single user mode, what is it good for

[biohazard6969]

hey, justt a general question, i hear references to single user mode and fsck all the time, but i was just wondering if there is anything else that single user mode is good for, as well i'd also like to know wat keys to hold down on startup to get different results, i.e. ?S for single user, i think its space bar, or mouse click to force an eject, i'm sure theres others

 

[mkrishnan]

Well, for the first part of your question, the basic reason single user mode exists in MacOS, or Linux, or anything, is that when the full OS loads up, it starts a large number of processes that put files and disk space in use. These files-in-use prevent the OS from being able to safely run some utilities that are meant to analyze and fix problems, because changing a file while it's being used is, well, like trying to change somebody's shoes for them while they're running. You can do it, but you have to tackle them.

 

[Westside guy]

Single user mode gives you complete control over a machine. On an OS X machine you can change/add/remove netinfo database entries, for one thing. This means you can make a non-admin account into an admin account, add new accounts, change boot records, and so on. You can clean out the entire file system. Etc. etc. etc...

That's why there's an adage that computer security is worthless unless you also have physical security (basically it's why server rooms are locked). If someone can get to your computer, they can break pretty much any level of security as long as they have enough time.

 

[biohazard6969]

ok, so is this a bad thing, are you sxaying taht anyone who knows how to use single user mode can get at anything in my computer? is there nothing to protect this at all?

and how do u do some of the other things you said

 

[wordmunger]

ok, so is this a bad thing, are you sxaying taht anyone who knows how to use single user mode can get at anything in my computer? is there nothing to protect this at all?

and how do u do some of the other things you said

I'm not sure about single user mode, but I'm fairly certain the only way to protect your data when others have physical access to your computer is to use filevault or some other sort of encryption.

 

[MacsRgr8]

In general:
He who has physical access to computer, should be able become "the owner", one way or the other. There are several ways of making this more difficult (OpenFirmware password etc.)

Wether this is good or not, is debatable.

Panther's FileVault is there to protect the data of a specific user, especially in the case of eh.... "change of ownership" (i.e. steeling). But it cannot protect it from deletion.