Get started using the debugger DBX

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Dbx can be a very helpful debugger. It works on C, FORTRAN, and Pascal code. In order to use dbx, you must compile your code with the -g flag. This flag causes the compiler to include a symbol table that dbx needs. Type:

	man cc
	man f77
	man pc

for more details.

The basic list of dbx commands are:

run

Start execution of a program.

stop at line-number

Insert a breakpoint at the given line number. When a running program reaches a breakpoint, execution stops and control returns to the debugger.

stop in function-name

Insert a breakpoint at the first line of the named function. Commonly, the command stop in main is used to stop at the beginning of the program.

cont

Continue execution after a breakpoint.

print expression

Display the value of an expression.

step

Execute a single line in the program. If the current statement calls a function, the function is single-stepped.

next

Execute a single line in the program, but treat function calls as a single line. This command is used to skip over function calls.

list

List the source programs.

where

Print the list of currently active functions.

 

Summary

If you get a core dump:

1. (Re)compile with -g
2. Run (and get coredump)
3. dbx a.out core
4. "where" tells you on what line (or close to it) you died

For more information, type:

	% man dbx