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2. Typing Unix Commands |  |
| 2.2. Special Characters | ||
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2. Typing Unix Commands | |
As you type, some characters have a special meaning. For example, if you have entered the first few letters of a file name and hit the “Tab” key, the shell will examine what you have typed so far and attempt to complete the filename by filling in the remaining characters. If the shell is unable to complete the filename, a bell or beep sound will be given. Even in this case, the shell will fill in as many characters as it can.
Most special characters are entered by holding down the “Control” key while typing a letter. By convention, we designate this by placing the symbol “^” in front of the name of the second key. For example, if you have typed zero or more letters of a filename and want to see a list of what filenames begin with what you have typed, you could type ^D, i.e., hold down the “Control” key and type “d”.
Some other useful special keys are:
^C is used to abort a program/command that is running too long or working incorrectly. Beware: aborting a program that is updating a file may leave garbage in that file.
^D is used when a command/program is reading many lines of input from the keyboard and you want to signal the end of the input.
^H, the “Backspace” key, and the “Delete” key all delete the most recently typed character.
^B moves the cursor Backwards over what you have just typed, without deleting those characters. This is useful in correcting typing mistakes. The “left” arrow on your keyboard may also do the same thing.
^F moves the cursor Forwards over what you have just typed, without deleting those characters. The “right” arrow on your keyboard may also do the same thing.
^P retrieves the Previous command that you had typed in. Repeated ^P's may be used to look back through a number of commands that you have issued recently.
The “up” arrow on your keyboard may also do the same thing.
^N is the opposite of ^P. After one or more ^ P's, a ^N allows you to move back to the Next more recent command.
The “down” arrow on your keyboard may also do the same thing.
In many programs, ^Z pauses the program and returns you
temporarily to the shell. To return to the paused program, give the
command: fg
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| 2.1. Command Arguments | 2.3. One Pattern, Many Instances |