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Formatting Information — An introduction to typesetting with LATEX

Appendix B: Commands and errors

Section 1: LATEX from the Terminal

Originally a terminal was a screen and a keyboard, looking very much like a standard desktop computer in the days before flat screens and windowing systems. There are still a surprising number of these around (see Figure B.1 below). The important point is that it was (is) a text-only interface to the computer. You got 25 lines of 80 fixed-width white-on-black or green-on-black characters, no fonts, no colours, and no mouse; maybe reverse-video as a form of highlighting.

Figure B.1: Text-only display terminals


Images courtesy of Wikipedia. Left: IBM 3279 display by Retro-Computing Society of Rhode Island (CC BY-SA 3.0); Right: DEC VT100 terminal by Jason Scott (Flickr IMG_9976, CC BY 2.0), at the Living Computer Museum (apparently connected to the museum’s DEC PDP-11/70).

Nowadays the word ‘terminal’ usually means a ‘virtual terminal’: a window that behaves like a terminal — 25 lines of 80 fixed-width characters in monochrome (see Figure B.2 below). It’s a window into the heart of your computer. Even though you still have all your other windows visible, it knows nothing about them and can’t interact with them (except for copy and paste). But instead of being a padded cell, most terminals can do things many other windows can’t, like handling files in bulk, or to a schedule, or unattended, even forcing things to happen even when the graphical world outside has got itself jammed solid.

B.1.1 So where is the terminal window?

Apple Macintosh OS X

Click on FinderApplicationsUtilitiesTerminal;

Microsoft Windows

Click on the Windows or Start button, All ProgramsAccessoriesTerminal (in older versions it’s called Command Prompt, in some newer ones just Command)

Unix and GNU/Linux

In most graphical interfaces, click on the menu ApplicationsAccessoriesTerminal (in some systems it’s called Console)

When you have finished using the terminal, it’s good practice to type exit (and press Enter).

B.1.2 Using the terminal window

On a physical terminal you usually have to log in first (very much like today: username and password). In a terminal window this isn’t usually necessary (see Figure B.2 below) because it’s inside your graphical system, and you’ve already logged in to that.

Figure B.2: Virtual terminal in a window


In this example I’m logged into a computer called nimrod with my username peter. The system prompt is the directory name plus a dollar sign (the tilde indicates that I’m in my home directory system). For visibility, I underlined in red here the commands I typed, one to change to my Documents folder, and one to run XƎLATEX on the quickstart.tex document.

The first thing you see is the prompt (usually a dollar sign or percent sign, or maybe a greater-than pointer C:\> like MicroSoft Disc Operating System (MS-DOS) used to use). When the prompt appears, you can type an instruction (command) and press the Enter key at the end of the line to send if off to the computer for processing. Until you press  Enter, the computer has no idea you’ve finished typing: you MUST press Enter at the end of each line of command for it to take effect.

The results, if any, are displayed on the screen, and the prompt is displayed again ready for your next command. Some commands don’t have any output: if you change directory or delete a file, for example, you just get another prompt. There’s no message confirming the action, and no check to see if you really meant it. You said to do it, and it’s done.