GNU Libtool is a software development tool in the GNU build system that addresses software portability issues when compiling shared libraries from source code. It's a shell script that balances disparities between different computing platforms, specifically for commands that compile shared libraries. It provides a uniform command-line interface across various platforms and executes the platform's native commands.
Software portability is complicated by different operating systems handling shared libraries in various ways, with some platforms not using shared libraries. Issues like differing C compilers, missing library functions, and varying header file names can hinder creating a portable software program.
Libtool manages the creation of both static and dynamic libraries on Unix-like operating systems by abstracting the library creation process and concealing system differences, such as between Linux and Solaris. It streamlines compiling a program on a new system by encapsulating platform-specific dependencies and the user interface into one script. Porters can bypass reviewing low-level documentation for the shared libraries to be built and instead run a configure script. Libtool can be used by Autoconf and Automake, two other portability tools in the GNU build system, or independently.