Analyze code in large systems

Hello. I am working on a large system written in C programming. I am not fully aware of the whole system. I get an error and I found which function is causing that error. Any ideas how I could find the code of that function?
In general, how to you usually "walk around" large systems and read the code easily?

Any ideas (grep maybe) using Linux/Unix systems are preferred :)

ctags? http://linux.die.net/man/1/ctags - emacs allows you to load a tags file and use it to find symbols.

Otherwise, "grep -r symbolname ." in the root of the source tree works quite well - unless of course some "clever" use of macros (in which case ctags will probably also fail).

--
Mats

vim+tags may be a choice.

I'm sure someone else in your organisation must have tried to find some code before. How do they do it? It's not usually a good idea to reinvent the wheel.

QuantumPete

After searching for a while here are the methods I found for reading/analyzing source code:

• Using an editor: Most text editors support regular expressions. Here is a guide for regular expressions in vim and a guide for regular expressions in emacs.
• Using the ctags tool: matsp already mention that in previous post.
• Code Searching with grep: Useful when working with large systems with many directories and files.
  
  
  Example 1:

  Code:

  ---

  grep -n -r  '^test' *

  ---

  will show the file and the line containing the definition for the function test.
  
  Example 2:

  Code:

  ---

  grep -n -r  'test' *

  ---

  will show both the definition and all uses.
  
  
  Example 3: The Linux Kernel Load Calculation
• Tools:
  
  
  The cscope tool: A vim tutorial.
  
  sourcenav tool
  
  
  

Please feel free to comment or suggest any more methods.

I know that some people might be aware of all these, but it might be useful for some beginners (like me for example:)).

If interested a good link to help address researching and analyzing a large database of source code and repositories is below

http://lxr.linux.no/