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Oracle Solaris Studio 12.3: Debugging a Program With dbx     Oracle Solaris Studio 12.3 Information Library
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1.  Getting Started With dbx

2.  Starting dbx

3.  Customizing dbx

4.  Viewing and Navigating To Code

5.  Controlling Program Execution

6.  Setting Breakpoints and Traces

7.  Using the Call Stack

8.  Evaluating and Displaying Data

9.  Using Runtime Checking

10.  Fixing and Continuing

11.  Debugging Multithreaded Applications

12.  Debugging Child Processes

13.  Debugging OpenMP Programs

14.  Working With Signals

15.  Debugging C++ With dbx

16.  Debugging Fortran Using dbx

Debugging Fortran

Current Procedure and File

Uppercase Letters

Sample dbx Session

Running the Sample dbx Session

Debugging Segmentation Faults

Using dbx to Locate Problems

Locating Exceptions

Tracing Calls

Working With Arrays

Fortran 95 Allocatable Arrays

Showing Intrinsic Functions

Showing Complex Expressions

Showing Interval Expressions

Showing Logical Operators

Viewing Fortran 95 Derived Types

Pointer to Fortran 95 Derived Type

Object Oriented Fortran

Allocatable Scalar Type

17.  Debugging a Java Application With dbx

18.  Debugging at the Machine-Instruction Level

19.  Using dbx With the Korn Shell

20.  Debugging Shared Libraries

A.  Modifying a Program State

B.  Event Management

C.  Macros

D.  Command Reference


Debugging Segmentation Faults

If a program gets a segmentation fault (SIGSEGV), it references a memory address outside of the memory available to it.

The most frequent causes for a segmentation fault are:

Using dbx to Locate Problems

Use dbx to find the source code line where a segmentation fault has occurred.

Use a program to generate a segmentation fault:

demo% cat WhereSEGV.f
    INTEGER a(5)
    j = 2000000
    DO 9 i = 1,5
        a(j) = (i * 10)
    PRINT *, a

Use dbx to find the line number of a dbx segmentation fault:

demo% f95 -g -silent WhereSEGV.f
demo% a.out
Segmentation fault
demo% dbx a.out
Reading symbolic information for a.out
program terminated by signal SEGV (segmentation violation)
(dbx) run
Running: a.out
signal SEGV (no mapping at the fault address)
    in MAIN at line 4 in file "WhereSEGV.f"
    4                   a(j) = (i * 10)