Download UNIX Software Tools

1 Introducing UNIX
•What is UNIX ?
•UNIX Kernel
•UNIX Shell
•Example Commands
•UNIX Filestore - next lecture
What is UNIX?
UNIX is an operating system
An operating system is the program
that controls all the resources of a
computer system - both the hardware
and the software
Most importantly, it allows you to make
use of the facilities provided by the
system. Every computer has an
operating system.
Different Flavours of UNIX
Commercial: Sun Solaris, SCO, IRIX
Open source: Linux, FreeBSD, NetBSD
 Lots distributions
Cygwin
 Not a full OS but an implementation of all
the standard tools and system calls of UNIX
MacOS X
 Underlying operating system is BSD
Parts of the UNIX System
Hardware
Kernel
Shell or GUI
Tools
&
Apps
UNIX Kernel
At the core of each UNIX system (and
most operating systems)
Loaded in whenever the system is
started up
Manages the entire resources of the
system, presenting them to you and
every other user as a coherent system
You do not need to know about it in
order to use a UNIX system, but very
important if you are administering one.
UNIX Kernel (2)
Amongst the functions performed by
the kernel are:
 managing the machine's memory and
allocating it to each process.
 scheduling the work done by the CPU so
that the work of each user is carried out as
efficiently as possible.
 organising the transfer of data from one
part of the machine to another.
 enforcing the access permissions that are
set on the file system
UNIX Shell
The UNIX command line interface
is called the ‘shell’
The shell is a program interpreter
There are many different shells,
for example csh, bash, sh.
Usually you will run only one type
of shell in a login session
What is a Command Line
Interface?
In Windows you usually do
things by selecting something
with the mouse and then clicking
(GUI), but there is limited
command line support
In UNIX, traditionally, you do
things by typing in commands,
but GUIs are common nowadays.
The Diving Bell and the Butterfly
Command Line Completion
Very useful although not always
available (available in bash!)
Start typing command (or file name)
and then press tab
The shell will try to automatically finish
the word for you
 If more than one choice, press tab again
and the shell will list the possibilities
Copying and Pasting
In Windows you cut and paste
using items in the Edit menu
In UNIX you can also use your
mouse
 Left button (click and drag) to
highlight the text you want to copy
 Middle button (click) to paste the text
somewhere else
A Shell Window
Accessing your Linux account
 Use NoMachine
 For more info, read document by Paul
Dempster (see U drive)
 It’s a client-server system, with a twist
X-Windows
 In a normal client-server system (for example,
an email system) the software on the local
host is the client and the software on the
remote host is the server.
 In a X-Windows system this is reversed.
 The X-Windows server is on your local
machine. It provides the following services:
keyboard input, mouse, procedures for
drawing on the screen, etc.
 The clients are on the remote host. Client
processes running on the remote machine use
your X Server to get the input from your
keyboard and mouse and to display their
output on your screen.
Opening and closing the
terminal
To open
the terminal:
You can close it by typing exit or
pressing ^D (Ctrl+D)
Shell vs. GUI
Advantages of command line interfaces vs
graphical interfaces:
 Easy to automate
 History of commands
 More productive (once you know what you are
doing)
 Works well over slow network connections
Disadvantages:
 More difficult at first (but you get used to it)
Linux at Home
The University’s Linux server is only
accessible from within the campus
You might want to try installing Linux on
your own PC, but this might not be trivial
A simpler option is to download a “live”
distribution (a bootable CD)
UNIX Commands
Shells perform user requests and they do
this by accepting commands
Different types of shell have different
commands, although the core commands are
common
A command consists of one or more words
separated by white space
The first word is the command name
Subsequent words (flags and arguments)
give additional information or modify the
command
 E.g. ls –l /usr
Command Entry
A command is only entered when you
press the ENTER (or RETURN) key
Special key strokes include:
 DELETE or back space to delete the
last character (also ^H)
 ^D to delete the next character
 ^W to delete the last word
 Alt+U to delete the entire line
 ^C to kill most commands
 ^A and ^E to go to the beginning or
end of the line
(^X means press the Control key and X at the
same time)
Example UNIX Commands
who
date
finger
passwd
Example UNIX commands (2)
 The who command displays a list of current users
on the system
 Information includes usernames, where they are
logged in from and when they logged on
zlizmj
zuczpd
zlizmj
zliybzd
zliybzh4
zliychj2
zliyblj5
zlizjc
zuczpd
pts/7
pts/8
pts/9
pts/10
pts/12
pts/13
pts/19
pts/22
pts/15
Mar 5 10:49
Mar 5 11:20
Mar 5 11:20
Jan 2 09:03
Jan 8 12:32
Jan 7 13:50
Jan 26 15:46
Jan 3 14:45 (unix:1031.0)
Jan 3 12:06 (mb-gx520-030.nottingham.edu.cn)
Example UNIX commands (3)
 The date command displays the current date and
time:
Mon Oct
9 11:27:07 BST 2000
 finger describes the person behind a username,
for example,
finger gmh@marian gives:
Login name: gmh
In real life: Graham M Hutton
Directory: /staff/gmh
Shell: /bin/csh
Last login Thu Sep 16, 1999 on pts/2 from marian
No unread mail
Plan:
Example UNIX Commands Changing your password
The passwd command changes your
password
This is one of the first things that you
should do
You are prompted for the old and new
passwords (the new one twice)
You cannot change your password from
the CS Linux server (passwords are
stored on a Windows server)
Other Useful UNIX
Commands
man - manual pages
info - more extensive documentation
gpdf - viewer for PDF files
ggv - viewer for postscript files
konqueror - web browser and shared
folders browser
bzip2 - compress a file (reverse bunzip2)
Summary
Introduction to UNIX
UNIX Kernel
UNIX Shell
Basic UNIX commands
Next Lecture: UNIX Filestore