How can I create an alias so that when I enter "kt" it executes "killall gnome-terminal"?

Creating an alias

• To add an alias type the following in terminal,it will work until you close your terminal.
  alias kt='killall gnome-panel'
• To add this alias permanently you have to add the above command into .bashrc file
  gedit ~/.bashrc
• Add the first command at the end of your .bashrc file,
  
• To refresh your .bashrc file type the following in terminal,
  . ~/.bashrc or source .bashrc
• Now you can type kt in terminal it will perform the action of killall gnome-panel
• To list all your aliases type alias in terminal.
  

Few examples:

• To create an alias for update,you have to add the following to your .bashrc
alias update='sudo apt-get update'
• For upgrade
  alias upgrade='sudo apt-get upgrade'
• To add both update and upgrade you can do the following
  alias upd='sudo apt-get update && sudo apt-get upgrade'

Note:

• Source command is used for applying the changes that you have just made in a configuration file.
• By ændrük suggestion you can also put your custom aliases in ~/.bash_aliases

Just type alias kt="killall gnome-terminal" in command line (I assume you're bash user).

To make this changes permanent, you can put this line to your .bashrc, for example. Execute echo 'alias kt="killall gnome-terminal"' >> ~/.bashrc (don't forget to re-apply changes using . ~/.bashrc)

Use simple alias command to see the list of aliases in action.

Cheers

update: BTW, you may find this useful as well: Problem with creating permanent alias