Note: The original is here.

• Who is root?
  • Root is the Superuser
    • Root has ultimate authority
    • Root is used to perform all administrative tasks
    • YOU are root
  • What is he talking about?
    • Using Root
      • How to be a player
        Err...administrator.
      • Using the root account
        • That which I tell you three times is true:
        • Use root only for administration,
        • Use root only for administration,
        • Use root only for administration!
      • Why? It's too easy to do too much damage to your system.
        • Try this: (no DON'T!)
          rm -rf . /*
        • Whoops! One extra space and now my system is dead!
      • What did he say?
        • Use root only for administration!!!
    • A Brief Tour
      • Where am I?
        • Wide Open Spaces

          /	- the root
          --> /etc	- configuration files
          --> /usr	- user programs
          --> /var	- log files and stuff
          --> /proc	- system info
          --> /tmp	- temporary files
          --> /home	- home directories
          --> /root	- root's home directory
          --> ...	- some other stuff

        • Important Stuff, etc.
          • /etc/passwd
            • - contains user accounts
            • can be edited by hand or with tools (see your distro's documentation for info on tools)
            • see the man page passwd(5) for the format
          • /etc/group
            • contains information about the groups of users on the system
            • users can be in many different groups
              • primary group specified in etc/passwd
              • other groups specified here
            • groups allow users to share files
          • /etc/fstab defines the drives you can access
          • /etc/modules.conf defines kernel module configuration
          • /etc/XF86Conf or etc/X11/XF86Conf is your X configuration file
          • /etc/rc.d holds system startup scripts used by init and and etc/inittab
        • What Happens When I Turn On My Computer?
          • Get the jumper cables Gertrude!
            • CLICK! Whirr...
              • Boot time involves the coordinated effort of many programs
              • LILO/MILO/SILO or something similar
              • The Kernel
              • init (the parent of all processes)
              • initscripts
            • boot:
              • What makes the boot prompt? The boot loader.
              • LILO (The LInux LOader) is used on x86 boxen.
              • LILO loads the first bits of the OS from disk and starts them running
              • Controlled from (you guessed it)
                /etc/lilo.conf
            • More Lilo
              • Changes to the config file are committed by running /sbin/lilo
              • The manpages and Linux HOWTOs detail its configuration
              • Quick tip: configure a backup kernel bootable to take the terror out of kernel upgrades
            • Now Booting The Kernel
              • Lilo starts the kernel loading for us
              • The kernel is the core of the operating system
              • As the kernel boots, it sets up the hardware on the system, allocates memory for its own use, and starts init running.
              • 'demesg' will show you the kernel's boot messages
          • Controlling Daemons
            • Daemons and Dragons
              • Init, Father Of all Processes
                • init is Process Number 1
                • init's job is to start other processes running
                • init's configuration file is called inittab
                • init starts all of the background programs that make your system useable (login, inetd, etc.)
              • Init Scripts
                • The init scripts tell init what to run
                • The scripts define a "runlevel"
                • Runlevels are conceptual states. They define what daemons are running.
                • Linux systems use 6 runlevels (numbered 1-6)
              • Common Runlevels
                • Common runlevels include:
                  • Runlevel 0: shutdown
                  • Runlevel 1: single user mode
                  • Runlevel 3: standard multiuser mode
                  • Runlevel 5: X Window mode
                  • Runlevel 6: reboot
                • see the manpage for init for more details about what runlevels do
                • BSD vs. SVR4
                  • Two forms of init scripts exist
                    • BSD
                    • SVR4 (Read that "System 5")
                  • BSD style init scripts are monolithic in nature (one main script per runlevel)
                  • SVR4 scripts use many small scripts, each responsible for its own little part
                  • SVR4 Style is now most common on Linux
                • BSD Layout
                  • BSD scripts live in the directory /etc/rc.d
                  • They are typically named rc#.d (where # is the runlevel)
                  • They contain all the commands to put a system in a given runlevel, but may call other scripts
                  • Slackware uses this style
                • SVR4 Style
                  • SRVR4 style has all of its scripts living in /etc/rc.d as well
                  • The main scripts all live in a subdirectory called init.d
                  • These scripts know how to start and stop one specific daemon
                  • Subdirectories called rc#.d contain links to the scripts as needed for that runlevel.
                • A Map of SVR4 Init Scripts
                  • /etc
                  • --> /rc.d
                    • --> rc.sysinit (system startup)
                    • --> rc (the main init script)
                    • --> rc.local (miscellaneous)
                    • --> init.d - thar be scripts here
                    • --> rc#.d - thar be symbolic links here
                • Script Startup
                  The scripts in /etc/rc.d/init.d take four possible parameters
                  • start: starts the job
                  • stop: stops the job
                  • status: reports on the job's status (running or not)
                  • restart: restarts the job
                    Hint: You can start these manually! Try:
                    /etc/rc.d/init.d/httpd restart
                • Scripts Mapped to Runlevels
                  • We map the scripts to runlevels through directories named rc#.d (where # is a number)
                  • We create a symbolic link (like a Macintosh alias or a Windows shortcut) to the script called S##name and/or K##name in the appropriate directory.
                  • The number determines the order in which things happen, lowest first.
                • Boot Process
                  • The script /etc/rc.d/rc.sysinit starts up the system. This mounts filesystems, etc.
                  • /etc/rc/rc.d/rc looks in the directory for the desired runlevel for scripts called S##name, and runs them all with the "start" parameter.
                  • /etc/rc/rc.d/rc.local is called
                • Changing runlevels
                  • We can change the runlevel of the system. Try: "init <runlevel>"
                  • First we stop the stuff in the current runlevel. All of the K##name scripts are executed with the "stop" paremeter.
                  • All of the things to start in the new runlevel are started just like with the boot process.
                  • /etc/rc/rc.d/rc.local is run
                • Special Runlevel Changes
                  • When we call "shutdown -r now" we're really just changing to runlevel 6.
                  • Calling "halt" is really just switching to runlevel 0.
                  • Calling "shutdown now" or saying "init 1" is puts us in single user mode.
                  • We're at a root prompt.
                  • Almost no daemons are running.
                  • Good for maintenance.
                • Confused Yet?
                  • There are several good tools to help you out (and once you get the hang of it you'll really like it)
                  • Red Hat comes with 'tksysv' which gives you a nice interface to everything (in X)
                  • Other good ones exist. Look on Fresh Meat.
          • Quickly: X
            • You are in a maze of twisty passages all different.
              • A Brief Map
                • X provides the windowing system for your machine
                • X is a pain in the ass to configure
                • X's configuration file is /etc/XF86Conf or etc/X11/XF86Conf
                • X lives in /usr/X11R6
                • You run an X server which must support your card
              • Configuring The Bugger
                • An X configuration tool is provided by most distributions; see your documentation.
                • For common hardware, this can make things go very smoothly
                • 'XF86Setup' comes with X and provides a text-based, question and answer style setup tool
              • It Won't Work
                • If you get stuck, check the documentation on http://www.xfree86.org
                • Read the HOWTO (more on that in a second)
                • Ask someone on the Plug mailing list
          • Getting Help
            • Help! Help! I'm being repressed!
              • Quick Links
                • Join the Plug Mailing list, instructions on the page http://expert.cc.purdue.edu/~plug/
                • The Linux Documentation Project
                  • Manuals, links, and HOWTOs
                    http://metalab.unc.edu/linux/
                • Freshmeat
                  • News about software releases
                    http://www.freshmeat.net/
                • Slashdot
                  • Good general information on geek stuff
                    http://slashdot.org/
                • Unix Review's Performance Computing
                  • http://www.performancecomputing.com/
                    Free subscriptions here!
                • Don't forget the 'man' pages and info manuals
              • Slide 38: Questions?
      That's All Folks! (-: