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[Chapter 3] Users and Passwords
Alternatively, John might have a username that appears totally unrelated to his real name, like avocado
or t42. Having a username similar to your own name is merely a matter of convenience.
Most organizations require that usernames be at least three characters long. Usernames that are only one
or two characters are valid, but they are usually discouraged. Single-character usernames are simply too
confusing for most people to deal with, no matter how easy you might think it would be to be user "i" or
"x". Usernames that are two characters long are easily confused between different sites: is
mg@unipress.com the same person as mg@aol.com? Names with little intrinsic meaning, such as t42
and xp9uu6wl, can also cause confusion, because they are more difficult for correspondents to remember.
Some organizations assign usernames consisting of a person's last name (sometimes with an optional
initial). Other organizations let users pick their own names. A few organizations and online services
assign an apparently random string of characters as the usernames, although this is not often popular with
users or their correspondents: user xp9uu6wl may get quite annoyed at continually getting mail
misaddressed for xp9uu6wi, assuming that anyone can remember either username at all.
UNIX also has special accounts which are used for administrative purposes and special system functions.
These accounts are not normally used by individual users, as you will see shortly.
II. User Responsibilities 3.2 Passwords
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