floating point data types Handling Decimal Floating Point Data types Following are sample commands to print NaT registersPrinting NaT Registers Evaluating Decimal Floating Point data types Comparison Operations Assignment of Decimal floating point value to variableArithmetic Operations Printing type of Decimal Floating Point variable This prints the binary floating point value as oat Additional Support for binary floating point data typeSupport for Binary Floating Point constants f, l This prints the binary floating point value as double Enhanced Java Debugging Support Java Stack Unwind FeaturesLanguage support Gdb Subcommands for Java VM Debugging Gdb help java Info frame Frame command of GDB has been enhanced to interpret a JavaJava and native stack frames Stack frame Java attach mode debugging support Java corefile debugging support Enhanced support for C++ templates Syntax Support for debugging namespaces Support for fpreg data type on IPFSupport for Complex variables in HP C This is equivalent to executing Command for evaluating the address of an expressionViewing Wide Character Strings Support for output logging Support for dumping array in an Ascii file Displaying enumerators Support for steplast command for C and C++Support for Fortran array slices Support for debugging typedefs Getting information from a non-debug executable Break Call Cond Jump Return Print Set var Watch Whatis Debugging optimized codeBreak Call Clear Disassem List HP-UX Configuration-Specific Information 14.29.1.2 +O2/+O3/+O4/-ipo Debugging Optimized Code at Various Optimization Levels14.29.1.1 +O0 and +O1 +O2 or -O Following limitations apply when debugging optimized codeDebugging with Aries Debugging the application using GDB under Aries Limitations of GDB Support under Aries Detecting memory leaks using GDB under Aries Attaching GDB to an already running emulated process Visual Interface for WDB Starting and stopping Visual Interface for WDB Navigating the Visual Interface for WDB display Visual Interface for WDB GUI display Using the X-window graphical interface Specifying foreground and background colors For dterm, use the following Using the TUI modeChanging the size of the source or debugger pane Saving the contents of a debugging session to a file Using commands to browse through source filesEditing the command line and command-line history Loading source files Support for command line calls in a stripped executable Support for XDB commandsGNU GDB Logging Commands Stop in/at dbx commands Execute the chatr -B immediate executable command For 32-bit applications For 64-bit applications Command line calls to non-stripped librarySupport for debugging stripped binaries Printing of locals and globals in a stripped module Syntax Displaying the current block scope informationLinux support 242 Starting the TUI Invoke the debugger using a command like the followingHP-UX Terminal User Interface Main Automatically running a program at startup Screen Layouts Source pane Disassembly paneDisassembly pane appears when you issue the command Pane looks like this Source/Disassembly pane appears when you issue the command Source/Disassembly paneDisassembly/Register pane Source/Register pane appears when you issue the command Source/Register pane Cycling through the panes Use the commandsToggle split-screen mode Changing pane focus Fs regs Foc next Scrolling panes Changing the register display Changing the pane size Refreshing and updating the window By-function lists of XDB commands and HP WDB equivalents XDB to WDB Transition Guide Invocation commands Invocation commandsWindow mode commands Window mode commands File viewing commands File viewing commands Source directory mapping commands Data Viewing and modification commands Data viewing and modification commands Ll string Lm string Stack viewing commands Stack viewing commands Status viewing commands Status-viewing commandJob control commands Job control commands Overall breakpoint commands Overall breakpoint commandsAuxiliary breakpoint commands 10 Breakpoint creation commands Breakpoint creation commandsAuxillary breakpoint commands Breakpoint status commands 11 Overall breakpoint commands 12 Global breakpoint commands All-procedures breakpoint commandsGlobal breakpoint commands Bp bpt bpx dp Dpt Dpx Macro facility commands Assertion control commandsRecord and playback commands 13 Macro facility commands Signal control commandsMiscellaneous commands 14 Signal control commands XDB data formats and HP WDB equivalents Format of the print command is different in XDB and GDB16 Data format commands Decimal integer XDB special language operators and HP WDB equivalents 17 Macro facility commandsXDB location syntax and HP WDB equivalents 19 Special variables XDB special variables and HP WDB equivalents18 Special language operators 16.8.1 a Alphabetical lists of XDB commands and HP WDB equivalentsXDB variable identifiers and HP WDB equivalents 20 Variable Identifiers 16.8.2 B 22 B Through D 23 C through D 24 F through K Through K16.8.5 L 25 L Through P 26 M through P 27 Q through S Through S16.8.8 T 28 T Through Z 29 U through Z Symbols 30 Symbols Any string Control-C # text 280 Setting Command History Feature in GDB Setting the GDB PromptSetting Command Editing Options in GDB Controlling GDB Exits. You can access this list through history Control the settingsTo fname. This is the file where GDB reads an Expansion or through the history command Setting the GDB Screen Size Supported Number Formats Optional warnings and messages Show confirm Displays state of confirmation requests Optional messages about internal happeningsSet confirm on Show debug varobj Object debugging info Canned Sequences of Commands User-defined commands User-defined command hooks Command files To add source directories or Commands for controlled output Expressions Output formats 292 Using GDB under gnu Emacs Update display window accordingly Calls, like the GDB next command. Then update the displayExecute to next instruction, using the GDB nexti command GDB up command 295 296 Server prefix What is an annotation?GDB Annotations When printing a structure, GDB annotates it as follows Values Frame annotation begins with When printing an array, GDB annotates it as followsFrames Then comes Displays Annotation for GDB input Errors Information on breakpoints Invalidation notices Running the program Displaying source Annotations We Might Want in the Future Target-invalid 306 21.1 GDB/MI Command Syntax GDB/MI Interface Pragmatics Done running connected error exit21.1.2 GDB/MI Output syntax Value Const tuple list String Tuple → Simple examples of GDB/MI interaction Here is what happens if you pass a bad command21.2 GDB/MI compatibility with CLI Here is an example to evaluate an expression 21.3.1 GDB/MI result records 21.4 GDB/MI command description format21.3 GDB/MI output records 21.3.2 GDB/MI stream records 21.5 GDB/MI breakpoint table commands -break-after Command -break-condition command Corresponding GDB command is condition Corresponding GDB command is delete -break-delete command-break-disable command Corresponding GDB command is disable -break-enable command -break-info Command -break-insert command Result -break-list command Setting a watchpoint on a variable in the main function -break-watch commandCorresponding GDB commands are watch, awatch, and rwatch Exec-continue running gdb -data-disassemble command 21.6 GDB/MI Data manipulation Disassemble 3 instructions from the start of main There is no direct mapping from this command to the CLIDisassemble from the current value of $pc to $pc + -data-evaluate-expression command Display a list of the registers that have changed -data-list-changed-registers Command-data-list-register-names command On a PPC MBX board -data-list-register-values command To be read. Complex expressions containing embedded white -data-read-memory commandSpace should be quoted using the C convention Word-format Word-sizenr-rowsnr-cols aschar -display-delete command -display-disable Command -display-list command -display-enable command-display-insert Command -environment-cd command -environment-directory command -environment-path command 21.7 GDB/MI program control -environment-pwd commandCorresponding GDB command is pwd Show the current working directory -exec-continue command -exec-abort command-exec-arguments command Corresponding GDB command is finish -exec-finish command-exec-interrupt command Corresponding GDB command is interrupt Corresponding GDB command is next -exec-nextcommand Synopsis-exec-next-instruction command Corresponding GDB command is nexti Corresponding GDB command is return -exec-return command-exec-runcommand Synopsis Corresponding GDB command is run -exec-show-arguments command Example -exec-stepCommand Synopsis Corresponding GDB command is stepi -exec-step-instruction command-exec-until command Regular stepping Corresponding GDB command is until -file-exec-and-symbols command-file-exec-file command Corresponding GDB command is file -file-list-shared-libraries command -file-list-exec-sections command-file-list-exec-source-files command -file-symbol-file command Miscellaneous GDB commands in GDB/MI-file-list-symbol-files command -gdb-exitcommand Synopsis -gdb-version command -gdb-setcommand Synopsis-gdb-showcommand Synopsis -stack-info-depth command 21.9 GDB/MI Stack Manipulation Commands-stack-info-frame command -stack-list-arguments command Synopsis For a stack with frame levels 0 through -stack-list-frames command Show frames between lowframe and highframe Corresponding GDB commands are backtrace and whereFull stack backtrace Show a single frame Info locals in GDB, gdbgetlocals in gdbtk -stack-list-locals command-stack-select-frame command -symbol-info-file command 21.10 GDB/MI Symbol query commands-symbol-info-address command -symbol-info-function command -symbol-list-functions command -symbol-info-line command-symbol-info-symbol command -symbol-list-types command -symbol-type command -symbol-list-variables command-symbol-locate command -target-compare-sections command 21.11 GDB/MI Target Manipulation Commands-target-attach command -target-detach command Name of the section -target-download commandCorresponding GDB command is load At the end, a summary is printed -target-exec-status command -target-list-parameters command -target-list-available-targets command-target-list-current-targets command -thread-info command 21.12 GDB/MI thread commands-target-select command -thread-list-all-threads command -thread-list-ids command -thread-select command 21.14 GDB/MI variable objects 21.13 GDB/MI tracepoint commandsTracepoint commands are not yet implemented Description and use of operations on variable objects -var-create commandGDB/MI Operations -var-show-format command -var-delete command-var-set-format command -var-info-num-children command -var-info-expression command -var-list-children command-var-info-type command -var-show-attributes command -var-assign command -var-update command 360 Have you found a bug? How to report bugsReporting Bugs in GDB Reporting Bugs in GDB How to report bugs 364 Installing GDB Package Compiling GDB in another directoryGdb-gdb-199991101/mmalloc Specifying names for hosts and targets To use the source in the directory dirname. configure Configure optionsSeparate directories. configure writes configuration Srcdir= dirname Target=target All available targets