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Mastering UNIX Basics: File Systems & Commands

Dive into UNIX basics with this tutorial covering file systems, command-line maneuvers, shells, and system access. Learn essential commands, ownership, and permissions for efficient navigation and management. Discover the fundamental aspects of UNIX distributions and their capabilities for networking and portability. Gain insights into different shell types, their features, and functionalities for system operation. Explore file system structures and creation methods while understanding different file types and paths traversal in UNIX environments.

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Mastering UNIX Basics: File Systems & Commands

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  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.

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