- Development of Unix
- Early computing used a batch model.
- Submit a complete job to the computer.
- Get results later.
- No interaction.
- First interactive systems are called time-sharing.
- Multiple users connect to one computer.
- Users are nearby, connected by a simple cable. Not computer network.
- Compatible Timesharing System (CTSS) is usually given as the first
- Part of project MAC at MIT
- First released 1961.
- Started in 1964.
- Joint project of ATT, MIT and GE (which then made computers).
- Intended to create a computer utility.
- Users would have terminals in their homes, much as they had
- It's 1964. Phones are land-lines, and they come from ATT.
- Users would have
uses included online commerce and information searches.
- Fell behind schedule and ATT withdrew from the project in 1969.
- ATT Bell Labs
- Bell labs was the well-funded research lab of ATT. Multics was being
- Some researchers at Bell Labs, no longer working on Multics, wanted to
apply some of what they learned to build something small. (Multics
was a huge and complex system.)
- Ken Thompson wrote an experimental file system on a discarded
- The rest of the system sort of grew from there.
- From this, the group was able to purchase a
and later an 11/45.
- The C language was invented after 1970, and Unix was
re-written in C by 1973.
- Technological imperative.
- Shared system supporting multiple users.
- Communication by text command.
- Memory and disks were small, and magnetic tapes were important.
- Leaving Bell.
- Paper presented in 1973 in ACM Symposium on Operating Systems
Principles. Revised the Communications of the ACM, July 1974.
- Well received.
- Until 1982, ATT had status as a legal monopoly for long-distance
phone service in the US, but was forbidden to enter other businesses.
- So it gave Unix away rather than sell it.
- Very popular with major universities. One of particular
importance was UC Berkeley.
- When ATT was giving away Unix, it was largely non-commercial.
- Some companies offered support for a fee (ATT could not).
- The ATT monopoly was broken up in 1982. This freed ATT to sell
- They started charging significant license fees; before it was just
a handling fee.
- Many versions were developed and sold.
- While there were many versions, two primary streams.
- The ATT commercial stream, starting with System V Unix.
- The Berkeley stream, BSD for Berkeley Software Distribution.
- Use of either required paying fees to ATT for their code.
- Berkeley's Escape.
- Berkeley attempted to replace all ATT code and released versions
free of ATT license fees. First release, BSD Net 1 in 1988.
- ATT sued them in 1992
- Settled in 1994.
- Linus Torvalds first started creating a clone on Unix in
the summer of
1991. This becomes the Linux OS.
- If ATT hadn't sued BSD, Linus Torvalds would probably not be famous.
The suit delayed the growth of the free BSDs and gave Linux a chance.
- Various versions of BSD (which is a Unix descendant), and Linux
(which is a clone) are available for free.
- What's there?
- The kernel is the part properly called Linux.
- The kernel is the primary component of the OS.
- It provides the primary abstractions, such as processes,
file system, device drivers and network protocols.
- Linux is produced by a team of developers headed by Linus
- Basic utilities, including the command shell.
- Basic text-based programs for working with files, text
and configuring the system.
- Some written by the kernel developers.
- Most written by the Free
- We'll spend a lot of time with these.
- GUI support.
- The basic GUI support in most Linux systems is X-Windows,
originally from MIT.
- Usual versions are from the X.Org foundation.
- A newer system call Wayland has replaced X in some distos.
- There are several suppliers of desktops. (X-Windows supports
driving the screen and the interface devices; doesn't do much
- General applications from many sources.
- A Linux distribution collects the various needed parts and
combines them to make a usable system.
- Most distros are the same in the large things, but differ in
- Package management.
- All distributions must keep track of what software is installed.
- Different systems are used, but there are a few main ones.
- The Debian distribution and derivatives, including Ubuntu and
Mint, use Debian packages.
- The Red Had commercial products and related free distros use
the Red-Hat Package Manger (RPM).
- The Gentoo distribution installs everything by building from
source instead of pre-compiled binaries. It's emerge system
- Windowing systems.
- There is no single Linux desktop environment.
- Different distros may support different ones.
- Some distros (e.g., Red Hat) support several to choose from.
- Server-based distros are happy to install without one.
- Policies against certain types of software.
- Debian avoids software which is not open-source. This can be a
problem getting wireless to work.
- Fedora avoids certain software for what it believes are legal risks.
This particularly impacts multimedia software.
- Ubuntu is pretty catholic in this regard.
- In most cases, you an get those packages from third parties, but
it can be more effort.
- There are specialized distros for unusual environments or
History reference: Salus, Peter, A Quarter Century of Unix,