INLS461 UNIX

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INLS461UNIX

• Scott Adams

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Objectives

• By the end of this week you should be able to
• Describe the underlying structure of UNIX
• Recognize the typical UNIX structure
• Log into UNIX
• Navigate, create and remove directories (cd,
  mkdir , rmdir)
• Move and delete a file (mv, rm)
• Use the UNIX commands to see parts of a file
  (cat, more, head, and tail)

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UNIX vs PC

• UNIX is the first choice for
• High end storage and processing such as
  scientific computing
• Hosting websites
• PC is the first choice for
• Desktop publishing
• Low end processing power
• Command line interfaces
• Typically a high learning curve and low retention
• Post learning faster because your hands dont
  leave the keyboard

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UNIX

• UNIX
• an operating system
• Designed at ATT's Bell Laboratories
• Introduced in 1969
• Linux (Linus Unix)
• an open source variant of UNIX
• 1991, a student named Linus Torwalds from Finland

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History
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ShellHistory
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UNIX Underlying Structure

• UNIX operating system consist of 3 main parts
• Kernel (system)
• Shell (interface)
• Program (applications)
• UNIX uses a command line interface
• All commands in UNIX are CASE SENSITIVE
• spaces matter
• Most commands are one word with optional
  modifying flags or arguments ie command -option
  argument
• Directory file names up to 256 characters long
• UNIX is a hierarchy of directories, structured as
  an inverted tree.

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Accessing UNIX via Telnet

• Via Secure Shell, telnet, or command prompt.
• Enter host name (isis.unc.edu), login (onyen)
  password. Hit connect for prompt

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Accessing UNIX via FTP
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Session Properties
isis.unc.edu
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Transfer
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Class exercise

• Create a file on your PC called Test1.txt
• Save onto the desktop
• Login into your isis via telnet
• Transfer Test1.txt to the public_html folder
• You can see the file by typing cat Test1.txt
• Rename the file to Test2.txt and change the text
• Transfer the file using WS_FTP

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Basic Navigation

• Use ls to LIST files within a directory.
• Use cd to CHANGE DIRECTORY or move among
  subdirectories.
• Verify current location with pwd.

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CD (Change Directory)

• cd .. moves you up one directory level.
• cd ../.. moves you up two directory levels.
• cd SubdirectoryName moves you to the specified
  directory. E.g. cd public_html
• cd alone returns you to your Home directory.

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Simplest ls command, all files on current
directory in columns. Can use wild card ls l
to list only files starting with a certain letter.
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Intermediate ls l includes file permissions,
size, date created
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Fullest ls al includes hidden files
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pwd (print working directory) displays current
directory path
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Modifying Directories

• mkdir creates a new directory
• mkdir SubdirectoryName creates a directory within
  the current directory.
• rm FileName removes the specified file
• rmdir removes an empty directory
• rm r deletes a directory and all files.

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Warning UNIX Can Be Deceptively Powerful

• Remove directory executed at the root can wipe
  out ones entire system. The web abounds with
  UNIX horror stories http//www.zorg.org/unixhumou
  r/unix.admin.horror..html

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Copying Renaming Files

• cp command copies a file or directory.
• mv command moves or renames a file or directory.
• rm command deletes a file or directory.

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For Help, Use man (manual) command
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Creating Text Files

• Type cat gtFileName
• hit enter
• enter text
• save with control-D

• Type Echo text gt filename.txt

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Finding parts of files

• To see the entire file use the cat command
• Cat ltfilenamegt
• Try cat myfiles.txt
• If the text goes too fast pipe to more
• Eg cat ltfilenamegt more
• (more on piping next week)
• To see the first (last) 10 lines use head (tail)
• Eg head ltfilenamegt

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Summary Basic Commands

• display the current directory type pwd (print
  working directory)
• cd (change directory)
• display the directory list ls (ls -l or ls -a or
  ls -al)
• copy cp
• Move mv
• Delete rm
• Rename mv
• mkdir (make directory)
• rmdir (remove directory)
• Cat, more, head, tail
• Man (help command)

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Class Exercise

• Log into UNIX using telnet
• Repeat the steps required to create a file that
  contains your directory structure
• Explore the typical unix file structure that we
  discussed last week

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Acknowledgements

• All slides used in this class have been modified
  from previous versions of INLS102
• UNIX Images from Sarwar, Koretsky, and Sarwar
  UNIX The Textbook 2nd Edition (2005) Pearson
  Addison-Wesley