# How to get /usr/local/include added to include path



## mathk (Jun 27, 2010)

Hi,

Gcc is not including the path  /usr/local/include. 
So is there a proper way of doing it or should I just use the -I or env variable?


----------



## adamk (Jun 27, 2010)

-I is the proper way   The gnu toolchain, from the base system, only looks in directories from the base system.

Adam


----------



## mathk (Jun 27, 2010)

Ok right thanks for your answer.
Maybe you could help me:

I have a library that install his header in /usr/local/include.
No I am writing a configure.ac that should check if the llibrary is there if not it should failed to configure.


```
AC_CHECK_HEADER(lightning.h, [], [AC_MSG_ERROR([You should install lightning firt])])
```

So what is the proper way of writing this condition?

Thanks


----------

