Generally speaking, a network lets two or more computers communicate and work
Partly because of its open design, UNIX has been one of the operating systems
where a lot of networking development is done.
Just as there are different versions of UNIX, there are different ways
and programs to use networks from UNIX.
We don't cover networking in this book (1.32
This article has a summary of some common UNIX networking and communications
- The Internet
A worldwide network of computers.
Internet users can transfer files, log into other computers, and use a
wide range of programs and services.
The World Wide Web is a fast-growing set of information servers on the Internet.
The servers are linked into a hypertext web of documents, graphics,
sound, and more.
programs turn that hypertext into an
easy-to-use Internet interface.
(For many people, the Web is
But UNIX lets you do much more.)
A UNIX program that's been around for years, long before networking was
common, is mail
It sends electronic memos, usually called email messages
a user and one or more other users.
When you send email, your message waits for the other user(s) to start
their own mail program.
The people who get your message can file it, print it, reply to it, forward
it to other people, and much more.
System programs can send you mail to tell you about problems or give you
You can send mail to programs, to ask them for information.
Worldwide mailing lists connect users into discussion groups.
There's more, of course.
There are zillions of mail programs for UNIX-some standard, some from
vendors, and many freely available.
The more common email programs include mailx
, and MH (a package made up of many utilties including
, and so on).
that's right for you and use it!
program is one way to transfer files between your computer
and another computer with TCP/IP, often over the Internet network.
requires a username and password on the remote computer.
uses the ftp
program and a special restricted account named
on the remote computer.
It's usually used for transferring freely available files and programs
from central sites to users at many other computers.
UNIX-to-UNIX Copy is a family of programs
, and others) for transferring files and email between computers.
UUCP is usually used with modems over telephone lines.
Usenet isn't exactly a network.
It's a collection of thousands of computers worldwide that exchange
files called news articles
This "net news" system has hundreds of interactive discussion groups,
electronic bulletin boards, for discussing everything from technical
topics to erotic art.
This utility logs you into a remote computer over a network (such
as the Internet) using TCP/IP.
You can work on the remote computer as if it were your local computer.
program is available on many operating systems;
can log you into other operating systems from your UNIX
host and vice versa.
A special version of telnet
will log into
Similar to telnet
but mostly used between UNIX systems. Special setups, including a file named .rhosts
in your remote
home directory, let you log into the remote computer without typing
" program for copying files between computers.
It has the same command-line syntax as cp
except that hostnames are
added to the remote pathnames.
Starts a "r
ell" to run a command on a remote
system without needing to log in interactively.
NFS isn't a user utility.
The Network FileSystem and related packages like NIS (the Network
Information Service) let your system administrator mount remote
computers' filesystems onto your local computer.
You can use the remote filesystem as easily as if it were on your local
Sends messsages to another user's screen.
Two users can have a discussion with write
A more sophisticated program than write
screen into two pieces and lets users type at the same time if they want
can be used over networks, though not all versions of
can talk to one another.
If you'd like more information, there are quite a few books about
Some Nutshell Handbooks on networking and communications include
The Whole Internet User's Guide and Catalog
- ail, Usenet, ftp
, and more);
!%@:: The Directory of Electronic Mail Addressing & Networks
and many more advanced books for programming and administration.