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Shell account

Shell account is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Shell account rather than just read about it. In short: A shell account is a user account on a remote server, typically running under Unix or Linux operating systems. The account gives access to a text-based command-line interface in a shell, via a terminal emulator.

Shell account — main illustration
Shell account — illustration

Key takeaways

  • Shell account belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Shell account to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Shell account from memory before moving on to harder problems.

Reference excerpt

A shell account is a user account on a remote server, typically running under Unix or Linux operating systems. The account gives access to a text-based command-line interface in a shell, via a terminal emulator. The user typically communicates with the server via the SSH protocol. In the early days of the Internet, one would connect using a modem. Shell accounts were first made accessible in the 1980s to interested members of the public by Internet Service Providers—such as Netcom, Panix, The World, and Digex—although in rare instances individuals had access to shell accounts through their employer or university. They were used for file storage, web space, email accounts, newsgroup access and software development. Before the late 1990s, shell accounts were often much less expensive than full net access through SLIP or PPP, which was required to access the then-new World Wide Web. Most personal computer operating systems also lacked TCP/IP stacks by default before the mid-1990s. Products such as The Internet Adapter were devised that could work as a proxy server, allowing users to run a web browser for the price of a shell account. While direct internet connections made shell accounts largely obsolete for most users, they remained popular with some technically inclined subscribers. Shell providers are often found to offer shell accounts at low-cost or free. These shell accounts generally provide users with access to various software and services including compilers, IRC clients, background processes, FTP, text editors (such as nano) and email clients (such as pine). Some shell providers may also allow tunneling of traffic to bypass corporate firewalls.

See also Bulletin board system FreeBSD jail Free-net SDF Public Access Unix System, one of the oldest and largest non-profit public access UNIX systems on the Internet. Slirp, a free software application similar to The Internet Adapter SSH tunneling The Big Electric Cat was a public access computer system in New York City in the late 1980s, known on Usenet as node dasys1. The Internet Adapter, a graphical application front end for internet access using shell accounts allowing TCP/IP-based applications such as Netscape to run over the shell account. The WELL, best known for its Internet forums, but also provides email, shell accounts, and web pages.

References

External links Shell providers list

Illustrations

Shell account: irssi IRC client running on a shell server
irssi IRC client running on a shell server

Worked examples

Example 1 — a first encounter with Shell account

Start with the simplest possible case. Write down what Shell account claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Shell account before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Shell account ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Shell account

In research
Shell account appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Shell account in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Shell account is common in secondary-school and first-year university syllabi. It links to neighbouring topics Internet hosting, Shell account providers, Unix, so understanding it makes those chapters shorter.
In everyday life
Look for Shell account outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Shell account in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Shell account means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Shell account out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shell account in simple terms?

A shell account is a user account on a remote server, typically running under Unix or Linux operating systems. The account gives access to a text-based command-line interface in a shell, via a terminal emulator.

Why does Shell account matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Shell account?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Shell account.

Tags

  • Internet hosting
  • Shell account providers
  • Unix

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