Introduction to UNIX

1. Introduction to UNIX A User’s Perspective: Day 1 – The File System

2. Requirements for System Access • Authentication • User account • Password

3. Connecting to the System • Telnet & FTP • Insecure • Clear-Text Transfer of ALL data • Resident on most systems • SSH & SFTP • Secure • Encrypted transfer of ALL data • Free download from ftp://ftp.ssh.com/pub/ssh/ • SSHSecureShellClient-3.2.2.exe

4. Let’s Log On! • Hand out Account Sheets • Logon to the System

5. What You Will See…

6. Now Do It Securely

7. Success!!

8. Maneuvering on the Command-Line • Esc – k • First enter in command history • k to move UP through history • j = Down • l = Left • h = Right • i = Insert • x = Delete • Shift-U = Undo • ESC when in trouble ;)

9. The Windows/UNIX difference • Capable of getting under the hood • Windows – Difficult • The Registry – Nuff said! • UNIX – Manageable • Configuration files • Fundamental knowledge expandable

10. What we will Cover Today • Definition of UNIX (2 slides!) • UNIX File System • Basic Commands • Ownership & Permissions • Shells

11. UNIX What is it? • Multi-user System • File based system • Extensible • Honed for networking • Portable – runs on anything

12. UNIX Distributions • Linux • Redhat, Mandrake, SuSe, etc. • AIX • IBM • Solaris • SUN • HP-UX • HP

13. What Should You Know? • How to Log on and off of a UNIX system • How the process works

14. Question? • Anyone… anyone?

15. Now that you are logged in… • Account Shells • csh – C-Shell • % • ksh – Korn • $ • bsh – Bourne Shell • $ • Bash – Bourne Again Shell • #

16. C-Shell – csh • Interactive command interpreter • Command programming language • Syntax similar to the C programming language • /bin/csh or /usr/bin/csh • Executes • /etc/profile OR /etc/login • $HOME/.login OR $HOME/.cshrc

17. The Korn Shell – ksh • Interactive command interpreter • Command programming language • Backwards compatible with the Bourne Shell • Many C-shell features • /bin/ksh or /usr/bin/ksh • Executes • /etc/profile • $HOME/.profile

18. Bourne Shell – bsh • Interactive command interpreter • Command programming language • Allows for a restricted shell • /bin/bsh or /usr/bin/bsh • Executes • /etc/profile • $HOME/.profile

19. Bourne Again SHell – bash • Compatible with Bourne shell • Enhanced feature set • Command-line editing • Line completion, etc. • FREE! • /bin/bash or /usr/bin/bash • Executes • /etc/profile or /etc/bashrc • $HOME/.bash_profile or $HOME/.bashrc • $HOME/.bash_logout

20. Shell Execution Illustrated

21. Shells, Why Do I Care? • Dictates mode of operation • Allow for individual system customization

22. Your Ambassador • Interface to the Kernel • Command Interpreter • Abstracts system level details • What does this mean?

23. Interaction Details

24. What Should You Know? • How to Log on and off of a UNIX system • How the process works • What UNIX shells are • How they function in relation to the system • Some of their features

25. Question? • Anyone… anyone?

26. The File System • It’s a Directory Tree • / = root directory • Windows Equivalent = C:\ • The / serves as a directory delimiter • Can be mounted from anywhere • Everything is a file!

27. File System Commands • ls • LiSt current directory • cd • Change Directory • pwd • Present Working Directory • rm • ReMove = DELETE

28. File Types • Regular Files • Any file that can hold data, source code, binaries… • Directory Files • Special files that contain information about other files (location). • Soft/Symbolic Link “Files” • Contains a path to another file • Hard Link “Files” • Creates a link to the files inode

29. Special Function File Types • Device Files • Character Devices • Block Devices • Unix-Domain Sockets

30. Regular File Creation • FTP (get) • touch • Editor (vi, pico, etc.) • cat • echo

31. Directory File Creation • mkdir • mv • cp

32. Soft/Symbolic Link File Creation • ln –s • $ ln -s out.echo echo.out • lrwxrwxrwx msaba user echo.out -> out.echo • -rw------- msaba user out.echo • Can be made across file systems

33. Hard Link File Creation • ln • $ ln echo.out out.echo • -rw------- 2 msaba user 12 Dec 10 09:04 echo.out • -rw------- 2 msaba user 12 Dec 10 09:04 out.echo • $ ls -ial • 952410 echo.out • 952410 out.echo • Can not be made across file systems

34. File System Structure

35. What Should You Know? • How to Log on and off of a UNIX system • How the process works • What UNIX shells are • How they function in relation to the system • Some of their features • The different UNIX file types • The structure of the UNIX file system

36. Question? • Anyone… anyone?

37. Traversing the PATH • Hierarchical – Directory Tree • Parent/Child Nodes • Absolute • The full PATH /usr/local/ssh2/bin/ssh • Relative • pwd = /usr/local/bin • ../local/ssh2/bin/ssh • Simple • ssh

38. PATH • UNIX PATHs • A colon delimited list of directories the shell uses when finding a command issued with a simple PATH. • echo $PATH • Lists all of the directories the system will “look” in when a command is issued • which “command-name” • Outputs the absolute PATH of the command if known

39. PATH Shortcuts • Shortcuts to your Home Directory root • cd ~ • cd ~user-name • cd $HOME • Absolute Path Shortcuts • * • A wildcard that matches any character • cd /usr/l*/ss*

40. What Have We Covered? • What UNIX is • Logging onto UNIX • UNIX Shells • File Types • Structure of the File System • PATH

41. What Should You Know? • How to Log on and off of a UNIX system • How the process works • What UNIX shells are • How they function in relation to the system • Some of their features • The different UNIX file types • The structure of the UNIX file system • UNIX PATHS • How to navigate around the UNIX file system

42. Question? • Anyone… anyone?

43. Permissions – Power in Play • Everything in UNIX is a File • Every file in UNIX has associated permissions • Ownership • Three Ownership Tiers • User • Group • “The World” • Controls • Three Control Tiers per Ownership • Read • Write • Execute

44. Master of Your Domain • Viewing Permissions • ls –al • drwx------ 4 msaba user 512 Dec 10 09:55 . • drwxr-xr-x 27 msaba user 4096 Dec 10 09:04 .. • drwx------ 2 msaba user 512 Dec 10 09:07 dir-test • lrwxrwxrwx 1 msaba user 8 Dec 10 09:18 echo.out -> out.echo • -rw------- 2 msaba user 12 Dec 10 09:04 out.echo

45. A Closer Look • Example Data • drwxr-xr-x .. • drwx------ dir-test • lrwxrwxrwx echo.out -> out.echo • First column • File type • Next three sets of three columns…?! • Permission definitions for different ownerships

46. Binary Versus Alpha Thinkers • Binary Thinkers & Permissions • Think in terms of 0s and 1s • 0 = off/false • 1 = on/true • Convert it to decimal…Easy!! • Alpha Thinkers & Permissions • Think in terms of u,g,o,a and r,w,x • Add permissions with a + • Remove permissions with a –

47. Actually Making a Change • Grant/Change permissions • chmod • http://sp.uconn.edu/~msaba/sysadmin/Fpermissionstable.html • http://sp.uconn.edu/~msaba/sysadmin/FilePermissions.html • Changing ownership • chown user:group file

48. What Should You Know? • How to Log on and off of a UNIX system • How the process works • What UNIX shells are • How they function in relation to the system • Some of their features • The different UNIX file types • The structure of the UNIX file system • UNIX PATHS • How to navigate around the UNIX file system • UNIX ownership and permissions

49. Question? • Anyone… anyone?

50. THANK YOU FOR ATTENDING Please fill out the Evaluation Form before leaving.