I am working my way through the book Linux Device Drivers, 2nd Ed, and came upon a problem with the first example program, a simple module that prints "Hello World!" from the console. G++ doesn't recognize the header I used, as I believe it isn't in the search path. The header in question is linux/module.h. I need a way to see the header search path for g++, and a quick browse through info g++ didn't seem to help much. Does anyone know how to view and edit the search path for G++? Thanks in advance.

Post your source code.

Ok. Here it is:

#define MODULE
#include <linux/module.h>

int init_module()
{
printk("<1>Hello, World!\n");
return 0;
}

void cleanup_module()
{
printk("<1>Goodbye, Cruel World!\n");
}

looking at the book...
why dont you use gcc (as the book says):

How stupid of me! I will try that and report the results.

Okay. I made it into a .c file and compiled it with gcc as described in the book. Now, I get a new error. Here is how it went.
gcc -c hellomodule.c
insmod ./hellomodule.o
kernel-module version mismatch
./hellomodule.o was compiled for kernel version 2.4.20
while this kernel is bersion 2.4.20-6.

I compiled this on my own machine, so what is going on?

Aha! I found the problem! Now my question should be, "How do I disable kernel versioning for the 2.4.20 kernel? Thanks in advance.

Add the following to your gcc command line. It appears to fix the error for me. There will still be a warning about there being no license and therefore it might taint the kernel, but the kernel version problem seems to go away.

(You might need to put some version information after linux in the path. Search your filesystem to see what the correct path would be.)
-isystem /usr/src/linux/include

This is the command line that worked for me in the hello world module from "Linux Device Drivers" 2nd Edition. ( I defined __KERNEL__ and MODULE in the code.)
gcc -c -isystem /usr/src/linux/include hello.c