What is the difference between /lib/i386-linux-gnu/libc.so.6, /lib/x86_64-linux-gnu/libc.so.6 and /usr/lib/x86_64-linux-gnu/libc.so?

Question

I installed Matlab in my Linux Mint 14 Nadia (a uname -a shows: Linux Ideapad-Z570 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:31:23 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Answer 1

To find which one to use, you have to first find the order that ld (the linker) uses to find libraries, like so:

ld --verbose | grep SEARCH

For me it gave me this output:

SEARCH_DIR("/usr/x86_64-unknown-linux-gnu/lib64"); SEARCH_DIR("/usr/x86_64-unknown-linux-gnu/lib"); SEARCH_DIR("/usr/lib"); SEARCH_DIR("/usr/local/lib");

This means that on my computer, ld looks in these directories, in order:

1. /usr/x86_64-unknown-linux-gnu/lib64
2. /usr/x86_64-unknown-linux-gnu/lib
3. /usr/lib
4. /usr/local/lib

So if libc was in /usr/x86_64-unknown-linux-gnu/lib64, and libc was also in /usr/lib, it would use the /usr/x86_64-unknown-linux-gnu/lib64 version, because it was listed first.