In some beautiful days, we wonder how GCC search for standard libraries like libstdc++.so. Cool! It really matters for those guys who works on developments of new standard libraries. They want to have both versions of libraries at the same time. It is a controversial topics. After I googled it, here is the summary I found.
There are two definitions denoted as ld you need to differentiate: linker in GCC and loader in linux. ld can refer to ld (GNU linker) (at compiling time). It can also refer to loader ld.so in linux (at running time).
How to know search path during linking and running time?
During linking of GCC, we can use this instruction:
1/ You can do this by executing the following command:
ld --verbose | grep SEARCH_DIR | tr -s ' ;' \\012
2/ gcc passes a few extra -L paths to the linker, which you can list with the following command:
gcc -print-search-dirs | sed '/^lib/b 1;d;:1;s,/[^/.][^/]*/\.\./,/,;t 1;s,:[^=]*=,:;,;s,;,; ,g' | tr \; \\012
The answers suggesting to use ld.so.conf and ldconfig are not correct because they refer to the paths searched by the runtime dynamic linker (i.e. whenever a program is executed), which is not the same as the path searched by ld (i.e. whenever a program is linked).
The most important keynote: GCC search -L paths first, then the default library (i.e, 2 first, then 1).
During run-time:
ldconfig -v 2>/dev/null | grep -v ^$'\t'
