Linux seminar

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Linux seminar 1

• The philosophy behind Linux
• (how to see the machine)

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Why Linux?
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Why did we choose Linux?

• Linux is stable.
• No viruses.
• It doesn't cost us any money.
• We are free to do what we like with it.
• Open specs allow anyone to make stuff for it or
  fix it.
• Its flexibility rewards creativity.
• It's tricked out with goodies at no extra charge.

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Linux is stable

• The system is protected so that one person's
  mistake can't compromise the whole system.
• The design basics are more than thirty years old,
  which means the bugs have long since been fixed.

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Linux doesn't catch viruses

• The stable system keeps a mistake by one person
  from taking over the important things.
• Like SARS and the Irish Potato Famine,
  monoculture leads to catastrophe. Linux is a
  little bit different.

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Linux doesn't cost money

• We're po'
• Also known as 'free as in beer'
• No license fees
• No support costs
• No patent royalties
• Bill Gates is not our pimp.

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Linux lets us do what we like

• No license terms to worry about.
• We can copy it all we like.
• We can change anything we want to change.

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Linux has open specs

• Anyone can contribute to Linux
• Anyone with the ability to learn can change or
  improve Linux
• Linux will not go out of business

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Linux is flexible

• Flexible is good, because it lets us adapt to our
  cheap environment without having to throw money
  at it.
• People like the NSA have made their own because
  of this, and everyone benefits.

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Linux is the 'pimpmobile' of operating systems

• Most Linux distributions come along with extra
  software free of charge.
• Daemons
• Troubleshooting tools
• Development tools
• Games

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Linux has disadvantages

• Linux doesn't have as many software packages
  available.
• Linux doesn't have drivers for everything on the
  market.
• Multimedia support sucks.

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Daddy, where did Linux come from??
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What is Linux's ancestry?

• Geeks at ATT invented Unix.
• Other geeks at UC Berkeley improved on it.
• They got into a big fight when one group wanted
  to put the financial smack down on the other.
• From beneath the rubble of broken eyeglasses and
  discarded pocket protectors emerged BSD and
  System V (ATT) Unices.
• Solaris, AIX are System V Unices still around
  today.
• Darwin (MacOS X), FreeBSD, OpenBSD, NetBSD are
  BSD Unices still around today.
• Linux is their bastard love child.

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Where did Linux come from?

• A geek named Linus Torvalds got in a fight with a
  professor and wrote part of it for a class
  project.
• People egged him on, and he wrote the rest along
  with a growing group of mostly dateless geeks
  worldwide, including the pretentious egomaniac
  Richard Stallman, founder of the Free Software
  Foundation (GNU Software).
• Debian came from some people who thought Red Hat
  sucked and wanted something completely free and
  standards compliant.

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Verily, I say unto thee, Linux is like unto...
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Linux is standardized

• Linux, and Unices in general, are made up of
  standard parts that are well-defined.
• Standard things are good because they improve
  competition, and make it easy to cooperate.
• Lego bricks are standardized.
• Plumbing and gasoline are standardized.
• English is more or less standardized.
• Most tools and construction supplies are
  standardized.

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Unix is made of parts

• Lots of stuff in Linux is made of parts that fit
  together.
• The pipe symbol is your friend
• Streams
• Protocols
• File formats

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To maintain order, we have hierarchies or layers.

• Kernel, modules, processes form a kind of
  hierarchy of layers.
• Users and groups form a hierarchy.
• File permissions are expressed in layers.

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The kernel and procs hierarchy

• The kernel is the center of all things.
• The modules extend the kernel's awesome power.
• Daemon processes provide services.
• User processes are at your command.

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The hierarchy of users and groups

• The user root has absolute power.
• All other users have a subset of root's awesome
  power.
• Groups enable users to share power with each
  other.
• NT is better out of the box, but there are ways
  to make up for that.

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The blessed hierarchy of the filesystem tree.

• Files are arranged in unix like a tree.
• At the top of the tree is the 'root' directory,
  '/'
• Folders are called directories. They contain
  files.
• All disks and other filesystems get spliced into
  the tree so that it is all one big hierarchy.

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The trinities of file permissions

• You cannot stop root. It has all power.
• Read, Write, Execute
• User, Group, Other
• NT is better out of the box, but Linux has
  extensions that make up for it.

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Linux is a community

• Like a community, some equals depend on each
  other.
• e.g. Apache needs Tomcat, which needs MySQL,
  which needs DNS, which needs Networking, which
  needs Files.

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Summary of our first seminar

• We don't need a pimp to compute.
• Unix is Linux's ancestor and cousin. If you know
  Linux, you know Unix.
• In Linux you see lots of layers (like permissions
  and the kernel) and trees (the filesystem, and
  processes.) Being aware of them helps you to
  visualize the machine.
• Linux is the sum total of many individual parts
  from many different sources. Understanding the
  individual parts helps you to solve problems
  without needing customized software.
• Those pieces are standardized so that Linux will
  play well with others and remain consistent with
  itself.