Files, folders, directories, URLs, and IP addresses Craig L. Zirbel Math 592 Spring 2008 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

Macintosh / Windows Graphical interface organizes files into nested folders. Data Adobe Windows Videos C drive 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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. 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 … 9/16/2018 Math 592 Spring 2008

My “root” directory 9/16/2018 Math 592 Spring 2008

My public_html directory 9/16/2018 Math 592 Spring 2008

The 592 directory 9/16/2018 Math 592 Spring 2008

The /25 directory 9/16/2018 Math 592 Spring 2008

Change directory using ~zirbel This is how to refer to your root directory even when you don’t know the complete path to it. 9/16/2018 Math 592 Spring 2008

Cannot change to ~yonglin 9/16/2018 Math 592 Spring 2008

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! 9/16/2018 Math 592 Spring 2008

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. 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

Operating systems UNIX DOS/Windows Macintosh LINUX 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008

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 9/16/2018 Math 592 Spring 2008