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Chapter 3: Information Resources
The Internet is a global network of networks that provides access to hundreds of thousands of computers around the world. As the reach of the network has grown, so has the number of services accessible. The main tools that allow the user to navigate through the Internet are:
to access remote hosts (see section 13.2)
to retrieve data files (see section 13.1.1)
to send mail (note that Web browser mail handlers are not covered in Chapter 12)
to browse the World Wide Web (see section 3.2.1)
to scan the numerous Usenet news groups (see section 3.2.3)
There are two ways to reference an Internet host: an alphabetic name and a series of numbers. The alphabetic sequence is called the host name (e.g., fnsg01.fnal.gov) and the numeric one is called the IP address (e.g., 131.225.8.178). At Fermilab all host names end with fnal.gov, where this suffix is called the domain name. Since hosts may change their IP addresses, it is a good practice to always use the host name.
An excellent introduction to the Internet services is The Whole INTERNET, User's Guide and Catalog, published by O'Reilly & Associates.
Our primary way of delivering information to you, especially relatively static information, is via the World Wide Web (also known as WWW or "the Web"). There are a number of reasons why the Web has become the defacto standard for information delivery at Fermilab, within the HEP community, and even in the computer-literate parts of the world of business:
In order to access the Web, enter (or put in your login script):
% setup www
Web browsers work best on workstations that support graphics, so if possible you should have on your desktop a workstation, X terminal, PC or Macintosh rather than a "dumb" terminal. If you have a graphics terminal, use either Netscape or Mosaic[11]. To invoke them on an X terminal enter:
% netscape [&]
or
% mosaic [&]
The ampersand (&) is discussed in section 5.5.2. In order to use an X application (which these products are), you must have defined your $DISPLAY variable correctly. See section 9.2.
If you don't have a graphics terminal, then you must use one of the line-mode programs, lynx or www. lynx is generally thought to be the better of the two. To invoke them, enter:
% lynx
or
% www
This section is not intended to provide detailed instruction on the use of any particular Web browser. Once you get any of them running (at least the graphical ones) there is more information than you will ever want available under Help. In addition, from the UNIX Resources Web page you will find information both on using browsers and on the files that control what filetypes the browser recognizes. These files are called .mailcap and mime.types; see section 9.6 for information on them.
Web browsers find information based on URLs (Universal Resource Locators) which are like addresses and which take you to the top level of a Web site, often called a home page.
A home page usually refers to the first page of a commercial, educational, government or personal Web site. Each home page can have several layers or pages that it links to, thereby creating a whole Web site. But the home page is generally the first place you would look. It is like looking at the cover of a book and its table of contents at the same time.
The native WWW addresses are of the form:
or
The first part is the protocol, Next you'll see a colon and two forward slashes (except for Next comes the computer's address in the format described in section 3.2. A computer address, or domain name, is used by computers in routing data across the many networks that make up the Net. Finally, you often see a directory path at that computer plus a file at the end of the path. Web page files usually end in " |
Many HTML files contain links to other documents. Sometimes links are text; sometimes they are images. If a link consists of text, it is underlined and may be in color. You can tell your cursor is on a link when a URL appears at the bottom of the screen. If a link consists of an image, you'll see a URL when you move your mouse pointer across it.
Several Web search "engines" can help you find information you are seeking, and they vary in the number of URLs they contain in their database, how deep they go into Web sites indexing information, what they index, and how frequently they "crawl" or "walk" the Web in surveying sites. There's a valuable Swiss site at URL http://cuiwww.unige.ch/meta-index.html that collects several WWW search tools.
Subject directories make it increasingly easy to find information about broad subjects. An excellent directory is one called Yahoo at URL http://www.yahoo.com/, a well-constructed directory of tens of thousands of Web pages.
If you want to start writing Web pages in HTML format, see Creating Web Pages, available under Web Help on the Computing Division home page.
[Missing image]A note for Web page providers on AFS systems: Set the permissions for system:anyuser to rl on directories containing files that you want to make accessible via a Web browser. See section 7.6.2 for information on AFS directory permissions.
Your browser is most likely configured to have either the Fermilab Home Page or the Fermilab at Work page as your default home page. If not, the Fermilab Home Page can be simply accessed as: http://www.fnal.gov/. You may want to change your default home page to Fermilab at Work: http://www.fnal.gov/faw/. To do this, set your environment variable WWW_HOME as follows (environment variables are discussed in section 9.1.), depending on your shell:
C shell family:
% setenv WWW_HOME http://www.fnal.gov/faw/
Bourne shell family:
$ WWW_HOME="http://www.fnal.gov/faw/"; \ export WWW_HOME
From Fermilab at Work you can find information on Fermilab's different divisions and experiments, activities, schedules, etc. Navigate to the Computing Division's pages to find information on UNIX.
The man pages can sometimes be cryptic, unwieldy, or both. As an alternative, set a bookmark in your Web browser to UNIXHelp, accessible under the heading The UNIX Operating System on the UNIX Resources page. Here you'll find easy-to-follow instructions on the use of many UNIX features, organized into four categories: Tasks, Commands, Concepts, and Utilities.
Also from the UNIX Resources page you'll find The UNIX Reference Desk under the heading Other UNIX Resources. The resources in this document are divided into the following classes: General, Texinfo Pages, Applications, Programming, IBM AIX Systems, HP-UX Systems, Unix for PCs, Sun Systems, X Window System, Networking, Security, Humor.
Usenet News (or NetNews) is a way of communicating "articles" among people world-wide. In general, information in newsgroups is volatile information, whereas information in Web pages is of longer term. We have a server here at Fermilab which receives articles from elsewhere and posts the articles originating here. Fermilab has its own newsgroups named fnal.xxx. CERN's groups are prefixed with cern and SLAC's with slac. General information and especially important information is posted in fnal.announce. NALCAL, seminar announcements, and the like are posted in fnal.announce.seminars. Computing Division forms are in fnal.announce.forms. UNIX discussion articles are posted in fnal.comp.unix. There are many more newsgroups, both Fermilab groups and others, that you might find of interest.
In order to make a newsreader available on UNIX, enter (or put in your login script):
% setup news
A number of readers will be made available to you. Line-mode browser commands are nn, rn, and trn. X-based browser commands are xrn and knews. News may also be read from most WWW browsers and some mail readers. The readers keep track of the newsgroups that you are interested in ("subscribed to") as well as which articles in each newsgroup you have read; all of the UNIX readers cooperatively maintain this information, so you can use different readers at different times without losing this information.