Unix/Linux basics0000

Operating systems labGergely Windisch

windisch.gergely@nik.bmf.huroom 4.12

http://nik.bmf.hu/gwindisch/os_2010

About the class - organization• 14 weeks - 4 hours / week• Tuesdays from 15:20 to 18:40• Attendance is not optional (surprise, surprise)

• except for the 6th of April• and when someone really does not want to come

• Grading– homework - necessary for taking the exam– exam - grade is given based on the score

About the class - topics• We are going to cover

– linux basics• commands• files, directories• permissions

– user management– program installation– shell scripting– GUI– services– for details, see unixclass.doc

Project assignment

• The students should create a small infrastructure consisting of at least three machines

• The goal is to have an application server and a separate database server set up, and then use the client to install a service to the application server.

Project assignment

• Three machines– Client (any desktop linux or unix will do)– Application server (web or something like that)– Database server

• Application server– Should serve static and dynamic content - apache, php etc.– install some freeware php application - wiki, cms, forum engine, blog, joomla, drupal - your

choice– needs to be accessible via ftp from the client machine

• Database server– should run *sql (my~, pl~, postgre~)– will serve all the data for the application server– needs to have ftp access– needs to have a firewall that rejects direct access from every machine except for the

application server• The servers should be console only (no GUI)• All the operating systems need to be different, at least one needs to be unix

– For example: Fedora for the client, opensolaris for the app server, Solaris for the DB

Project assignment

• What to hand in– The virtual machines (DVD, USB stick, whatever)– Documentation

• 3-5 pages• summary of the systems, usernames and passwords• screenshots from the working systems• description of the problems you have ran into (if any)

• Important dates– 23th of February - list of the systems to be used– 4th of May - due date

Unix - the beginning

• Operációs rendszer• 1969 - Bell laboratories• Ken Thompson, Dennis Ritchie, Brian

Kernighan (and many others)

Unix systems

• Single UNIX Specification - defines what needs to achieved to be called Unix– IBM AIX (6.1 - 2007 November)– HP-UX (HP-UX 11i v3 Update 4 - 2009 April)–Mac OS X (v10.5)– Sun Solaris (now called Oracle) (10 5/09 - 2009

May)

Unix-like system

• Systems without SUS certification can only be called Unix like– BSD (Net-, Free-, Open-)– Linux (Debian, Slackware, Gentoo, Ubuntu stb.)

Solaris

• Why Unix? (and not windows)– oh please…

• Why Unix? (and not Linux)– Stability, advanced technologies, reliability,

plannability (eg. zfs, DTrace)

• Why Solaris?– The only one that runs on Intel architecture :)

• Solaris 10 vs. OpenSolaris• http://www.sun.com/software/solaris/

Solaris vs OpenSolaris

• Solaris 10:– Closed development– Stable– Enterprise level support– CDE graphical interface

• OpenSolaris– Developed since 2005 - open soure– "test bed" of Solaris

OpenSolaris

• Sourcecode• Community• Distribution

Other OpenSolaris distributions• SXCE (SOlaris Express COmmunity Edition) - The original

OpenSolaris distributions, made by Sun (now Oracle)• Schillix - the first. http://schillix.berlios.de/• Belenix - interesting, it has more GUIs, not just gnome.

http://www.belenix.org/• NexentaCore - Cross between Ubuntu and OpenSolaris. Has all

the GNU tools, apt-get package management, uses the ubuntu repository install software.

• keresztezése. Benne van a teljes GNU eszközkészlet, apt-get csomagkezelő, az ubuntu repositoryt használja a telepítéshez.It also has zfs, is able to create snapshots making it easy to restore the previous states after an upgrade that has gone badly

• MilaX: Nice little distribution. Aims for lightness. http://milax.org

Unix history • It was created around the 70’s for mini computers. It has spread to

the mainframes, workstations and then to personal computers• Simplicity was always an aim• The kernel was written in C (almost from the beginning) -> new• The many flavors of Unix and the incompatiblity that came with it is

still around

• Multiple unix versions: good, because competition enhances there is no one accepted solution (incompatiblity)

• Standardization work, multiple standards (the important is „what”, not „how”)

• Commercially avalable Unix versions: Sun/Solaris, HP/HP-UX, IBM/AIX

• Interesting: Mac OS X (BSD based)

Multiuser, multitask operting system

Linux

• Born in 1991– Linus Torvalds – x86– Started life as a terminal app for minix

• Nowdays an alternative to Unix and Windows systems• Linux is not Unix, but similar• Unix like in appearance and programming API, different

under the hood• The kernel is not held by one company but is developed

by the community (with centralized management - Linus)

• The code base is developed by the community• Wide spectrum of supported hardware architectures• There are some pioneer solutions, but there are also

some weak spots compared to the „big” Unix versions (thread management in the 2.4 kernels for example)

Linux - distributions• Linux distributions– „A Linux distribution (also called GNU/Linux by some

vendors and users) is a member of the family of Unix-like software distributions built on top of the Linux kernel. Such distributions (often called distros for short) consist of a large collection of software applications such as word processors, spreadsheets, media players and database applications. The operating system will consist of the Linux kernel and, usually, a set of libraries and utilities from the GNU project, with graphics support from the X Window System. „ - Wikipedia

– http://upload.wikimedia.org/wikipedia/commons/8/8c/Gldt.svg

Linux – distros (cont’d)• Even more colorful than unix

– free and commercial as well• Most important commercial versions: RedHat and

Suse• Free versions: Debian and co. (debian based), Fedora

(RedHat based) and openSuse• Live CD try without installation– Knoppix: http://www.knoppix.org/ (Debian GNU/Linux)– Demolinux: http://www.demolinux.org/ (Mandrake)– More at:

http://en.wikipedia.org/wiki/Live_CD

Useful links

• http://www.hup.hu – Hungarian Unix Portal– Only in hungarian for those of you who are

interesten in the language

• http://www.kernel.org – Place of the linux kernel

• http://www.distrowatch.com – home of practically all the distributions

Where can I practice?

• Downloading linux: – www.ubuntu.com, www.debian.org,

www.slackware.com, www.suse.de, en.opensuse.org, www.distrowatch.com

• VMWARE pre-built images:http://www.vmware.com/vmtn/appliances/directory/cat/45

Where can I get help?

• Everywhere!– The Hungarian Unix Portal:

http://hup.hu (again, for the eager minded)– Linux Knowledge Base and Tutorial:

http://www.linux-tutorial.info– http://en.wikipedia.org/wiki/Linux– Linux Shell Scripting Tutorial:

http://www.freeos.com/guides/lsst/– http://www.google.com

The graphical world…

• Distributions– RedHat (www.redhat.com)– Ubuntu (www.ubuntu.com)– Debian (www.debian.org)– Slackware (www.slackware.com)–Mandriva (www.mandriva.com)– Suse (opensuse.org)– Let’s look at some of them

Linux basics

• Linux is like Unix – API and the command line is unix compatible

• As far as we get into the subject, all the distros are the same

• Makes no difference which one we install

Linux basics (cont’d)

• Multiuser: we do not rule the whole machine – just one session (many concurrent users)

• Authentication before being able to do anything – user + password

• System access is restricted – we can only modify those to which we have the permissions

• Simple users cannot change (break) the system (for that would affect others)!

• Because of the multiuser environment, linux is somewhat different to other pc operating systems: one machine, multiple terminals. Still apparent today: virtual console

• Text based mode (shell) and graphical interface (X)• GUI is spreading like mushroom after the rainy season - but

the main interface for setting the system up is still the console.• Terminal access via TCP/IP, earlier it was via RS-232 (serial

port)• In a PC based desktop solution the machine and the view isn’t

separated, however it is still separated underneath (modularity)

root user

• Every OS needs a superuser who can access everything, set things up

• In Unix, the role is called root. Root has total control over the machine

• There can only be one root, it’s task cannot be given to multiple users

• Possible solutions: – sudo, RBAC (hasn’t really caught on)– Security Enhanced Linux

Install'em

• We will be using Vmware workstation– Player, server works just as well

• New virtual machine– choose type– specify hardware– specify install media

• We have a whole bunch, try them all