Depending on which program you are using, sometimes you must press Enter (or Return) after a command, and sometimes you don’t. In the UNIX shell, you always have to press Enter or Return before UNIX performs the command. If you don’t, UNIX waits forever for you to do so.
In other programs, particularly in text editors like
emacs and
vi , as soon as you press the command (Ctrl+K to delete a line in
emacs , for example), the program does it right away. If you press Enter or Return after the command,
emacs sticks a new line in your file, and
vi moves down to the next line.
Tip When you use a program you’re not familiar with, hesitate a moment before pressing Enter or Return to see whether the computer may already be performing the command. If nothing is happening, press Enter or Return.