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connecting to a shell

summary

    This subchapter looks at connecting to a shell.

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connecting to a shell

    This subchapter looks at how to connect to a shell.

    If you are connecting to a remote computer (such as web server), then you can use telnet or SSH.

    If you connecting to the shell from a modern graphic user interface, then you need to start up a terminal emulator.

    If you connecting to a mainframe computer, minicomputer, or the equivalent, you use any terminal connected to the system.

physical terminal

    For old style systems where UNIX runs on a mainframe or minicomputer, there will be actual physical terminals that are connected by wires or MODEM to the mainframe or minicomputer. These systems are increasingly rare.

    The terminal may already be at the login prompt. If not, try pressing the RETURN key several times until the login prompt shows up.

Telnet and SSH

    telnet or SSH are the two basic methods for connecting to a remote server.

    telnet was the original method. There are telnet client programs available for most computer systems. Unfortunately, telnet performs all communications in plain text, including passwords, which means that anyone malicious along the path between you and your server can easily read the information needed to hack into your system using your account. For this reason, many servers no longer allow telnet access.

    SSH is Secure Shell. It has the same basic capabilities as the older telnet, but includes security, including encrypted communications. There are SSH client programs for most modern computer systems.

    You can also use SSH through a terminal emulator, which is how many system administrators now access their servers from their personal or portable computer.

terminal emulator

    As mentioned in the history subchapter, the UNIX shells were accessed through interactive terminals, originally teletype machines and later special combinations of keyboards and cathode ray tubes (CRTs).

    There are programs for graphic user interfaces that allow you to interact with a shell as if you were using one of those ancient terminal devices. These are called terminal emulators (they emulate the signals of a terminal).

    Some common terminal emulators include eterm, gnome-terminal, konsole, kvt, nxterm, rxvt, terminal, and xterm.

    Note that if you are logging in to a web server or other remote computer, you should use an SSH (Secure SHell) client program instead of a terminal emulator. A terminal emulator program is for gaining shell access to a personal computer or workstation. With a little bit more knowledge, you can use the shell on a personal computer or workstation as your SSH client.

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