The Terminal & Getting Help

On a desktop Linux system, which terminal-emulator programs are you most likely to find, and how do they split by desktop environment?

You select some text in a terminal window and press Ctrl+C to copy it, but nothing lands on the clipboard. Why, and what should you press instead?

You click in the middle of a long command line in a terminal, expecting the cursor to move there like in a GUI text box. What does the mouse actually do in a terminal?

In Linux documentation you often see command examples prefixed with user$ or root#. What do these prefixes mean and how should you treat them when typing?

A long command is printed across two lines, the first ending with a backslash. What does that trailing backslash do, and what must you change if you retype it all on one line?

Logged in as a normal user, you need to run a whole series of commands as root without prefixing every one. What is the usual way to get an interactive root shell, and how do you leave it?

A command like ls -l or ps ax produces far more output than fits on one screen. How do you page through it comfortably at the terminal?

You're on a stripped-down embedded box (a NAS) and less isn't installed. Which fallbacks let you view a text file, and how do cat and tail differ from a pager?

You accidentally cat a binary file and now the terminal shows nothing but garbage characters — even normal text looks corrupted. How do you fix it without closing the terminal?

You're reading a long file in less and need to find a word further down, then jump to the next match. Which keys search forward, search backward, and repeat?

You need to edit a config file at the console but don't know vi and want something forgiving. Which editor fits, and how does it help you learn its commands?

In GNU Emacs, what are the core keystrokes to open a file, save it, exit, and abort a half-typed command?

You type vi on a modern Linux box. Why is it noteworthy that you almost never get the actual original Vi editor?

A newcomer opens vi, starts typing, and gets beeps and characters interpreted as commands instead of text. What is the fundamental thing about vi they're missing?

In vi command mode, you delete a line by mistake. Which keys delete a line, delete a single character, put a deleted line back, and undo the last change?

You've made edits in vi and want to leave. What is the difference between :wq and :q! — and how do you save under a different filename?

A program like your version-control tool or crontab keeps popping you into vi, but you'd rather it used another editor. How do you change the default editor system-wide?

You need help on a command at the terminal. What's the difference in what command --help, man command, and help command each give you?

You run man printf hoping for the C library function's prototype, but get the shell command instead. How do you tell man which one you mean?

You keep seeing references like find(1) or printf(3) in Linux documentation. What does that parenthesized number tell you, and how do you view every same-named page in turn?

The man section numbers aren't arbitrary — what do sections 1, 2, 3, 5, and 8 cover, and why does that matter when a name appears in more than one?

Where does man look to find its pages, and what program does it actually use to show them on screen?

Some GNU tools ship their real documentation as info pages rather than man pages. How do you open info, navigate cross-references, and what practical limitation should you expect?

On a headless server with no desktop, you try to select and copy text with the mouse in a pure text console and the mouse does nothing. What is missing?

The graphics system has crashed and you are dropped to text mode. You need to reach the second text console, then jump back one console. Which key combinations get you there?

A command dumped pages of output to a text console and it has already scrolled off the top of the screen. How do you look back at it without re-running the command?

You are done working in a text console, or want to log in under a different name. What is the quickest way to log out of the current console session?

In a Linux text console you reflexively press Ctrl+Alt+Del the way you might on Windows to open a task menu. What actually happens?

What is the practical payoff of Linux giving you several independent text consoles rather than one?

You're on a text-only server and need to read a web page or turn an HTML file into plain text. Which tools handle this, and what's the one-liner to convert HTML to text?

Mutt is a text-based email client. Where does it read local mail from by default, and what must you change if your mail is stored in Maildir format instead?

A colleague suggests replacing ls, cat, find, and du with newer tools like eza, bat, fd, and ncdu. What's the one big caveat before you wire these into your scripts?

You want a quick, example-driven reminder of how to use a command without wading through its full man page. Which tool is built for that?

You launch Lynx in a Unicode terminal and special characters come out garbled, plus you'd like to click links with the mouse. Which two options fix these, and what's Lynx's default character set?

You drop from the desktop to a text console but the first two consoles seem to be taken. On a typical distribution, which consoles are occupied, how do you reach a free login prompt, and how do you get back to the desktop?

The menu bar in gnome-terminal is gone and there's no obvious button to bring it back. How do you toggle it off and, more importantly, get it to reappear?

Which gnome-terminal keyboard shortcuts open new windows and tabs, move between tabs, and change the font size?

You set an eye-friendly light background in your terminal and suddenly some command output is hard to read. Why does that happen?

The joe editor can behave like Emacs or like nano depending on how you launch it. How does that work, and where do you find its help?

Several programs on your system provide the same kind of tool (multiple editors, multiple Java runtimes). What mechanism lets a distribution pick one as the system default?