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From Giau Nguyen Ngoc:
Originally, Unix was meant to be a programmer's workbench to be used for developing software to be run on multiple platforms more than to be used to run application software. The system grew larger as the operating system started spreading in the academic circle, as users added their own tools to the system and shared them with colleagues.Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. These concepts are collectively known as the Unix philosophy. Kernighan and Rob Pike summarize this in The Unix Programming Environment as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves."Unix operating systems are widely used in servers, workstations, and mobile devices. The Unix environment and the clientserver program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers.