UClibc

uClibc - a Small C Library for Linux Erik Andersen andersen@codepoet.org

uClibc (aka µClibc/pronounced yew-see-lib-see) is a C library for developing embedded Linux systems. It is much smaller than the GNU C Library, but nearly all applications supported by glibc also work perfectly with uClibc. Porting applications from glibc to uClibc typically involves just recompiling the source code. uClibc even supports shared libraries and threading. It currently runs on standard Linux and MMU-less (also known as µClinux) systems with support for alpha, ARM, cris, e1, h8300, i386, i960, m68k, microblaze, mips/mipsel, PowerPC, SH, SPARC, and v850 processors.

If you are building an embedded Linux system and you find that glibc is eating up too much space, you should consider using uClibc. If you are building a huge fileserver with 12 Terabytes of storage, then using glibc may make more sense. Unless, for example, that 12 Terabytes will be Network Attached Storage and you plan to burn Linux into the system's firmware...

uClibc is maintained by Erik Andersen and is licensed under the GNU LESSER GENERAL PUBLIC LICENSE. This license allows you to make closed source commercial applications using an unmodified version of uClibc (Please consider sharing some of the money you make ;-). You do not need to give away all your source code just because you use uClibc and/or run on Linux. You should, however, carefuly review the license and make certain you understand and abide by it strictly.

For installation instructions, see the file INSTALL.

uClibc strives to be standards compliant, which means that most documentation written for SuSv3, or for glibc also applies to uClibc functions. However, many GNU extensions are not supported because they have not been ported, or more importantly, would increase the size of uClibc disproportional to the added functionality. There is some discussion of these differences in the "docs" directory.

Additional information (recent releases, FAQ, mailing list, bugs, etc.) can be found at http://www.uclibc.org/.

uClibc may be freely modified and distributed under the terms of the GNU Lesser General Public License, which can be found in the file COPYING.LIB.

Please Note:

There is an unwholesomely huge amount of code out there
that depends on the presence of GNU libc header files.
We have GNU libc compatible header files.  So we have
committed a horrible sin in uClibc.  We _lie_ and claim
to be GNU libc in order to force these applications to
work as their developers intended.  This is IMHO,
pardonable, since these defines are not really intended
to check for the presence of a particular library, but
rather are used to define an _interface_.  Some programs
are especially chummy with glibc, and may need this
behavior disabled by adding CFLAGS+=-D__FORCE_NOGLIBC

If you want to make special exceptions in your code which are
specifically for uClibc, you can make certain to include features.h,
and then have your code check for uClibc as follows:

    #ifdef __UCLIBC__
	    do_something_special();
    #endif

And most of all, be sure to have some fun! :-) -Erik