442 CHAPTER 30 MANAGING USERS Alternatively, by adopting superuser powers, a user can change the password of another account: sudo passwd This is necessary just after you create a new user account because it isn t given a password automatically. For obvious security reasons Ubuntu won t allow blank passwords. You can enter just about anything as a password, but you should bear in mind some common-sense rules. Ideally, passwords should be at least eight characters long and contain letters, numbers, and even punctuation symbols. You might also want to include both uppercase and lowercase letters. A number of command options can be specified along with the passwd command when it used with superuser powers. For example, the -l option will lock the specified account so that it can t be accessed (the -u option will unlock it). Tip You can temporarily switch into any user account by typing su . When you ve finished, simply type exit to return to your own account. Summary In this chapter, we looked at the principles behind user and group accounts under Ubuntu. We ve examined how user and group accounts can be created, edited, and deleted using the GUI, as well as the command-line prompt. We also looked at how passwords can be manipulated by the individual users themselves and by a user with superuser powers. In the next chapter, we ll look at how the system can be optimized. You ll also learn about several interesting and important system tools.
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