- 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.
- 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.
- 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.
- Distributors collect these parts and offer an install-able system.
many. Some biggies:
- Some distinctives.
- Package management.
- All distributions must keep track of what software is installed.
- Different systems are used. The details are beyond this course.
- 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.
- Generally, the packages are available from third parties anyway, but
that's more work.
- Distributions generally provide a bootable CD/DVD image which can be written to
- Boot the CD and you'll see an install icon.
- Procedures vary from there.
- Some are very automatic. Watch the progress bar and hope nothing breaks.
- Some require the user to execute the steps, so you can easily break it yourself.
- Tasks. A Linux install must somehow perform the following feats.
- Create a partition for the Linux file system.
- Partitions are divisions of a hard drive which can be used for different OS's.
- On a running system, the existing partitions usually use up all the the
- Even if your Windows file system has plenty of free space.
- The file system is inside the partition, and fills it.
- Generally, you must make space for the new partitions.
- Delete (destructively) an existing partition.
- Of course, your existing OS is toast.
- But if it just screwed up for th 487th time, it can feel great!
- A good option if you have an old computer around that's not
serving any other purpose. (Also provides a good excuse for why your
spouse shouldn't throw it out.)
- Shrink (non-destructively) an existing partition to free up disk space.
- There are free tools for this.
- Some installers offer it as an option.
- Always a risk that it will go sideways and trash the partition instead
of shrink it. I've never seen this happen, but there's always a first time.
- Add a disk.
- Install an additional internal hard drive, if possible. Not so common
an option these days.
- Use a USB disk, including possibly a thumb drive.
- Installers which offer this often seem to treat the installation as
permanent; you'll always have to use it on that machine.
- Format the new partition (or partitions) and write the software there.
- Install the boot loader.
- The boot loader is the software that initially loads the operating system
into memory and starts it running.
- If there are multiple operating systems installed, the boot-loader will let
you select which one to boot.
- The usual boot-loader for Linux is called grub.
- Grub is installed on one of your bootable hard drives.
- It can boot any Windows partitions as well as Linux.
- Random Links.
History reference: Salus, Peter, A Quarter Century of Unix,