Command Line Tips subpage

Does a command line make you nervous?

Don't be intimidated, you're in charge

The command line has a reputation for being difficult. There is a lot to learn .. some years' worth, probably, that is if your goal is to become a guru-level command line master. But the encouraging counterpoint is that like many skills, once you get past an initial learning threshold, the benefits start making a real difference in your (computer) life.

Aside from reputation, the command line may be intimidating at first because there's no visible hints about what to do next. Actually instead of the GUI menu and icon crutches, there are good command line substitutes (covered elsewhere, so keep on reading :-) ).

The next couple subsections on this page should also help allay any "fear-of-flying" issues.

Getting a CLI (command line interface)

For most people today, their computer boots into a GUI (graphical user interface), and discussion of CLI may not even mean anything obvious. In the olden days there were pure 25-line by 80-column text mode interfaces, and even today you can get your Linux box to boot into text mode, if you really want to. Not only that, but you can still switch to one of these pure-text virtual terminals via the Ctrl-Alt-Fn (n=1,2..,6) key combination. If you do that, remember that Ctrl-Alt-F7 will return you to the GUI.

In GUI mode, there is a terminal emulator capability that one usually means when speaking of the command line. In fact there are many programs that provide a CLI via terminal emulation. Frequently one refers to such programs as xterms, after one of the oldest terminal emulators in the Unix X-windows environment. Over the years, a number of these xterm-like programs have appeared, but in recent years the trend has been to fancier (tabbed multi session) programs named terminal, konsole or gnome-terminal. In current distros, opening a terminal will result in one of these programs running. Most will also let you run xterm if you want to see what that looks like. In Fedora 7, the terminal menu entry is located under Applications > System Tools. In Ubuntu 7.04, it's under Accessories. Both are gnome (diffferent versions of gnome-menus). In a GUI, the terminal emulators are programs that run in a regular gui window (resizable, for example). In KDE, the menu choice seems to be System > Konsole (Knoppix: System > Shells > Bash).

I use the CLI so much, I have put the terminal on my panel. When you find the menu choice, right-click to see the context menu containing "Add launcher to panel".

Note: Be aware that running a terminal, using a command line interface, and similar expressions all imply that a prorgam is running to interact with you, the user. Such a program is called a shell (sometimes a command line interpreter). There are multiple shell programs (sh, bash, zsh, ksh..) each with their own user interface differences. The default shell in Linux is bash. Also, The term "shell" is sometimes used interchangeably with CLI.

Getting into/out of trouble

surprises and disconcerting behavior

• accidental close .. probably caused by inadvertent entry of Ctrl-D:

    I have *export IGNOREEOF=3* in my "profile" (discussed elsewhere)
  
    If you do this, then typing Ctrl-D causes a help message to be output,
    and the Ctrl-D is otherwise ignored (unless you type more than 3-in-a-row)
  
    The help message tells the normal way to quit a terminal (typing "exit")
  

• unexpected (perhaps overwhelming) program output .. Ctrl-C (usually) terminates
• the terminal screen prompts and echoes gibberish .. try typing blindly:

     <ENTER>reset<ENTER>
  

• terminal does not respond to input .. try:

     ensure terminal window has *focus* by clicking the mouse in the window
     try typing Ctrl-Q (cancels effect of Ctrl-S, a pause operation)
  
     just to illustrate how this looks and works.. 
     ..try this (produces endless but harmless output):
       while :; do echo $((I+=1)); done
     then press Ctrl-S to pause, Ctrl-Q to resume, Ctrl-C to quit
  

• terminal behaves strange on bottom line .. try resizing the window slightly, try clear (or Ctrl-L), try reset
• if all else fails kill the terminal window with the window close widget

It really is worth it

• a major convenience in some cases, indispensible in other cases ...
• powerful, versatile, ... if you want/need it to be
• natural, enabling, ... if you use a computer for multiple general purpose activities
• required skill ... for a professional or advanced user capacity