The Shell Game, Part 4

Kevin O'BrienWashtenaw Linux Users Group

http://www.lugwash.org

2

BASH Shortcuts

● One way to uncover the power of the shell is by mastering the built-in shortcuts

● These let you whip through commands much faster than any GUI

● They can also do things no GUI was ever designed to do

● Remember the GUI is mostly just a front-end for running the very same commands you can run in the shell

3

Autocompletion 1● This is very handy● It will finish a command for you● You do this by using the Tab key● If there is only one possible option available,

this will fill it in for you● If there are multiple options, it will stop at the

point where it is not sure● Hit tab two times, and you get a list of the

possible options

4

Autocompletion 2

● Then you just type in however many letters are needed to remove the uncertainty, and hit Tab again to finish the autocompletion

● Example: On a Debian or Ubuntu installation you can type:

– sudo apt-get upd

– Hit Tab, and you get sudo apt-get update

– Now try sudo apt-get up

– Hit tab

5

Autocompletion 3

● This time, the shell does not know how to finish this

● When you hit tab, you may hear a bell that indicates there are multiple options

● Hit tab again, and you should seesudo apt-get upupdate upgradekevin@linuxbox:$ sudo apt-get up

6

Autocompletion 4

● What is happening here:– You first typed sudo apt-get up , and hit

Tab but the shell didn't know which command you wanted, so it stopped

– You may have heard a bell

– You hit Tab a second time, the shell gave you two possible completions

– The shell also re-entered your command so you didn't have to type it in a second time

7

Autocompletion 5

● All you need to do at this point is type a single letter at the end of this re-entered command: “d” if you wanted “update”, and “g” if you wanted “upgrade”

● Then hit Tab again and it will autocomplete

8

Autocomplete 6

● This also works for directories● If you type /uand then hit the tab, it should complete to/usr/

● You can continue through the directory tree this way. At /usr/ you could then type s and hit tab to get /usr/share/, and so on.

9

Autocomplete 7

● This is particularly helpful when you are installing software. For example, you may have downloaded a file with a name like VirtualBox-3.0.2_49928_sles10.1-1.i586.rpm

● You could try to type in the entire name, but you are likely going to make a mistake somewhere

● Autocomplete will fill it in after you type in one or two letters, in all likelihood

10

Copy and Paste 1

● You can use Copy and Paste while in the shell, or to paste in commands found outside the shell

● For example, if you go to a website, it may tell you to enter a command:wget -q http://download.virtualbox.org/virtualbox/debian/sun_vbox.asc -O- | sudo apt-key add -

● Again, you try to type this in, but it is much easier to paste it in

11

Copy and Paste 2● Copy within the shell is done by Ctrl+Shift+C● This is different from copy in most programs,

which is Ctrl+C● Paste within the shell is done by either

Ctrl+Shift+V, or Shift+Insert● This is different from paste in most programs,

which is Ctrl+V

12

Copy and Paste 3

● To copy text from a shell, you would first need to select it

● You can do this with a mouse by clicking and dragging

● Once it is selected, press Ctrl+Shift+C, then go to any other program that accepts text, and paste it in according to that program's instructions

13

Copy and Paste 4

● For example, to copy a command from a Web page into the terminal window, highlight the command on the Web page, click Ctrl+C to copy it, then go to your terminal window, and press Ctrl+Shift+V to paste it in, and hit enter

● This will run the command● If you need elevated rights, you could type in sudo, followed by a space, before pasting in the command

14

Conclusion

● Autocomplete and Copy and Paste are great ways to be more efficient in the shell

● You should practice using these techniques● The best efficiency gain is when you have

them in your brain so well that you don't need to think much about them, and that only comes with practice