Computer Music and the Linux Operating System: A Report From the Front

The purpose of this article is to introduce readers to Linux and to describe the factors that make this operating system attractive to computer musicians. I have divided this exposition into two main parts. The first describes and assesses Linux as a general platform for computing. The second, longer section focuses on Linux's audio and music capabilities. In that section, a historical overview precedes a necessarily brief account of the Linux audio software base, followed by a prediction for the near future of Linux audio development and the acceptance of Linux for music applications.

A General Introduction to Linux

Many readers of this journal will need no introduction to Linux, but for the rest a brief description is in order. I will first review Linux in general terms, outlining its advantages as well as aspects that historically have been of concern. The remainder of this article will then describe in detail the considerations specific to audio and music.

Linux is a UNIX-like operating system designed to provide computer users with a free system comparable to traditional (and usually expensive) UNIX systems such as IBM's AIX, Sun's Solaris, or SGI's IRIX. "Free" here means that the system software itself is freely available at no cost, with free access to the source code, and with the assurance that anyone's development of the system benefits everyone else who develops or uses the system. Linux is compliant with the Portable Operating System Interface (POSIX), a standard of the Institute of Electrical and Electronics Engineers (IEEE).

The system kernel was developed in the early 1990s by Linus Torvalds at the University of Helsinki in Finland, and the system was essentially completed by making use of components developed for GNU (a recursive acronym for GNU's Not UNIX), which itself is a project of Richard Stallman's Free Software Foundation. Other notable contributions toward a complete system include the X Windows System (a client-server windowing engine) from the XFree86 organization, and networking tools and utilities from Berkeley Standard Distribution (BSD) UNIX. Originally designed for Intel's i386 processors, Linux now runs on many other CPUs and platforms, including the PowerPC, 64-bit Alpha systems, IBM's S/390, various embedded systems, and even hand-held machines (palm-tops).

It should be noted that many users (and some distributions) refer to the platform as "GNU/Linux" in recognition of the Free Software Foundation's significant contribution to the system. Strictly speaking, Linux is only the kernel, whereas most of its surrounding system software has indeed come from the GNU project's efforts.

Although the Linux kernel source code is in fact available at no cost, most new users begin their Linux experience by purchasing a software-plus-manual plus-support bundle called a Linux distribution. A distribution is normally a complete system including the X11 graphics and windowing system, a robust TCP/IP networking subsystem, and broad support for hardware extensions. Distributions also typically include a wealth of applications, utilities, and programming tools far in excess of comparable commercial systems. Linux itself is legally protected by the remarkable "copyleft" provisions of the GNU Public License (GPL), but available applications for Linux may be covered by any one of a variety of licenses ranging from freeware with absolutely no restrictions to commercial offerings protected by the end-user license agreements (EULA) commonly associated with off-the-shelf software. The great significance of the Linux/GPL marriage lies in the stipulation that any source-level modifications to the system must in turn be freely available upon redistribution. By establishing a source-code base that is publicly open and extensible by contributors, Linux has developed rapidly since its initial public release. Distributions are now available commercially from a number of high-profile vendors such as Red Hat, Mandrake, and SuSE, and extensive documentation about Linux is available online and in print.

The Linux applications software base has benefited from a rich inheritance of tools and utilities designed for UNIX computing environments, including sophisticated packages such as the Emacs text editor, the X11 windowing system, and the...