What is Unix

1
What is Unix?

• A multi-user networked operating system
• Handles processes, memory, files, input/output
• Multi-user
• Every user has different settings and permissions
• Multiple users can be logged in simultaneously
• The internet was designed on it, thus networking
  is an intrinsic part of the system

2
Unix vs. Linux

• Age
• Unix born in 1970 at ATT/Bell Labs
• Linux born in 1992 in Helsinki, Finland (Linus
  Torvalds)
• Sun, IBM, HP are the 3 largest vendors of Unix
• These Unix flavors all run on custom hardware
• Linux is FREE!
• written for Intel/x86, but runs on many platforms
• one of the most prominent examples of free
  software and of open-source development
• all source code is available to the public and
  anyone can freely use, modify, improve, and
  redistribute it.

3
What is Linux ?

• In the narrowest sense, the term Linux refers to
  the Linux kernel
• It is commonly used to describe entire Unix-like
  operating systems (aka. GNU/Linux) that are based
  on the Linux kernel combined with libraries and
  tools from the GNU project and other sources
• Most broadly, a Linux distribution bundles large
  quantities of application software with the core
  system, and provides more user-friendly
  installation and upgrades.

4
Growth of Linux

• Initially, Linux was primarily developed and used
  by individual enthusiasts.
• Linux has gained the support of major
  corporations such as IBM, Sun Microsystems,
  Hewlett-Packard, and Novell for use in servers
  and is gaining popularity in the desktop market.
• Analysts attribute this success to its vendor
  independence, low cost, security, and
  reliability.
• Linux was originally developed for Intel 386
  microprocessors and now supports all popular
  computer architectures.
• It is deployed in applications ranging from
  embedded systems to personal computers to
  supercomputers.

5
The Command Prompt

• Commands are the way to do things in Linux
• A command consists of a command name and options
  called flags
• Commands are typed at the command prompt
• In Linux, everything (including commands) is
  case-sensitive

prompt ltcommandgt ltflagsgt ltargsgt
frank ls al unix-tutorial
6
Getting help with man

• man (short for manual) documents commands
• man ltcmdgt retrieves detailed information about
  ltcmdgt
• man k ltkeywordgt searches the man page summaries
  (faster, and will probably give better results)
• man K ltkeywordgt searches the full text of the
  man pages

frank man k password passwd (5) - password
file xlock (1) - Locks the local X display
until a password is entered frank passwd
7
Directories

• In Linux, files are grouped together in other
  files called directories, which are analogous to
  folders in Windows
• Directory paths are separated by a forward slash
  /
• e.g. /home/frank/Lab01
• The hierarchical structure of directories (the
  directory tree) begins at a special directory
  called the root, or /
• Absolute paths start at /
• Relative paths start in the current directory
• e.g. Lab01/test.c (if youre currently in
  /home/frank)
• Your home directory is where your personal
  files are located, and where you start when you
  log in.

8
Directories (contd)

• Handy directories to know
• Your home directory
• .. The parent directory
• . The current directory
• ls
• LiSts the contents of a specified files or
  directories (or the current directory if no files
  are specified)
• Syntax ls ltargsgt
• pwd
• print Working Directory

9
Directories (contd)

• cd
• Change Directory (or your home directory if
  unspecified)
• Syntax cd ltdirectorygt
• e.g. cd ../class-notes
• mkdir
• MaKe DIRectory
• Syntax mkdir ltdirectoriesgt
• e.g. mkdir backups
• rmdir
• ReMove DIRectory, which must be empty first
• Syntax rmdir ltdirectoriesgt
• e.g. rmdir backups

10
Files

• Unlike Windows, in Linux file types (e.g.
  executable files, data files, text files)
  are NOT determined by file extension (e.g.
  foo.exe, foo.dat, foo.txt)
• Thus, the file-manipulation commands are few and
  simple. (e.g. hello.c, lecture1_note)
• rm
• ReMoves a file, without a possibility of
  undelete!
• Syntax rm ltfile(s)gt
• e.g. rm tutorial.txt

11
Files (contd)

• cp
• CoPies a file, preserving the original
• Syntax cp ltsourcesgt ltdestinationgt
• e.g. cp tutorial.txt tutorial.txt.bak
• mv
• MoVes or renames a file, destroying the original
• Syntax mv ltsourcesgt ltdestinationgt
• e.g. mv tutorial.txt tutorial.txt.bak

Warning Both of these commands will over-write
existing files without warning you!
12
Shell Shortcuts

• Tab completion
• Type part of a file/directory name, hit lttabgt,
  and the shell will finish as much of the name as
  it can
• Works if youre running bash or tcsh
• Command history
• Dont re-type previous commands use the
  up-arrow to access them
• Wildcards
• Special character(s) which can be expanded to
  match other file/directory names
• Zero or more characters
• ? Zero or one character
• e.g. ls .txt

13
Editing Text

• Which text editor is the best ? Pick one and
  get comfortable with it.
• Three text editors you should be aware of
• pico Easy! Comes with pine (a email program)
• vim/vi A light editor, also used in programming
• emacs A heavily-featured editor commonly used
  in programming

14
Programs and Compilation

• To compile a program
• cc ltoptionsgt ltsource filesgt OR gcc ltoptionsgt
  ltsource filesgt
• -Wall show all warnings
• Whats an executable?
• In Windows, double-clicking on an icon runs a
  program
• In Linux, you can run your executable from the
  command line!
• Type the executable name at the prompt, just like
  a command. In fact, commands are actually
  executables
• However, you may need to specify the path to your
  executables
• ./ltprogramgt runs ltprogramgt in the current
  directory
• e.g.
• frank cc -Wall single_main.c o single_main
• frank ./ single_main

15
Whats Next ?

• Read Lab manual
• Preface to the student
• Part 1 section 1 and 2
• Introduction to Linux A Hands on Guide
• http//www.tldp.org/LDP/intro-linux/html/index.ht
  ml
• chapter 1 and 2
• practice, practice, practice
• Find a textbook or tutorial to learn C, and
  compiling C Programs on Linux
• http//users.actcom.co.il/choo/lupg/tutorials/c-o
  n-unix/c-on-unix.html
• Emacs Tutorial
• http//www.aims.ac.za/resources/tutorials/emacs/s
  tarted.php