1. man
2. ls
Another fundamental command is "ls," which displays the contents of your current directory. For example, "ls " will show you the files in your home directory.
3. pwd
To find out which directory you're working in, type "pwd," which is short for "print working directory." Typed in the desktop directory, for example, this command will return "/desktop."
4. cd
To change the directory you're in, use this command. To switch to the desktop directory, for instance, you'd type "cd desktop."
5. mkdir
To create a new directory, this is the command you'd use. For example, "mkdir pictures" will create a directory called "pictures."
6. find and locate
To search for a file, you can use either "find" or "locate," both of which are very similar.
7. cp
This is the command to use when you want to create a copy of a file with a new name. Type "cp cats dogs," for instance, and you'll get an exact copy of "cats" named "dogs"; the file "cats" will still be there too.
8. mv
With "mv," you can change the name of a file or move it to another directory--or both. Typing "mv cats dogs" will rename the file "cats" to "dogs," for example, while typing "mv cats /desktop" will move the file "cats" to the desktop directory without renaming it.
9. more
The "more" command allows you to see the contents of a file one screen at a time.
10. kill
When you want to stop an application, there's no more efficient way to do it. Typically "kill" is used after "ps," which lets you find out the process ID of what you want to kill.
11. sudo
Part of the reason Linux is so secure is that only the root user has the privileges needed to install or remove applications and make other big changes. To install an application as a regular user, the sudo command can give you those root privileges temporarily. You will, however, have to enter your password.
12. passwd
Need to change your password? Then just type this command at the prompt, and it will ask you to type the current password and then a new one.