Debugging Core Files Using HP WDB

Commands For Core File Debugging

This section discusses the commands for debugging core files.

Invoking WDB to Debug Core Files

To invoke the debugger on the core file, enter one of the following commands:

• At the HP-UX prompt:

$ gdb a.out core

$ gdb a.out -c core

$ gdb -c core

• (Or) At the gdb prompt:

(gdb) core core

(where a.out is the executable that dumped core.)

If the executable path is not provided, the debugger selects the invocation path of the process

that generated the core file. The invocation path information is stored in the core file. If the

invocation path is a relative path, you must specify the executable to debug the core file.

On invoking the core file debugging session, the debugger displays the following information

(depending on the debug information available):

• The signal that caused the core file

• The cause of the un-handled signal

• The instruction at which this signal occurred

• The function name and the parameters of the function in which this instruction resides

• The source line information

The following example illustrates the output from the debugger on invoking a core file debugging

session:

Core was generated by `a.out'.

Program terminated with signal 11, Segmentation fault.

SEGV_ACCERR - Invalid Permissions for object

#0 inline generate_core_dump () at a.c:11

11 printf ("Generated coredump\n");

(gdb) bt

#0 inline generate_core_dump () at a.c:11

#1 0x4000a00:0 in inline foo () at a.c:30

#2 0x40009b0:1 in main () at a.c:37

Setting the Path for the Relevant Shared Libraries

The core files do not carry information about the exact version of shared libraries that were in

use at the time of core dump. Analyzing a core file without the correct versions of shared libraries

can produce misleading results. Hence, you must provide information about the relevant shared

libraries before initiating a core file debugging session. All the required libraries must be copied

to a temporary location on the system where you are debugging the core file (if it is different

from the system where the core file was generated).

The executable and the core file inherently carry information about the list of shared libraries

that were loaded at the instant of core dump. However, this list of shared libraries is referenced

by pathnames (the invoked path of the shared libraries on the system where the core dump

occurred).

Commands For Core File Debugging 15