Find the default library paths and default headers include paths

[luca-ub-1993]

I'm on an Ubuntu 22.04 system and I'm working with C language and libraries.

I know ( from different books, included "The Linux Programming Interface" by Kerrisk ) that this algorithm is used when looking for runtime shared libraries locations ( I just omitted the preloaded libraries for the sake of simplicity ) :

When RUNPATH field is specified (i.e. DT_RUNPATH is non-empty)

1 ) LD_LIBRARY_PATH
2 ) runpath (DT_RUNPATH field)
3 ) ld.so.cache
4 ) default library paths (/lib and /usr/lib)

In the absence of RUNPATH (i.e. DT_RUNPATH is empty string)

1 ) RPATH
2 ) LD_LIBRARY_PATH
3 ) ld.so.cache
4 ) default library paths (/lib and /usr/lib)

The problem is that most books say that generally speaking the default library paths are /lib and /usr/lib but they don't mention HOW I CAN GET THE EXACT DEFAULT LIBRARY PATHS FOR MY SYSTEM. What command can I use on my Ubuntu 22.04 system ?

What about the default headers include paths ? What command can I use the get them ?

And finally what is the specific algorithm used in my ubuntu system when dealing with "headers.h" vs <headers.h> ?

[coffeecat]

Another duplicate. @luca-ub-1993, please do not post duplicates in different parts of the forum - you posted three identical posts altogether. This is not good netiquette, it dilutes community effort and causes confusion.

Thread closed. The still open thread is here: https://ubuntuforums.org/showthread.php?t=2494627