|libc.so.*||The dynamically-linked C library (optional)|
|ld*||The execution time linker/loader (optional)|
If a C preprocessor is installed, /lib/cpp must be a reference to it, for historical reasons.[footnote 11]
"essential shared libraries and kernel modules"|
Loadable kernel modules (optional)
 Shared libraries that are only necessary for binaries in /usr (such as any X Window binaries) must not be in /lib. Only the shared libraries required to run binaries in /bin and /sbin may be here. In particular, the library libm.so.* may also be placed in /usr/lib if it is not required by anything in /bin or /sbin.
 The usual placement of this binary is /usr/lib/gcc-lib/<target>/<version>/cpp. /lib/cpp can either point at this binary, or at any other reference to this binary which exists in the filesystem. (For example, /usr/bin/cpp is also often used.)