Examining Source Files

When you load a target program, the source file is displayed in the source file display area. See Figure 2-2 “Source File Display ”.

Figure 2-2 Source File Display

An arrow symbol in the annotation margin indicates the current point of execution. The circled B symbol designates a breakpoint.

Ordinarily, the debugger sets breakpoints at the program's entry and exit statements and executes the program up to its entry statement. You can create and delete breakpoints by clicking with the left mouse button on a line number in the annotation margin.

You can search for text strings in the source by selecting Visit:Search or CTRL-S.

If the target program was compiled from a number of source files, you can display other files by selecting Visit:File() after entering the source file name in the (): input box.

In addition, you can use the environment command. You must enclose the source file name in double quotes. For example:

env "source_filename"

If you move a source file after compiling the program, the debugger may be unable to find the source file. It will issue the warning: Unable to access object. Select File:Add Source Directories or use the property sdir command to put the source file in the debugger's search path.

Also, the source will not appear if the main program is not debuggable (even if there are debuggable modules within the target program). A message like the following may appear during startup:

(Warning) end.o has not been linked in.
(Warning) Notification of dynamic loader events
          will be unavailable.
Executing image in process 8981: "/home/smith/a.out".
Stopped at: $START$ (00001894)

However, you can view debuggable modules by selecting Visit:Environment(), Visit:File() or using the environment command. Specify 'source_filename', which is the leaf name (enclosed with double quotes) of the source file of a debuggable module.