When Mac OS X first appeared, a lot of
people were aghast at the concept of user accounts, especially when
they were the only ones using their computer. "Why
go through all the hassle when only I exist?" they
asked. The complaints only intensified as users were asked to enter
an administrator password [Hack #50] for access to certain files, sometimes even
denied access to settings and files on their very own computers
— the gall of it!
The reasoning is two-fold: to protect you from yourself and to
support Mac OS X's multiuser environment.
The concept of protecting you from yourself may at first blush appear
intrusive, but we've all had an instance where
we've deleted an innocent file from our OS 9 System
Folder, only to discover our idiocy when our system
didn't reboot, our printer didn't
print, or our modem didn't sizzle. In this regard,
OS X has your back; crucial files necessary for everyday operation
are protected from overzealous removal.
The multiuser environment of OS X is based on technology
that's been around for a while in the Unix world: a
system of checks and balances that stop your kid sister from
gleefully deleting that Photoshop file you've been
working on all weekend. Whether you're the only user
isn't a concern; protection from the inside
(yourself, your kid sister) and protection from the outside
(malicious crackers, viruses, and trojans) becomes paramount.
While a determined user can delete any file on their OS X machine
with enough effort (the easiest way being to boot into OS 9), Apple
has wisely made it difficult to do so through Mac OS X.
What's in a Name?
When creating an
account (System Preferences → Accounts → New User .
. . ) — either the initial account upon installing Mac OS X, or
an additional account — you'll be prompted for
both your Name (e.g., John Jacob Jingleheimer Schmidt) and something
called a Short Name.
Figure 1. Selecting a Name and Short Name
Your Short Name is your actual username, or login
name, the name by which your computer knows you. It is
usually three to eight characters long, composed of letters or
numbers. While OS X attempts to choose a Short Name for you based
upon what you entered as your Name, it doesn't do a
particularly good job if your name isn't as simple
as Sam Smith. And, trust me, you don't want to spend
your days being known by your computer as
johnjacobjingleheimerschmidt. Choose something short and quick to
type, like john, johnj, or schmidt. Here's why . . .
Your Home Directory
Your home directory is where
you'll be keeping all your stuff. In it you'll find special
directories for your documents, pictures, movies, and settings
(that's what the Library is).
Of course, you're not forced to organize your stuff
this way, but it is a good convention. Feel free to settle in, create
new folders, and shuffle things about. It's
generally a good idea not to throw out the special
folders, as the operating system and
its applications often make use of them and expect them to be there.
In particular, don't touch your
Library folder; it's the home
of your preferences, settings, and other
pieces used by particular applications.
Figure 2. Finder view of a typical home directory
If you chose john as your Short Name, then your home directory will
be Macintosh HD → Users
→ john. By creating a
central place for all your important data, OS X ensures easy backup
or deployment on other machines. Instead of having to single out your
favorite control panels or extensions from OS 9, you can simply
backup your home directory. When you're ready to
restore, simply copy it over to the same location, and your
environment (iTunes music library, desktop pictures, added software
tweaks, etc.) will take effect the next time you log in.
From the command
line's [Hack #48] point of view, your
home directory — again, assuming your Short Name is john
— is /Users/john. You'll
sometimes see it referred to on the command line as
~ .
It's a shortcut that saves you from having to type
out your full login name when referring to your home directory. So
~/Documents actually refers to
/Users/john/Documents (Macintosh HD
→ Users →
john → Documents
in the Finder).
Who's the Boss?
As the primary user of your computer,
you're automatically afforded administrative
privileges [Hack #50], which means that you can
install just about any software, modify settings affecting how OS X
functions, and create and delete other accounts. Needless to say, if
you don't want your kid sister messing up your
computer, you shouldn't make her an administrative
user. Give administrative access only to those people (read:
accounts) that truly need it.
Renaming an Account
While OS X makes it easy to create new
accounts, alter their capabilities, or change and delete their
passwords, it's less than helpful when it comes to
renaming an account (i.e., changing
its Short Name). In fact, there's simply no way to
do so from the GUI side of things. To do so, you'll
have to do some of the work on the command line.
For example, let's fix our earlier
johnjacobjingleheimerschmidt bungle, renaming the account (a.k.a.
Short Name) to john.
First, create a brand-new account (System Preferences →
Accounts → New User). OS X won't allow you
to enter the same Name, so change it slightly for now;
you're always able to change the full name. I chose John Jacob Jingleheimer
Schmidt II as a placeholder. For Short Name, choose something
reasonable. Again, I chose the more sensical john, since I know
he'll be the only John using my computer and I
don't expect much confusion about
who's who.
Figure 3. Creating a new account
Next, you'll need to pull a switcheroo, giving a
copy of johnjacobjingleheimerschidt's home directory
to john to use as his own. Since you'll be making a
copy rather than permanently pulling
johnjacobjingleheimerschidt's home directory out
from underneath him, you'll be able to verify that
all is as it should be before deleting anything potentially valuable.
TIP
Before moving on, you should make sure that you have enough hard
drive space to hold both copies. Compare the size of the home
directory to the amount of available space on your drive using Get
Info (File → Get Info) on each.
All of this must be done as the administrative (or root) user, as
you'll be manipulating files belonging to two other
accounts. If you have not already done so, enable the root user [Hack #50] and log in as root.
Navigate in the Finder to Macintosh HD
→ Users.
First, you'll
remove john's home directory; don't
worry, since it's brand new, it
doesn't contain much of any worth. Drag the
john folder to the Trash.
That
out of the way, duplicate the
johnjacobjingleheimerschmidt directory by
Control-clicking it and selecting Duplicate from the context menu, as
shown in , and rename it to
john.
Figure 4. Duplicating johnjacobjingleheimerschmidt's home directory
Figure 5. Renaming the copy of johnjacobjingleheimerschmidt's directory to john
john and johnjacobjingleheimerschidt now own identical home
directories.
About the only bit you don't want to be identical is
the keychain, still named
johnjacobjingleheimerschmidt in
john's new home directory. Navigate to
Macintosh HD → Users
→ john →
Library →
Keychains and rename the file
johnjacobjingleheimerschmidt to
john.
Figure 6. Renaming johnjacobjingleheimerschmid's keychain to john
Speaking of ownership, while john
now has a new home directory, if you took a close look at the
permissions, you'd see that he still
doesn't actually own the directory or anything in it
— everything's owned by the root user (since
he requested the duplication, he owns the files). To fix the
permissions, launch the Terminal [Hack #48]
(Applications → Utilities
→ Terminal) and use the
chown
command, like so:
[HappyMac:/Users] root# chown -R john.staff john
[HappyMac:/Users] root# ls -l
total 0
drwxrwx--- 4 root admin 136 Feb 6 23:07 Deleted Users
drwxrwxrwt 3 root wheel 102 Jul 13 2002 Shared
drwxr-xr-x 11 john staff 374 Feb 6 23:08 john
drwxr-xr-x 11 johnjaco staff 374 Feb 5 17:48 &carriage;
johnjacobjingleheimerschmidt
Notice that the john directory is now owned by
the john account and is in the right (staff)
group.
TIP
You'd think you could do this via the Get Info
dialog box. It does, after all, allow you to change permissions on a
folder and "Apply to enclosed items . . .
", but it just doesn't work as
expected. You can apply some changes recursively to the contents of a
folder, but you can't change the ownership in this
way.
Log out as
the root user and log back in again as yourself. Disable the root [Hack #50]
user and you're done.
Give the new john account a try by logging in and fiddling about.
When you're sure all's as it should
be, go ahead and delete the old johnjacobjingleheimerschmidt account
and alter john's Name (System Preferences →
Accounts → Edit User) as appropriate — in this
example, we dropped the II bit.
Deleting an Account
Deleting an
account under Mac OS X is simple using
the Accounts System Preferences panel (System Preferences →
Accounts → Delete User). This will remove the account and
disable the associated home directory.
Deleted accounts, however, are gone but not completely forgotten. If
you take a moment to actually read the confirmation dialog, you'll learn that the
contents of the now-deleted account's home directory
are archived as a disk image in Macintosh HD
→ Users →
Deleted Users.
Figure 7. Confirming account deletion
When and if you're ready to permanently delete the
contents of an archived home directory, simply drag its disk image to the Trash.
Figure 8. A deleted account's archived home directory
