Files, folders, directories, URLs, and IP addresses

1. Files, folders, directories, URLs, and IP addresses Craig L. Zirbel Math 592 Spring 2008 Math 592 Spring 2008

2. File Structure • How to think of where files are stored, how they are grouped • Either think of it as a tree or a nested structure Math 592 Spring 2008

3. Macintosh / Windows • Graphical interface organizes files into nested folders. Data Adobe Windows Videos C drive Math 592 Spring 2008

4. Paths and filenames in windows • Each file has a text string that tells where it is • C:\WINDOWS\DATA\DATAFILE.DAT • Everything before the filename is called the path • The letters at the end, after the last period, are called the extension Math 592 Spring 2008

5. Paths and filenames in windows - 2 • In the original DOS (Disk Operating System), filenames and directory names could be no more than 8 letters long, and extensions only 3 letters. • Case was ignored, and all files were stored with uppercase. • This still persists, to some degree. Math 592 Spring 2008

6. UNIX versus DOS • Files are grouped into directories, not folders • Directories can contain files or other directories • DOS: C:\WINDOWS\DATA\DATAFILE.DAT • UNIX: /25/zirbel/public_html/592/index.html • UNIX is case sensitive! Index.html differs from index.html • Think of it as a tree: 1 2 jsmith 591 public_html zirbel 592 25 index.html Math 592 Spring 2008

7. Accessing your files on personal.bgsu.edu • When you have an account on personal.bgsu.edu, you have permission to put files, change files, and view files in a certain directory. • Mine is /25/zirbel • Let’s use WS_FTP to poke around a bit … Math 592 Spring 2008

8. My “root” directory Math 592 Spring 2008

9. My public_html directory Math 592 Spring 2008

10. The 592 directory Math 592 Spring 2008

11. The /25 directory Math 592 Spring 2008

12. Change directory using ~zirbel • This is how to refer to your root directory even when you don’t know the complete path to it. Math 592 Spring 2008

13. Cannot change to ~yonglin Math 592 Spring 2008

14. Networking and addresses • personal.bgsu.edu is the network name of a computer • Following the syntax for paths and filenames, edu.bgsu.personal might be more appropriate, because it would go from general to specific. • personal.bgsu.edu/~zirbel refers to zirbel’s public_html directory, not zirbel’s root directory. • personal.bgsu.edu/~zirbel/592/index.htm • Case is important in filenames! Math 592 Spring 2008

15. IP (Internet Protocol) addresses • Computers use numbers instead of words to identify computers on the network. Each has its own. • personal.bgsu.edu is 129.1.2.169 • Bgunix.bgsu.edu is 129.1.3.10 • When connected, my laptop is 129.1.87.20 • Webmail.bgsu.edu is 129.1.5.20 • Everything at BGSU begins with 129; here we go from general to specific. Math 592 Spring 2008

16. File transfer protocol • There are programs that allow you to transfer files back and forth between two network computers • ftp on Unix and Windows • WS_FTP and WinSCP have GUI’s • Fetch on the Macintosh • Specify the remote computer and identify your username, give your password Math 592 Spring 2008

17. Web browsers • These programs can bring certain files from a remote computer to your local computer and display them. That’s all they (used to) do! • The convention is that only files in a directory called public_html in your main directory are accessible to web browsers. • If you just specify a path, like http://personal.bgsu.edu/~zirbel it will assume you want the file called index.html or index.htm Math 592 Spring 2008

18. Internet Terminology • URL Uniform Resource Locator • http: is a scheme name. It requests a Hypertext Transfer Protocol interaction. • //personal.bgsu.edu is the domain name • ftp: is another scheme, which requests an FTP interaction with the computer • telnet: requests an interactive terminal window, like the DOS command prompt Math 592 Spring 2008

19. Operating systems • UNIX • DOS/Windows • Macintosh • LINUX Math 592 Spring 2008

20. UNIX • Developed since late 1960’s • Volunteer effort, in part • Many useful utility programs, including sendmail • Stable, security against hackers • Networked for years! • Many (most?) web servers run UNIX Math 592 Spring 2008

21. DOS / Windows • Developed since early 1980’s • Fairly open standard, so other companies can write software for it • Not much security until recently • Relatively new to networking • Many ways for hackers to break in, many hackers working on it Math 592 Spring 2008

22. Macintosh • Developed by Apple since the early 1980’s • Closed standard; only Apple can write software for it • Reasonably good for small networks • Too small for hackers to worry about much Math 592 Spring 2008

23. LINUX • A version of UNIX that can be installed on a PC • Virtually free • A strong competitor for Microsoft • Now the basis for Macintosh OS X Math 592 Spring 2008