- UNIX is a heavy-weight operating system for big computers
- UNIX is complicated
- UNIX is hard to use
- UNIX has been created by SUN, IBM, HP, and other large companies
- UNIX is monolithic
- UNIX was developed on small machines and became popular on the "killer micros". UNIX dialects now run on everything from a PDA to supercomputers.
- UNIX is based on simple and elegant principles (but has added some cruft over the years).
- UNIX is not particularly hard to use (compared to the power it gives to the user), but has a reasonably steep learning curve. It's not a "show-me" operating system, but a "tell me" operating system.
- UNIX has been created in a research environment, and much of it has been developed in informal settings by hackers. Much of the impetus for UNIX comes from free versions (Linux, NetBSD, OpenBSD, FreeBSD), although many companies contribute to its development.
- Many UNIX kernels are monolithic, but the UNIX system is extremly modular.
- First portable operating system (NetBSD: 18 processor architectures, 50 computer architectures).
- Written in a "high-level" language (C).
- Small (for what it does):
- Recent LINUX kernel: 2.4 million LOC (1.4 million for driver, 0.4 million architecture-dependent, 16 ports
- Windows 2000: Estimates range from 29 million to 65 million LOC, 1.5 architectures
- Modular (though often on a monolithic kernel)
- Separate windowing system (X) and window managers
- Various Desktop-Solutions (CDE, KDE, Gnome)
- Toolbox-philosophy: Combine (lots of) simple tools
- Underneath: Strong and simple abstraction (everything is a file)
- See also http://www.levenez.com/unix/
- Read the first paragraph of
The Rise and Fall of the Roman Empire again, with the following
phrase replacements:
Rome => UNIX town => operating system Italy => Bell labs years => months wars => versions United States => UNIX implementations government => kernel Romans => UNIX developers English => Java Spanish => C++ French => Ada
- Pragmatic high level language:
- Handles characters, numbers, addresses as implemented by most computers
- Small core language, much functionality provided by libraries (mostly in C!)
- Compilers are easy to write
- Compilers are easy to port
- Even naive compilers produce reasonably decent code
- Hacker-friendly
- Straightforward compilation (nothing is hidden)
- Compact source code (fewer keystrokes, fast to read)
- Typed, but not a bondage-and-discipline language
- Adequate support for building abstractions
- Structures (composing objects), unions, enumerations
- Arrays and pointer
- Support for defining new types
Back row:
Ken Thompson
- B, UNIX;
Denis Ritchie
- C, UNIX;
Brian Kernighan
- awk
Middle row:
Bill Joy
- vi, BSD, SUN;
James Gosling
- emacs, Java;
Eric Allman
- sendmail;
Jon Postel
- Internet
Front row:
Richard Stallman - FSF, GNU;
Linus Torvalds - Linux;
Alan Cox
- Linux, Redhat;
Avie Tevanian
- OS X