Re: What are GCC's "Standard system directories" on GNU/Linux?

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Sujet : Re: What are GCC's "Standard system directories" on GNU/Linux?
De : already5chosen (at) *nospam* yahoo.com (Michael S)
Groupes : comp.lang.c
Date : 05. Feb 2025, 23:08:23
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Organisation : A noiseless patient Spider
Message-ID : <20250206000823.00000480@yahoo.com>
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On Wed, 5 Feb 2025 18:46:22 -0000 (UTC)
Kaz Kylheku <643-408-1753@kylheku.com> wrote:

On 2025-02-05, Alan Mackenzie <acm@muc.de> wrote:
Hello, comp.lang.c.
>
In the GCC manual, section 3.16 "Options for Directory Search"
partially describes where, how, and in what order GCC finds
#include files when compiling.
>
It's the "partially" bit which is getting on my nerves.  The manual
section contains a priority list for finding #include files, but the
fifth item just vaguely states:
>
    5. Standard system directories are scanned.
>
.  Which directories are these?  Where is this documented? 
 
All that stuff depends on the GCC installation, and therefore cannot
be specified in concrete terms in a general document.
 
Unfortunately
 
  gcc -print-search-dirs
 
does not have info about the include file search directories. I'm
guessing that could have to do with the split between the compiler
and preprocessor.
 
Anyway, we can coax the information out of the preprocessing stuff,
by adding the -v option to gcc -E.
 

I find -M easier.

Try this:
 
$ echo | gcc -xc -E -v - 2>&1 | awk '/include.*search starts
here/,/End of search list/' #include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/i686-linux-gnu/7/include
 /usr/local/include
 /usr/lib/gcc/i686-linux-gnu/7/include-fixed
 /usr/include/i386-linux-gnu
 /usr/include
End of search list.
 
The above happens to come from a 32 bit Ubuntu 18 VM, that I maintain
for compiling for 32 bit Intel. (You cannot install that from
scratch; 32 bit support started to be deprecated after Ubuntu 16; I
created that VM by upgrading from 16.)
 
 



Date Sujet#  Auteur
5 Feb 25 * What are GCC's "Standard system directories" on GNU/Linux?5Alan Mackenzie
5 Feb 25 +* Re: What are GCC's "Standard system directories" on GNU/Linux?2Dan Purgert
5 Feb 25 i`- Re: What are GCC's "Standard system directories" on GNU/Linux?1Alan Mackenzie
5 Feb 25 `* Re: What are GCC's "Standard system directories" on GNU/Linux?2Kaz Kylheku
5 Feb 25  `- Re: What are GCC's "Standard system directories" on GNU/Linux?1Michael S

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