ld-linux.so

TODO what does it do exactly. How is it called? By the kernel?

man ld.so

/lib64/ld-linux-x86-64.so.2 is the usual 64-bit version.

ld-linux.so* is the executable that does the dynamic loading for every executable.

As such, it cannot have any dependencies.

Its path is specified in the .interp section of ELF files, which Linux reads and uses to call ld-linux.

The default on Ubuntu 14.04 is /lib64/ld-linux-x86-64.so.2.

The program to be run is passed as an argument to ld-linux:

/lib64/ld-linux-x86-64.so.2 a.out

Then:

man execve

says that the path of the loader is stored in the elf file, and readelf -a shows a section devoted to it:

INTERP         0x0000000000000238 0x0000000000400238 0x0000000000400238
                0x000000000000001c 0x000000000000001c  R      1
    [Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]

On Ubuntu 16.04, provided by the libc6 package.

LD_DEBUG

TODO

LD_LIBRARY_PATH

You can also add to path with environment variables.

Don't rely on this method for production.

export LD_LIBRARY_PATH='/path/to/link'

ld.so

TODO what is it?

ld.so.conf

TODO. E.g. Ubuntu 16.04 mesa:

/usr/lib/x86_64-linux-gnu/mesa/ld.so.conf

/etc/ld.so.conf

TODO.

ldconfig

TODO