Backtrace

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 1. The program will continue running. Perform any actions necessary to reproduce the crash

A backtrace shows a listing of which program functions are still active. Since functions are nested when they are called, the program must record where it left one function, to jump into an inner one. It does this on the stack, which we dump for the backtrace,

By getting a backtrace at the point of a bug, a developer may be able to isolate where that bug is, because it will narrow down to the function, or even the line, that caused the erroneous behaviour.

Generation

Please ensure you have packages with debug symbols installed. You can do this by following the instructions at DebuggingProgramCrash.

  1. Make sure the GNU Debugger is installed.

    apt-get install gdb
  2. Start the program under control of gdb:

    gdb <program> 2>&1 | tee gdb-<program>.txt
    (gdb) handle SIG33 pass nostop noprint
    (gdb) set pagination 0
    (gdb) run <arguments, if any>
  3. The program will start. Perform any actions necessary to reproduce the crash
  4. Retrieve a backtrace of the crash:

    (gdb) backtrace
    (gdb) thread apply all backtrace
  5. Attach the complete output from GDB, contained in gdb-<program>.txt, in your bug report.

backtrace of an already running program

This applies to debugging i.e. panel applets.

  1. Make sure the GNU Debugger is installed.

    sudo apt-get install gdb
  2. Find the PID (process ID) of <program>:

    ps ax | grep <program>
  3. Start gdb:

    gdb | tee gdb-<program>.txt
    (gdb) attach <PID>
  4. Continue the <program>:

    (gdb) continue
  5. The program will continue running. Perform any actions necessary to reproduce the crash
  6. Retrieve a backtrace of the crash:

    (gdb) backtrace
    (gdb) thread apply all backtrace
  7. Attach the complete output from GDB, contained in gdb-<program>.txt, in your bug report.

Backtrace (last edited 2022-12-20 22:15:16 by sergiodj)