What is Unix

1
What is Unix?

• A multi-user networked operating system
• Operating System
• Handles files, running other programs,
  input/output
• Looks like DOSbut more powerful
• The internet was designed on it, thus networking
  is an intrinsic part of the system
• Multi-user
• Every user has different settings and permissions
• Multiple users can be logged in simultaneously

2
Unix vs. Linux

• Age
• Unix born in 1970 at ATT/Bell Labs
• Linux born in 1992 in Helsinki, Finland
• Sun, IBM, HP are the 3 largest vendors of Unix
• These Unix flavors all run on custom hardware
• Linux is FREE!
• Linux was written for Intel/x86, but runs on many
  platforms

3
IWS (Instructional Work Servers)

• Accessing the servers
• Terminal Programs
• ssh (via the TeraTerm or Putty programs)
• Start -gt Program Files -gt Desktop Tools -gt
  TeraTerm
• File Transfer Programs
• On CCSE lab Windows machines
• Start -gt Run
• telnet ltserver namegt
• Secure FTP (
• The X Window System

4
Logging In

• Although your Windows and Unix usernames are the
  same, they have separate accounts (different
  passwords)
• Your z drive is not your Unix account
• Connecting
• Well connect to the Unix machines via telnet
• After connection, you are presented with a login
  prompt
• After logging in, youre placed in your home
  directory (where your personal files are located)

5
The Command Prompt

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

prompt ltcommandgt ltflagsgt ltargsgt
CCSE.LINUX ls l -a unix-tutorial
Command
(Optional) arguments
Command Prompt
(Optional) flags
Note Many Unix commands will print a message
only if something went wrong. Be careful with rm
and mv.
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

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

• In Unix, files are grouped together in other
  files called directories, which are analogous to
  folders in Windows
• Directory paths are separated by a forward slash
  /
• Example /homes/iws/robh/classes/cse326
• The hierarchical structure of directories (the
  directory tree) begins at a special directory
  called the root, or /
• Absolute paths start at /
• Example /homes/iws/robh/classes/cse326
• Relative paths start in the current directory
• Example classes/cse326 (if youre currently in
  /homes/iws/robh)
• Your home directory is where your personal
  files are located, and where you start when you
  log in.
• Example /homes/iws/robh

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
• Example ls backups/
• pwd
• Print Working Directory

9
Directories (contd further)

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

10
Files

• Unlike Windows, in Unix 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
• Many use only 2 letters
• rm
• ReMoves a file, without a possibility of
  undelete!
• Syntax rm ltfile(s)gt
• Example rm tutorial.txt backups/old.txt

11
Files (contd)

• cp
• CoPies a file, preserving the original
• Syntax cp ltsourcesgt ltdestinationgt
• Example cp tutorial.txt tutorial.txt.bak
• mv
• MoVes or renames a file, destroying the original
• Syntax mv ltsourcesgt ltdestinationgt
• Examples
• mv tutorial.txt tutorial.txt.bak
• mv tutorial.txt tutorial-slides.ppt backups/

Note 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 tcsh or bash
• 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
• Examples
• ls .txt
• rm may-?-notes.txt

13
Editing Text

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

14
Programs and Compilation

• To compile a program
• g ltoptionsgt ltsource filesgt
• Recommended g -Wall ansi o ltexecutable_namegt
  .cpp
• -Wall show all warnings
• -ansi Strict ANSI compliance
• Whats an executable?
• In Windows, double-clicking on an icon runs a
  program
• E.g. double-click on C\Windows\notepad.exe
• In Unix, 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
• Example
• ceylonehsu g -Wall ansi o hello hello.cpp
• ceylonehsu ./hello