1. The Essence of UNIX and Linux
Chapter One
The Essence of UNIX and Linux
Guide To UNIX Using Linux Fourth Edition
Chapter 1 Unix (42 slides) 1

2. Objectives
Explain operating systems, including PC, mainframe, and network operating systems
Describe the UNIX and Linux operating systems
Explain the purpose of UNIX/Linux shells
Understand how to select user names and passwords
Connect to UNIX/Linux using Telnet or SSH
Chapter 1 Unix (42 slides)
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3. Objectives (continued)
Use basic UNIX/Linux commands and command- line editing features
Explain the role of a system administrator
Change your password for security
Use multiple commands to view the contents of files
Redirect output to a file
Chapter 1 Unix (42 slides)
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4. Understanding Operating Systems
Operating System (OS)
The most fundamental computer program
Enables you to store information, process raw data, use application software, compile your own programs, and access attached hardware, such as a printer or keyboard
Chapter 1 Unix (42 slides)
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5. Understanding Operating Systems
Chapter 1 Unix (42 slides)
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6. PC Operating Systems
A personal computer (PC) OS conducts all I/O, processing, and storage operations on a stand-alone computer
Chapter 1 Unix (42 slides)
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7. Mainframe Operating Systems
A mainframe OS controls a large computer system with multiple processors for I/O, processing, and storage operations for many users
Chapter 1 Unix (42 slides)
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8. Network Operating Systems
A network OS controls the operations of a server computer (host), which accepts requests from user programs running on other computers (clients)
Chapter 1 Unix (42 slides)
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9. Server-based vs. peer-to-peer networks
Server-based network
Centralized processing approach
Data and applications server resident
If server fails, entire network fails
Peer-to-peer
Distributed processing approach
Data and applications workstation resident
Each system is both a server and a client
Chapter 1 Unix (42 slides)
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10. Introducing the UNIX and Linux Operating Systems
UNIX/Linux can be used on systems functioning as:
Dedicated servers or client workstations in a server-based network
Client/server workstations connected to a peer-to-peer network
Stand-alone workstations not connected to a network
Chapter 1 Unix (42 slides)
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11. Introducing the UNIX and Linux Operating Systems (continued)
UNIX/Linux is a multi-user system
UNIX/Linux is a multitasking system
Can execute more than one program at a time
UNIX/Linux is a portable operating system
Used in many computing environments
Chapter 1 Unix (42 slides)
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12. A Brief History of UNIX
Bell Labs originally developed UNIX in the late 1960s and early 1970s
Distributed in source code form
Universities modified the code to work on different machines
Two standard versions of UNIX evolved
System V (Bell Labs)
Berkeley Software Distribution (BSD)
Chapter 1 Unix (42 slides)
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13. UNIX Concepts The interface between user and OS
Shell
The interface between user and OS
Hierarchical Structure
Directory and subdirectory organization
Layered components
Layers of software surround the computer’s inner core
Chapter 1 Unix (42 slides)
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14. Chapter 1 Unix (42 slides)
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15. Linux and UNIX Linux is UNIX-like
Not written from traditional UNIX code
Linux is original code
Includes POSIX standards
Other Linux information
Created by Linus Torvalds
Offers all the complexity of UNIX
Linux can coexist with other OSs
Chapter 1 Unix (42 slides)
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16. Introducing UNIX/Linux Shells
A shell is a UNIX/Linux program that interprets the commands you enter from the keyboard
Chapter 1 Unix (42 slides)
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17. Choosing Your Shell
Shells interpret commands and act as first-class programming languages
A default shell is associated with your account when created; Bash is the default shell in Linux
Some UNIX/Linux shells: Bourne, Korn, C shell, Bash
Can switch from shell to shell
Chapter 1 Unix (42 slides)
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18. Choosing User Names and Passwords
To use UNIX/Linux, a user must log in by providing a unique user name and password
UNIX/Linux system administrators create accounts by adding user names and passwords
Users log in to UNIX or Linux systems as long as they have accounts on the workstation or host (server) computer
Chapter 1 Unix (42 slides)
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19. Connecting to UNIX/Linux Using Telnet or SSH
Remotely through Telnet (Use SSH Mostly Now!)
Through network client software
As peer on peer-to-peer network
On a stand-alone PC
Through a dumb terminal
Chapter 1 Unix (42 slides)
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20. Connecting to UNIX Using Telnet
Telnet is terminal emulation software
Connects your PC to a server, or host
PC could be running UNIX, Linux, Windows OS, or Macintosh OS
Once connected to a UNIX/Linux host, work with UNIX/Linux may begin
Uses IP addresses or domain names to access remote systems
Chapter 1 Unix (42 slides)
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21. Secure Shell (SSH)
Developed for UNIX/Linux systems to provide authentication security for TCP/IP applications, such as FTP and Telnet
Can encrypt communications as they go across a network or the Internet
openSSH includes protocols and software for free distribution on UNIX/Linux systems
Chapter 1 Unix (42 slides)
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22. Logging In to UNIX/Linux
Log in by entering username and password when UNIX/Linux system booted or connected to
Enter at prompt (command-line mode) or into login box (GUI mode)
Now commands can be issued at the command prompt
Chapter 1 Unix (42 slides)
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23. Logging In to UNIX/Linux (continued)
With a standalone computer and an X Window desktop such as GNOME, you must open a terminal window to access the command prompt
Chapter 1 Unix (42 slides)
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24. Using Commands
To interact with UNIX/Linux, a command is entered at the command prompt
UNIX/Linux is case-sensitive and most commands are typed in lower case
Two categories of commands
User-level: perform tasks
System administration: system management
Chapter 1 Unix (42 slides)
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25. Using Commands (continued)
The date command
Displays the system date, which the system administrator maintains
The cal command
Shows the system calendar
Chapter 1 Unix (42 slides)
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26. Using Commands (continued)
Chapter 1 Unix (42 slides)
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27. Using Commands (continued)
Chapter 1 Unix (42 slides)
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28. Using Commands (continued)
The who Command
To get information about who is logged in
Useful for administrators and users
The clear Command
Clears the screen
The whatis command
Displays a brief description of a command for help purposes
Chapter 1 Unix (42 slides)
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29. Using Commands (continued)
The man program displays the UNIX/Linux online reference manual, called the man pages, for help purposes
Chapter 1 Unix (42 slides)
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30. Using Commands (continued)
Command-line editing
Certain keystrokes perform command-line editing (shell dependent)
Multiple command entries
More than one command on one line by separating with a semicolon(;)
Chapter 1 Unix (42 slides)
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31. Using Commands (continued)
Command-line history
Use up and down arrow keys to scroll through command history
Logging out ends your current process and indicates to UNIX that you are finished
Logging out is shell dependent
Bourne, Korn, Bash – exit command
C shell – logout command
Chapter 1 Unix (42 slides)
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32. Understanding the Role of the UNIX/Linux System Administrator
System administrator manages the UNIX/Linux system
Adds users and deletes old accounts
Also called the superuser
Unlimited permission to alter system
Unique user name: root
Prompt ends with # (pound) symbol
Chapter 1 Unix (42 slides)
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33. Understanding the Role of the UNIX/Linux System Administrator (continued)
The System Administrator’s Command Line
root]#
The Ordinary User’s Command Line
username] $
Chapter 1 Unix (42 slides)
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34. Changing Passwords
For security purposes, changing passwords is necessary
Use the passwd command
UNIX/Linux allows new password if:
The new password differs by at least three characters
It has six or more characters, including at least two letters and one number
It is different from the user name
Chapter 1 Unix (42 slides)
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35. Viewing Files Using the cat, more, less, head, and tail Commands
Use cat, more, and less to view an entire file contents
cat displays a whole file at one time
more displays a file one screen at a time, allowing scroll down
less displays a file one screen at a time, allowing scroll down and up
Chapter 1 Unix (42 slides)
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36. Viewing Files Using the cat, more, less, head, and tail Commands (continued)
Use head and tail to view the first few or last few lines of a file
head displays the first few lines (10 lines)
tail displays the last few lines (10 lines)
Chapter 1 Unix (42 slides)
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37. Redirecting Output
The greater than sign (>) is called a redirection symbol
Create a new file or overwrite an existing file by attaching (>) to a command that produces output
To append to an existing file, use two redirection symbols (>>)
Chapter 1 Unix (42 slides)
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38. Chapter Summary
OS controls all computer resources and provides the base upon which application programs can be used or written
A server-based network is centralized (handled by the system administrator)
A peer-to-peer network is decentralized
UNIX/Linux are multi-user, multitasking
Chapter 1 Unix (42 slides)
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39. Chapter Summary (continued)
UNIX/Linux systems can be configured as servers, client workstations, client/server workstations, or stand-alone
The concept of the layered components that make up an OS originated with UNIX
Linux is a UNIX-like OS for a PC
You communicate with the OS programs through an interpreter called the shell
Chapter 1 Unix (42 slides)
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40. Chapter Summary (continued)
The system administrator sets up accounts for users that supply a username and password
You work with UNIX by typing commands that you can learn by referring to the online manual called man pages
Chapter 1 Unix (42 slides)
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41. Chapter Summary (continued)
Most shells provide basic command-line editing capabilities and keep a history of your most recently used commands
You can view the contents of files with view commands such as cat, less, more, head, and tails
Chapter 1 Unix (42 slides)
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42. Chapter 1 Unix Exercises
Work through Hands-on Projects at end of chapter 1
Canvas: Review Questions 1
(Do not do questions 22,23,24
and 25 on All Unix Chapters!)
Read chapter 2 before next class session
Quiz 1 UNIX…
Chapter 1 Unix (42 slides)
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43. Exploring the UNIX/Linux File Systems and File Security
Chapter Two
Exploring the UNIX/Linux File Systems and File Security
Guide To UNIX Using Linux Fourth Edition 43
CTEC 110
Chapter 2 Unix (31 slides)

44. Objectives Discuss UNIX/Linux file systems
Explain partitions and inodes
Understand the elements of the root hierarchy
Use the mount command
Explain and use paths, pathnames, and prompts
Navigate the file system
Create and remove directories
Copy and delete files
Configure file permissions 44
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Chapter 2 Unix (31 slides)

45. Understanding UNIX/Linux File Systems
File: basic component for data storage
UNIX/Linux considers everything to be a file
A file system is UNIX/Linux’s way of organizing files on mass storage devices
A physical file system is a section of the hard disk that has been formatted to hold files
The file system is organized in a hierarchical structure (inverted tree) 45
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Chapter 2 Unix (31 slides)

46. Understanding UNIX/Linux File Systems (continued)46
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Chapter 2 Unix (31 slides)

47. Understanding the Standard Tree Structure
The structure starts at the root level
Root is the name of the file at this basic level and it is denoted by the slash character (/)
Directory: file that can contain other files and directories
Subdirectory: directory within a directory
The subdirectory is considered the child of the parent directory 47
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Chapter 2 Unix (31 slides)

48. Using UNIX/Linux Partitions
The section of the disk that holds a file system is called a partition
When installing UNIX/Linux, one of the first tasks is deciding how to partition a storage device, or hard disk
Hard disks may have many partitions
UNIX/Linux partitions are given names
LINUX uses hda1 and hda2 48
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Chapter 2 Unix (31 slides)

49. Using UNIX/Linux Partitions (continued)
Storage devices are called peripheral devices
Peripheral devices connect to the computer through electronic interfaces
IDE: Integrated Drive Electronics
SCSI: Small Computer System Interface 49
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Chapter 2 Unix (31 slides)

50. 50
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51. Setting Up Hard Disk Partitions
Partitioning your hard disk provides organized space for file systems
At least 3 partitions (root, swap, /boot) often recommended
Root partition holds root file system directory (/), size depends on installation but often ranges between 1.2 to 5+ GB 51
CTEC 110
Chapter 2 Unix (31 slides)

52. Setting Up Hard Disk Partitions (continued)
Swap partition acts as a memory extension, often has same size as RAM, enables virtual memory
/boot partition used to store the os files comprising the kernel and is relatively small
Other used partitions include /usr, /home, /var 52
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Chapter 2 Unix (31 slides)

53. Using Inodes
Inodes are associated with directories and files in ufs and ext file systems
An inode contains the name, general information, and location information (a pointer) for a file or directory
A superblock contains information about the block layout on a specific partition 53
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Chapter 2 Unix (31 slides)

54. Exploring the Root Hierarchy
UNIX/Linux must mount a file system before any programs can access files on it
To mount a file system is to connect it to the directory tree structure
The root file system is mounted by the kernel when the system starts 54
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Chapter 2 Unix (31 slides)

55. Exploring the Root Hierarchy (continued)
The root directory contains sub-directories that contain files:
/bin contains binaries, or executables needed to start the system and perform system tasks
/boot contains files needed by the bootstrap loader as well as kernel images
/dev contains system device reference files 55
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Chapter 2 Unix (31 slides)

56. 56
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57. Exploring the Root Hierarchy (continued)
Root subdirectories continued:
/etc contains configuration files that the system uses when the computer starts
/lib contains kernel modules, security information, and the shared library images
/mnt contains mount points for temporary mounts by the system administrator
/proc is a virtual file system allocated in memory only 57
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Chapter 2 Unix (31 slides)

58. Exploring the Root Hierarchy (continued)
Root subdirectories continued:
/root is the home directory of the root user, or the system administrator
/sbin contains essential network programs used only by the system administrator
/tmp is a temporary place to store data during processing cycles
/var contains subdirectories which have sizes that often change, such as error logs 58
CTEC 110
Chapter 2 Unix (31 slides)

59. Using the mount Command
Users can access mounted file systems which they have permission to access
Additional file systems can be mounted at any time using the mount command
To ensure system security, only the root user uses the mount command 59
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Chapter 2 Unix (31 slides)

60. Using Paths, Pathnames, and Prompts
To specify a file or directory, use its pathname, which follows the branches of the file system to the desired file
A forward slash (/) separates each directory name
The UNIX/Linux command prompt may indicate your location within the file system
Use the UNIX/Linux pwd command to display the current path name 60
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Chapter 2 Unix (31 slides)

61. 61
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62. 62
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63. Navigating the File System
To navigate the UNIX/Linux directory structure, use the cd (change directory) command
UNIX/Linux refers to a path as either:
Absolute - begins at the root level and lists all subdirectories to the destination file
Relative - begins at your current working directory and proceeds from there 63
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Chapter 2 Unix (31 slides)

64. Using Dot and Dot Dot Addressing Techniques
UNIX/Linux interpret a single dot (.) to mean the current working directory
Two dots (..) mean the parent directory
cd .. moves you up a level in the directory structure 64
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Chapter 2 Unix (31 slides)

65. Listing Directory Contents
The ls (list) command displays a directory’s contents, including files and subdirectories 65
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Chapter 2 Unix (31 slides)

66. Using Wildcards
A wildcard is a special character that is used as a placeholder
The * wildcard represents any group of characters in a file name
The ? wildcard represents a single character in a file name 66
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Chapter 2 Unix (31 slides)

67. Creating and Removing Directories and Files
mkdir (make directory) command
Create a new directory
rmdir (remove directory) command
Delete an empty directory
cp (copy) command
Copy files from one directory to another
rm (remove) command
Delete files 67
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Chapter 2 Unix (31 slides)

68. Configuring File Permissions for Security68
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Chapter 2 Unix (31 slides)

69. Configuring File Permissions for Security (continued)
Owner has read w
Owner has write x
Owner has execute
Group has read -
Group does not have write
Group has execute
Others have read
Others do not have write
Others have execute 69
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Chapter 2 Unix (31 slides) 69

70. Configuring File Permissions for Security (continued)
chmod command
To set file permissions
Settings are read (r), write (w), execute (x)
The three types of users are owners(users), groups, and others(world) or simply (ugo)
Setting permissions to directories
Use the execute (x) to grant access 70
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Chapter 2 Unix (31 slides)

71. Chapter 2 Unix Exercises
Work through Hands-on Projects at end of chapter 2
Canvas: Review Questions 2
(Do not do questions 22,23,24 and 25)
Read chapter 3 before next class session
Quiz 2 Unix… 73
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Chapter 2 Unix (31 slides)

72. Chapter 3 Mastering Editors
Guide To UNIX Using Linux Fourth Edition 74
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Chapter 3 (40 slides) 74

73. Objectives
Explain the basics of UNIX/Linux files, including ASCII, binary, and executable files
Understand the types of editors
Create and edit files using the vi editor
Create and edit files using the Emacs editor 75
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74. Understanding UNIX/Linux Files
Almost everything you create in UNIX/Linux is stored in a file
Bit: binary digit
In one of two states: 0 or 1
Machine language: exclusive use of 0s and 1s as a way to communicate with computer
Used by earliest programmers 76
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75. ASCII Text Files Byte (binary term): string of eight bits
A byte can be configured into fixed patterns of bits
ASCII: American Standard Code for Information Interchange
256 different characters
Unicode
Supports up to 65,536 characters
Text files: contain nothing but printable characters
Binary files: contain nonprintable characters
Example: machine instructions 77
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76. Look at Page 113 78
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77. Binary Files Some things cannot be represented with ASCII codes
Binary files are used instead
Example: graphic files include bit patterns
Bitmap: made of rows and columns of dots 79
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78. Executable Program Files
Text files containing program code are compiled into machine-readable language
Scripts are files containing commands
Typically interpreted, not compiled
Executables: compiled and interpreted files that can be run 80
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79. Using Editors
Editor: program for creating and modifying files containing source code, text, data, memos, etc.
Text editor: a simplified word-processing program
Used to create and edit documents
Two text editors normally included in UNIX/Linux are screen editors vi
Emacs
Line editor: works with one line (or group of lines) at a time 81
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80. Using the vi Editor vi is a visual editor vi is also a modal editor
Supports three modes
Insert mode
Accessed by typing “i”
Command mode
Accessed by typing Esc
Extended (ex) command set mode
Accessed by typing “:” in command mode
Download the vi editor document on Blackboard for reference 82
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81. Creating a New File in the vi Editor83
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82. Inserting Text When you start vi, you are in command mode
To insert text in your file, switch to insert mode
Use i (insert) command
To return to command mode, press Esc 84
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83. Repeating a Change
Use a period (.) to repeat the most recent change you made
Repeat command
Works in command mode 85
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84. Moving the Cursor
To move cursor use arrow keys (command/insert mode) or (in command mode) use: 86
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85. Deleting Text Deletion commands available (command mode)
dd is used for “cutting” text
Use “yank” (yy) command for “copying” text 87
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86. Undoing a Command Type u to use the undo command Example:
If you delete a few lines from a file by mistake, type u to restore the text 88
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87. Searching for a Pattern
To search forward for a pattern of characters:
Type a forward slash (/)
Type the pattern you are seeking
Press Enter
Examples: /\<top, /s..n, /pas[st], /!$ 89
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88. Searching and Replacing
Screen-oriented commands execute at the location of the cursor
Line-oriented commands require you to specify an exact location (an address) for the operation
Preceded by a colon (:)
Operate in ex mode
Used for commands that perform more than one action
Example: searching and replacing
:1,$s/insure/ensure/g 90
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89. Saving a File and Exiting vi
To save file without exiting, use :w
To save and exit, use :wq, :x, ZZ
(Do this in command mode) 91
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90. Adding Text from Another File
To copy entire contents of one file into another file:
Use vi to edit the file you would like to copy into
Use the command :r filename
filename is the name of the file that contains the information you want to copy 92
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91. Leaving vi Temporarily
To launch a shell or execute other commands from within vi, use :!
Example:
:!cal
To run several command-line commands in a different shell without closing vi session
Use Ctrl+z to display the command line
Type fg to go back to vi 93
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92. Leaving vi Temporarily (continued)
Chapter 3 (40 slides)
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93. Changing Your Display While Editing
To turn on line numbering
:set number
To delete lines 4 through 6 (ex mode)
:4,6d 95
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94. Copying or Cutting and Pasting
The command yy copies (yanks) a specified number of lines
To cut the lines, use dd
Lines are placed in clipboard
Use p to paste the clipboard contents 96
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95. Printing Text Files
To print a file, use the lpr (line print) shell command
Example:
:!lpr -P lp2 accounts 97
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96. Canceling an Editing Session
Canceling an editing session will discard all the changes you have made
Or, save changes you made since last using :w
Saves file without exiting vi 98
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97. Getting Help in vi Use the help command Other alternatives: :help
man vi
From the command line
:!man vi
From vi (command mode) 99
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98. Using the Emacs Editor Emacs is a popular UNIX/Linux text editor
Not modal
More complex than vi
More consistent than vi
Sophisticated macro language
Macro: set of commands that automates a complex task
Uses: read mail, edit contents of directories, etc.
Powerful command syntax
Extensible
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99. Using the Emacs Editor (continued)
Chapter 3 (40 slides)
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100. Using the Emacs Editor (continued)
Chapter 3 (40 slides)
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101. Creating a New File in Emacs
Chapter 3 (40 slides)
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102. Navigating in Emacs To create a new file: emacs filename
To navigate in the file, use the cursor movement keys or Ctrl/Alt key combinations
Example: Alt+f
To save your work:
Use File menu
Use the save icon
Press Ctrl+x, Ctrl+s
To exit: use menu, icon, or Ctrl+x, Ctrl+c
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103. Deleting Information
Del or Backspace keys delete individual characters
Ctrl+k deletes to the end of a line
To undo a deletion, use Ctrl+x, u
Repeatedly undoes each deletion
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104. Copying, Cutting, and Pasting Text
To Copy-Paste or Cut-Paste:
Mark the text
Position cursor at the beginning, and Ctrl+Spacebar
Navigate to the end of the text you want to include:
Alt+w copies the text
Ctrl+w cuts the text
To paste, move to where you want to place the text
Ctrl+y (the yank command)
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105. Searching in Emacs One way to search in Emacs is to:
Press Ctrl+s
Entering string to find (on status line)
Pressing Ctrl+s repeatedly to find each occurrence
Use Ctrl+r to search backward
Other alternatives:
Use search forward for a string icon
On the menu: Edit  Search  Search
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106. Reformatting a File Alt+q turns on word wrap feature
Lines automatically wrap around from one line to the next
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107. Getting Help in Emacs
Emacs comes with extensive documentation and a tutorial
Tutorial is useful for getting up to speed quickly
Click Help menu  Emacs Tutorial
Or (in most versions), type Ctrl+h and then type t
To view general Emacs documentation:
Ctrl+h (press one or two times)
Or, man emacs at command line
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108. Summary
Bytes: computer characters (a series of bits) stored using numeric codes
The vi editor is popular among UNIX/Linux users
Three modes: insert (i), command (Esc), and ex (Esc :)
With vi, you edit a copy of the file placed in memory
File is not altered until you save it on disk
Emacs is a popular alternative to vi
Supports powerful command syntax and is extensible
Insert text simply by typing
Sophisticated macro language
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109. Command Summary
Chapter 3 (40 slides)
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110. Command Summary (continued)
Chapter 3 (40 slides)
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111. Chapter 3 Unix Exercises
Work through Hands-on Projects at end of chapter 3
Canvas: Review Questions
(Do not do questions 22,23,24 and 25)
Read chapter 4 before next class session
Quiz 3 Unix…
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112. UNIX/Linux File Processing
Chapter Four
UNIX/Linux File Processing
Guide To UNIX Using Linux Fourth Edition
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113. Objectives Explain UNIX and Linux file processing
Use basic file manipulation commands to create, delete, copy, and move files and directories
Employ commands to combine, cut, paste, rearrange, and sort information in files
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114. Objectives (continued)
Create a script file
Use the join command to link files using a common field
Use the awk command to create a professional- looking report
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115. UNIX and Linux File Processing
Based on the approach that files should be treated as nothing more than character sequences
Because you can directly access each character, you can perform a range of editing tasks – this offers flexibility in terms of file manipulation
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116. Reviewing UNIX/Linux File Types
Regular files, also known as ordinary files
Create information that you maintain and manipulate, and include ASCII and binary files
Directories
System files for maintaining file system structure
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117. Reviewing UNIX/Linux File Types (continued)
Special files
Character special files relate to serial I/O devices
Block special files relate to devices such as disks
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118. Understanding File Structures
Files can be structured in many ways depending on the kind of data they store
UNIX/Linux store data, such as letters and product records, as flat ASCII files
Three kinds of regular files are
Unstructured ASCII character
Unstructured ASCII records
Unstructured ASCII trees
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119. 121
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120. Processing Files
UNIX/Linux processes commands by receiving input from a standard input device (e.g. keyboard) and sending it to a standard output device (e.g. monitor)
System administrators and programmers refer to standard input as stdin, standard output as stdout
When UNIX/Linux detect errors, they send data to standard error (stderr, the monitor)
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121. Using Input and Error Redirection
You can use redirection operators to retrieve input from something other than the standard input device and send output to something other than the standard output device
Examples of redirection
Redirect the ls command output to a file, instead of to the monitor (or screen)
Redirect a program that receives input from the keyboard to receive input from a file instead
Redirect error messages to files, instead of to the screen by default
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122. Manipulating Files
When you manipulate files, you work with the files themselves, as well as their contents
Create files using output redirection
cat command - concatenate text via output redirection
without a command - > filename
touch command - creates empty files
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123. Manipulating Files (continued)
Delete files when no longer needed
rm command - permanently removes a file or an empty directory
The -r option of the rm command will remove a directory and everything it contains
Copy files as a means of back-up or as a means to assist with new file creation
cp command - copies the file(s) specified by the source path to the location specified by the destination path
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124. Manipulating Files (continued)
Move files from directory to directory
mv command - removes file from one directory and places it in another
Finding a file helps you locate it in the directory structure
find command - searches for the file that has the name you specify
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125. Manipulating Files (continued)
Combining files using output redirection
cat command - concatenate text of two different files via output redirection
paste command - joins text of different files in side by side fashion
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126. The paste command joins text of different files in side by side fashion
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127. Extracting fields of a file using output redirection: the cut command removes specific columns or fields from a file
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128. Manipulating Files (continued)
Sorting the contents of a file
sort command - sorts a file’s contents alphabetically or numerically
the sort command offers many options:
You can sort the contents of a file and redirect the output to another file
Utilizing a sort key provides the option of sorting on a field position within each line
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129. 131
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130. Creating Script Files
UNIX/Linux users create shell script files to contain commands that can be run sequentially as a set – this helps with the issues of command automation and re-use of command actions
UNIX/Linux users use the vi editor to create script files, then make the script executable using the chmod command with the x argument
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131. Chapter 4 (27 Slides)
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132. Using the join Command on Two Files
Sometimes you want to link the information in two files
The join command is often used in relational database processing
The join command associates information in two different files on the basis of a common field or key in those files
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133. A Brief Introduction to the Awk Program
Awk, a pattern-scanning and processing language helps to produce professional-looking reports
Awk provides a powerful programming environment that can perform actions on files that are difficult to duplicate with a combination of other commands
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134. A Brief Introduction to the Awk Program (continued)
Awk checks to see if the input records in specified files satisfy a pattern
If so, awk executes a specified action
If no pattern is provided, awk applies the action to every record
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135. Chapter Summary
UNIX/Linux supports regular files, directories, and character and block special files
File structures depend on data being stored
UNIX/Linux receives input from the standard input device (keyboard, stdin) and sends output to the standard output device (monitor, stdout)
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136. Chapter Summary (continued)
touch updates a file’s time and date stamps and creates empty files
rmdir removes empty directories
cut extracts specific columns or fields from a file
paste combines two or more files
sort sorts a file’s contents
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137. Chapter Summary (continued)
To automate command processing, include commands in a script file
join extracts data from two files sharing a common field and uses this field to join the two files
Awk is a pattern-scanning and processing language useful for creating a formatted report with a professional look
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138. Chapter 4 Unix Exercises
Work through Hands-on Projects at end of chapter 4
Canvas: Review Questions 4
(Do not do questions 22,23,24 and 25)
Read chapter 5 before next class session
Quiz 4 Unix…
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139. Advanced File Processing
Chapter Five
Advanced File Processing
Guide To UNIX Using Linux Fourth Edition
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140. Objectives
Use the pipe operator to redirect the output of one command to another command
Use the grep command to search for a specified pattern in a file
Use the uniq command to remove duplicate lines from a file
Use the comm and diff commands to compare two files
Use the wc command to count words, characters and lines in a file
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141. Objectives (continued)
Use manipulation and transformation commands, which include sed, tr, and pr
Design a new file-processing application by creating, testing, and running shell scripts
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142. Advancing Your File-Processing Skills
Selection commands focus on extracting specific information from files
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143. Advancing Your File-Processing Skills (continued)
Manipulation and transformation commands alter and transform extracted information into useful and appealing formats
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144. Advancing Your File-Processing Skills (continued)
146
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145. Using the Selection Commands
Using the Pipe Operator
– The pipe operator (|) redirects the output of one command to the input of another
An example would be to redirect the output of the ls command to the more command
The pipe operator can connect several commands on the same command line
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146. Using the Pipe Operator
Using pipe operators and connecting commands is useful when viewing directory information
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147. Using the grep Command
Used to search for a specific pattern in a file, such as a word or phrase
grep’s options and wildcard support allow for powerful search operations
You can increase grep’s usefulness by combining with other commands, such as head or tail
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148. Using the uniq Command Removes duplicate lines from a file
Compares only consecutive lines, therefore uniq requires sorted input
uniq has an option that allows you to generate output that contains a copy of each line that has a duplicate
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149. Using the uniq Command (continued)
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150. Using the uniq Command (continued)
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151. Using the comm Command Column one contains lines found only in file1
Used to identify duplicate lines in sorted files
Unlike uniq, it does not remove duplicates, and it works with two files rather than one
It compares lines common to file1 and file2, and produces three column output
Column one contains lines found only in file1
Column two contains lines found only in file2
Column three contains lines found in both files
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152. Using the diff Command
Attempts to determine the minimal changes needed to convert file1 to file2
The output displays the line(s) that differ
Codes in the output indicate that in order for the files to match, specific lines must be added or deleted
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153. Using the wc Command
Used to count the number of lines, words, and bytes or characters in text files
You may specify all three options in one issuance of the command
If you don’t specify any options, you see counts of lines, words, and characters (in that order)
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154. Using the wc Command (continued)
The options for the wc command:
–l for lines
–w for words
–c for characters
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155. Using Manipulation and Transformation Commands
These commands are: sed, tr, pr
Used to edit and transform the appearance of data before it is displayed or printed
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156. Introducing the sed Command
sed is a UNIX/Linux editor that allows you to make global changes to large files
Minimum requirements are an input file and a command that lets sed know what actions to apply to the file
sed commands have two general forms
Specify an editing command on the command line
Specify a script file containing sed commands
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157. Translating Characters Using the tr Command
tr copies data from the standard input to the standard output, substituting or deleting characters specified by options and patterns
The patterns are strings and the strings are sets of characters
A popular use of tr is converting lowercase characters to uppercase
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158. Using the pr Command to Format Your Output
pr prints specified files on the standard output in paginated form
By default, pr formats the specified files into single- column pages of 66 lines
Each page has a five-line header containing the file name, its latest modification date, and current page, and a five-line trailer consisting of blank lines
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159. Designing a New File-Processing Application
The most important phase in developing a new application is the design
The design defines the information an application needs to produce
The design also defines how to organize this information into files, records, and fields, which are called logical structures
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160. Designing Records
The first task is to define the fields in the records and produce a record layout
A record layout identifies each field by name and data type (numeric or nonnumeric)
Design the file record to store only those fields relevant to the record’s primary purpose
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161. Linking Files with Keys
Multiple files are joined by a key: a common field that each of the linked files share
Another important task in the design phase is to plan a way to join the files
The flexibility to gather information from multiple files comprised of simple, short records is the essence of a relational database system
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163. Creating the Programmer and Project Files
With the basic design complete, you now implement your application design
UNIX/Linux file processing predominantly uses flat files
Working with these files is easy, because you can create and manipulate them with text editors like vi and Emacs
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164. Creating the Programmer and Project Files (continued)
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165. Formatting Output Awk provides a shortcut to other UNIX/Linux commands
The awk command is used to prepare formatted output
For the purposes of developing a new file- processing application, we will focus primarily on the printf action of the awk command
Awk provides a shortcut to other UNIX/Linux commands
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166. Using a Shell Script to Implement the Application
Shell scripts should contain:
The commands to execute
Comments to identify and explain the script so that users or programmers other than the author can understand how it works
Use the pound (#) character to mark comments in a script file
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167. Running a Shell Script
You can run a shell script in virtually any shell that you have on your system
The Bash shell accepts more variations in command structures that other shells
Run the script by typing sh followed by the name of the script, or make the script executable and type ./ prior to the script name
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168. Putting it All Together to Produce the Report
An effective way to develop applications is to combine many small scripts in a larger script file
Have the last script added to the larger script print a report indicating script functions and results
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169. Chapter Summary
UNIX/Linux file-processing commands are (1) selection and (2) manipulation and transformation commands
uniq removes duplicate lines from a sorted file
comm compares lines common to file1 and file2
diff tries to determine the minimal set of changes needed to convert file1 into file2
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170. Chapter Summary (continued)
tr copies data read from the standard input to the standard output, substituting or deleting characters specified
sed is a file editor designed to make global changes to large files
pr prints the standard output in pages
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171. Chapter Summary (continued)
The design of a file-processing application reflects what the application needs to produce
Use record layout to identify each field by name and data type
Shell scripts should contain commands to execute programs and comments to identify and explain the programs
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172. Chapter 5 Unix Exercises
Work through Hands-on Projects at end of chapter 5
Canvas: Review Questions 5
(Do not do questions 22,23,24 and 25)
Quiz 5 Unix…
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