The GNU C Library

Any Unix-like operating system needs a C library. The GNU C library is used as THE C library in the GNU system and most systems with the Linux kernel.

• libc6 = glibc: version 2 of the GNU C Library, and the sixth major version of the Linux C library.
• libc5: the first version of the Linux C Library based on ELF.
• libc4: based on the a.out binary format.

It provides:

ldconfig

Configure dynamic linker run-time bindings.

ldd

Print shared library dependencies.