1. Tools of Web Development 1: Module C: Using Unix

2. Goals Understand the roles of an operating system.
Understand the difference between command-line and GUI.
Understand some basic Unix commands.

3. What is an Operating System?
It is software.
Controls the relationship between all applications and hardware.
Controls the relationship among applications.

4. Command Line Operating Systems
Use letters with symbols, such as C:\>.
Instructions must be typed.
High rate of error – typos!
Some examples of command line operating systems include DOS and Unix.

5. GUI Operating Systems GUI - Graphic User Interface
Include pictures with descriptive words (icons)
Much easier to move the pointer with the mouse and click on a picture, than to remember commands.
Examples of GUI operating systems include Windows and MAC OS.

6. So, What Does an OS Do?
Controls the INPUT, OUTPUT, and PROCESSING activities for the computer
High-quality O/S can make your computer more effective and efficient
A good OS makes the computer easier to use.

7. The Roles of an OS A Traffic Cop A Communication System A Box of Tools
A Self-Starter

8. A Traffic Cop
Controls the resources of the computer, including memory, file storage, and CPU.
Multitasking (the ability for more than one application to “run” at once) is possible on new computers.

9. A Communications System
Helps all of the hardware components communicate with each other.
Helps applications communicate with the hardware.
Helps applications communicate with one another.

10. A Toolbox
Several utility programs are included with an O/S including File Management, Memory Management, and Networking Tools.

11. A Self-Starter The OS takes over just after booting.
Checks to see all hardware is present.
“Hard Boot” – turning off the computer and then back on
“Soft Boot” – restarting the computer without turning it off first.

12. Unix Developed by Bell Labs in 1969 Command-Line OS
Offered File Sharing
Offered Process-Sharing

13. Introducing Unix Commands
Issue commands from a command prompt: phoenix{jstudent}/:
Unix is case sensitive!
Commands are typed in lowercase: cp (copy) is NOT the same as Cp or CP

14. Unix Shells
Unix has a number of shells which help the user interact with the Operating System Kernel (the main program that stays resident in memory and executes OS commands).
Some shells include the Bourne shell, Korn, Bash, TCSH and Csh (“C-schell”, used on the CS Phoenix Server).

15. Command Syntax Case sensitive! All commands are lowercase
General Format: command [switches] arg1 arg2
Switch
Command
Arguments

16. Command Example
Example: ls –l *.html
Switch
Command
Argument

17. Correcting Typographical Errors
DEL key removes the character to the left (in some Telnet clients, BACKSPACE will also do this)
To erase:
C-w – Erases previous word
C-u – Erases an entire line

18. Directory Structures Unix paths begin with a forward slash
The initial forward slash (/) represents the root directory
Typically, only the system administer has full privileges to the root directory

19. Directory Paths
An absolute path begins at the root: /home/jstudent/public_html/
A relative path indicates location relative to your present working directory: ../images/

20. More on Directories
The command pwd will return the directory name in which you are currently working
The directory that represents your personal section of the server is called your home directory

21. Directory Notation / - represents a directory
/. – represents the current directory
/.. – represents the parent directory
/~ - represents a user’s home directory

22. Creating Directories Don’t use spaces in directory names.
Use _ (underscore character) or camelCasing to name directories.
Directory names are case sensitive (usually in lowercase, with camel casing).

23. Creating a Directory Use the mkdir command: mkdir campingImages
Name of the directory
Command

24. File & Directory Permissions
ls –l command will show full details, including file name, owner name, modification date, size and permission sequence.

25. d rwx r-x r-x Unix Permissions
Permission sequence found at the beginning of a directory listing (first 10 characters):
d rwx r-x r-x
Owner’s Permissions
Group’s Permissions
World’s Permissions
Directory?

26. d rwx r-x r-x Unix Permissions
The first character represents whether the listing is a directory. If it is a directory, a “d” will appear in the first character; otherwise, you should normally see a dash (-).
d rwx r-x r-x

27. Unix Permissions
The remaining nine characters are divided into three triplets.
The first triplet represents the owner’s permissions.
The second is the group’s permissions.
The third triplet represents the World’s permissions.

28. Read Permission
1st position in a triplet: r stands for Read; grants permission to view the contents of a file or directory (Value is ‘r’ or ‘-’).

29. Write Permission
2nd position in a triplet: w stands for Write; grants permission to modify a file or the contents of a directory (Value is ‘w’ or ‘-’).

30. Execute Permission
3rd position in a triplet: x stands for eXecute; grants permission to run an application or open a directory (Value is ‘x’ or ‘-’).

31. Unix Permissions
When changing permissions, we must first decide what number will represent the permissions for a triplet.
We can do this by determining whether or not a permission is turned on or off.
If turned on, a permission gets a value of 1; if turned off, it gets a value of 0.

32. Unix Permissions
After deciding whether the three permissions in a triplet are on or off, we will have a binary number
We can convert the binary number to its octal equivalent

33. Unix Permissions Permissions Binary Octal - - - 0 0 0 - - x 0 0 1 1
- - x
0 0 1 1
- w -
0 1 0 2
- w x
0 1 1 3

34. Unix Permissions Permissions Binary Octal r - - 1 0 0 4 r – x 1 0 1 5
r w -
1 1 0 6
r w x
1 1 1 7

35. The chmod Command
Once you’ve established the octal number representing the permission for each triplet, you can then use the change mode (chmod) command to give a directory or file proper permissions

36. chmod Syntax & Example Syntax: chmod permissionMask file/dir
Example: chmod 755 public_html
Typically, directories and executable files are given “755” permissions, while other files are given “644” permissions

37. Navigating Unix
To move from directory to directory, we use the cd command
Syntax: cd path/

38. Navigating Unix
To move from a child to a parent directory: cd ..

39. Navigating Unix
To move from a grandchild to a parent directory: cd ../..

40. Navigating Unix
To move from one child to a sibling directory: cd ../child2

41. The List Command
The list command (ls) shows the contents of a directory
We can add switches to the list command to modify what the command can do
To use more than one switch, concatenate them: ls -lt

42. List Command Switches
ls –l shows files in long format, including permissions
ls –a shows hidden files
ls –c shows file listings in a column format
ls –t sorts file listings by last modified date

43. Using Wildcards with ls
ls a* Wildcard, All files starting with 'a'
ls *a* All filenames with 'a' in them
ls *a*html All filenames with 'a' in them and ending with html
ls ????? - All 5 character filenames

44. Using Wildcards with ls
ls [abc]* - All filenames starting with a, b, or c
ls [a-c]* - Same as above but done as a range
ls [^a-c]* - All filenames not starting with a, b, or c

45. The Unix Copy Command
cp can be used to make a copy of a file, leaving the original file untouched
Syntax: cp oldfile [path/]newfile

46. The Unix Copy Command
To make a copy of a file while both the original and copy are in the same directory: cp index.html home.html

47. The Unix Copy Command
To make a copy of a file that results in the copy retaining the original’s name, but is housed in a different directory: cp index.html ../academic/

48. The Unix Copy Command
To make a copy of a file that results in the copy having a new name and is housed in a different directory: cp index.html ../academic/home.html

49. The Unix Move Command The mv command has two purposes:
To move files from one directory to another
To rename files
Syntax: mv oldfile newpath/[newfilename]

50. The Unix Move Command
To move a file from one directory to another: mv index.html ../friends/

51. The Unix Move Command
To rename a file (stays in the same directory): mv index.html home.html

52. The Unix Move Command
To move a file and rename it at the same time: mv index.html ../friends/home.html

53. Deleting Files
Use rm to delete files
Syntax: rm filename

54. Deleting Files
To delete a single file: rm index.html (answer Y to confirm delete)
To delete multiple files using a wildcard: rm *.html (answer Y to confirm delete for each file)

55. Deleting Directories Use rmdir to delete directories
DIRECTORY MUST BE EMPTY!!!!
Syntax: rmdir directoryname
To delete a directory: rmdir images/ (answer Y to confirm delete)

56. Other Useful Commands
passwd – Password utility that allows users to update their passwords
exit – End your Unix session (you can also use bye on Phoenix)

57. Other Useful Commands
clear – Gives you a blank screen (you can also use cls on Phoenix)
who – Lists users currently logged in to the server

58. Other Useful Commands
finger username – Retrieves information about a user
cal – Displays a calendar of the current month
date – Displays the current system date

59. Other Useful Commands
!! – (pronounced “bang bang”) repeats the last command
![a..z] – Repeats the last command beginning with selected letter (a-z)

60. Other Useful Commands
|more – Added to commands which display lists to force page stops (Ex: ls –lt |more)
C-z – Temporarily stop a process

61. Other Useful Commands
fg – Bring a process to the foreground after it has been stopped
vacation – Turn on the autoreply for
pine – Launch the Pine client
emacs – Start the Emacs editor

62. Online Manual Eight Sections Commands System calls File formats
Library functions
Devices and device drivers
File formats
Games
Miscellaneous
System maintenance

63. Using man man command To lookup help on the cp command: man cp
To lookup help on the ls command: man ls
C-c exits the manual.

64. Questions?