动态库查找程序 ld.so, ld-linux.so (from man ld.so):
The programs ld.so and ld-linux.so* find and load the shared libraries needed by a program, prepare the program to run, and then run it.
Linux binaries require dynamic linking (linking at run time) unless the -static option was given to ld(1) during compilation.
The program ld.so handles a.out binaries, a format used long ago; ld-linux.so* handles ELF (/lib/ld-linux.so.1 for libc5, /lib/ld-linux.so.2 for glibc2), which
everybody has been using for years now. Otherwise both have the same behavior, and use the same support files and programs ldd(1), ldconfig(8) and
/etc/ld.so.conf.
When resolving library dependencies, the dynamic linker first inspects each dependency string to see if it contains a slash (this can occur if a library pathname
containing slashes was specified at link time). If a slash is found, then the dependency string is interpreted as a (relative or absolute) pathname, and the
library is loaded using that pathname.
If a library dependency does not contain a slash, then it is searched for in the following order:
o (ELF only) Using the directories specified in the DT_RPATH dynamic section attribute of the binary if present and DT_RUNPATH attribute does not exist. Use of
DT_RPATH is deprecated.
o Using the environment variable LD_LIBRARY_PATH. Except if the executable is a set-user-ID/set-group-ID binary, in which case it is ignored.
o (ELF only) Using the directories specified in the DT_RUNPATH dynamic section attribute of the binary if present.
o From the cache file /etc/ld.so.cache, which contains a compiled list of candidate libraries previously found in the augmented library path. If, however, the
binary was linked with the -z nodeflib linker option, libraries in the default library paths are skipped. Libraries installed in hardware capability directo‐
ries (see below) are preferred to other libraries.
o In the default path /lib, and then /usr/lib. If the binary was linked with the -z nodeflib linker option, this step is skipped.
如果使用 gcc 编译程序， -L 后面的地址将会最后寻找。
动态库依赖关系查看程序 ldd
ldd prints the shared libraries required by each program or shared library specified on the command line.
#使用范例
ldd /bin/cat
linux-vdso.so.1 (0x00007fff9a1ff000)
libc.so.6 => /usr/lib/libc.so.6 (0x00007f4e177ae000)
/lib/ld-linux-x86-64.so.2 (0x00007f4e17b5b000)
动态库地址管理程序 ldconfig
# 查看当前 ld cache 中的所有库文件
ldconfig -p
# 重建 cache
sudo ldconfig -v
# 查看当前 ld 的搜索路径
ldconfig -v 2>/dev/null | grep -v ^$'\t'
/usr/lib32:
/opt/qt/lib:
/usr/lib: