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Becoming root (command line)
The most flexible way of performing actions as root is using the terminal (command line), which lets you be root while the rest of your system is still in limited user mode.
To open a terminal, look in the menu system > terminals. To temporarily use the root account, simply type su and hit enter. You may be prompted for the root password you set up during installation. Type it, and hit enter (you will not see it printed on the screen as you type; this is a normal security measure). When you hit enter, if you got the password right, you should see a prompt, as before, but instead of a $ sign at the end, you will see a # sign. This is a reminder that you are currently using the root account. Whenever you see # as the final character of a prompt, you are currently working as root.
You can now run whatever commands you need to run. Note that any command you run when working as root will have the same rights: if you run a graphical file management tool, for instance, it will be able to access and delete files that it could not if you ran it as normal from the desktop.
Once you have finished, you should return to your normal user account by typing exit and hitting enter. The prompt will change back to a $ sign to let you know you are using your normal user account again.
Becoming root (graphical interface)
To run a graphical tool as root, you must first know what command invokes it. You can find out by viewing the properties of a shortcut or link to it. For example, to run the graphical package manager as root, go to the menu system > configuration > packaging, right-click on "Browse Available Software", and click "Edit item". In the box labeled "Command", it should say something like /usr/sbin/rpmdrake. To browse files as root, right-click on "Devices" on your desktop, go to the "Application" tab, and copy the text in the box labeled "Command" (which should say something like konqueror --profile devices media:/).
Once you know the command, open a terminal (command line) from the menu system > terminals. Become root by using the instructions above (essentially, type su, then your root password if prompted). Type in the command you found in the "Command" box above. For example, to run the graphical package manager as root, type in /usr/sbin/rpmdrake. The graphical tool will then launch with root privileges.