C libraries in Linux

Copy from a book.

There are several C libraries to choose from. The main options are as follows:

• glibc: This is the standard GNU C library, available at h t t p ://w w w . g n u . o r g /s o ft w a r e /l i b c . It is big and, until recently, not very configurable, but it is the most complete implementation of the POSIX API. The license is LGPL 2.1.

• musl libc: This is available at h t t p s ://w w w . m u s l - l i b c . o r g . The musl libc library is comparatively new, but has been gaining a lot of attention as a small and standards-compliant alternative to GNU libc. It is a good choice for systems with a limited amount of RAM and storage. It has an MIT license.

• uClibc-ng: This is available at h t t p s ://u c l i b c - n g . o r g /. u is really a Greek mucharacter, indicating that this is the micro controller C library. It was first developed to work with uClinux (Linux for CPUs without memory managementunits), but has since been adapted to be used with full Linux. The uClibc-ng library is a fork of the original uClibc project (h t t p s ://u c l i b c . o r g /), which has unfortunately fallen into disrepair. Both are licensed with LGPL 2.1.

• eglibc: This is available at h t t p ://w w w . e g l i b c . o r g /h o m e . Now obsolete, eglibc was a fork of glibc with changes to make it more suitable for embedded usage.Among other things, eglibc added configuration options and support forarchitectures not covered by glibc, in particular the PowerPC e500 CPU core.The code base from eglibc was merged back into glibc in version 2.20. The eglibc library is no longer maintained.