Abstract: From 1992 to 1994, BSD which was UNIX developed at the University of California, Berkeley (UC Berkeley), found itself involved in a license-related lawsuit filed by ATT it is an open source software with publically available source code that can be freely redistributed. The name "Linux" originally referred to the kernel that makes up the core of the OS, however, entire OSs based on the Linux kernel are commonly referred to as Linux.Linux holds only a small share in the desktop PC market where accumulation and continuity of application software is critical. However, in the server OS market Linux competes with the likes of UNIX, represented by Solaris from Sun Microsystems,1 and with Windows Server from Microsoft, the reigning champion of the desktop PC market. The success of Linux made the term "open source" popular worldwide.Since its first official announcement by Linus Benedict Torvalds in October of 1991, Linux has been evolving at an astounding pace, achieving superior functionality in its lightness, high degree of freedom, and reliability. A few years later, in 1995, it was being used as a practical and stable OS (Leibovitch, 1999).At that time, Microsoft founder Bill Gates' famous "An Open Letter to Hobbyists"2 would epitomize source codes to be protected as intellectual property with usage rights to be granted to consumers for a fee. In the midst of this, Linux was provided free of charge and its source code was made publically available. These practices were greeted with surprise and sympathy, and considered as the reason for its success along with intuitive discussions (e.g., DiBona, Ockman, & Stone, 1999). Furthermore, for-profit enterprises such as Netscape, Apple, Hewlett Packard, and IBM subsequently began publicizing their adoption of the open source strategy, making their source codes available to the public (Hamerly, Pazuin, & Walton, 1999; Landry, 2000).However, the open source strategies of these for-profit enterprises were not as successful as that of Linux. The definitive reason for the success of Linux was in its miraculously perfect entry that filled the gaps left by preceding groups. This phenomenon could not be repeated even under ideal conditions of it being free of charge and open source.2. The Birth of UNIXUNIX was developed at ATT he rewrote the entire system for it to operate like an OS (Salus, 1994, chap. 1). This small-scale, light, and user-friendly OS was called UNICS, which later became UNIX.The first edition of the UNIX Programmer's Manual was published jointly by Thompson and Ritchie on November 3, 1971 to be used with the PDP-11/20 (Salus, 1994, chap. 13). The PDP-11 series hardware was quite limited in address and memory, which brought about a prominent characteristic of UNIX. …