Origin of 'root' account

Question

What's the origin of root account? Where did it come from and why is it called root anyway?

_{(Originally asked by @lizztheblizz on Twitter.)}

I believe it to refer to 'the root of all evil' as sometimes my computer does do devilish things on its own accord. — , Nov 10 '15 at 14:15

score 50 · Accepted Answer · edited Jul 03 '12 at 22:41

50

The original home directory of the root user was the root of the filesystem / (http://minnie.tuhs.org/cgi-bin/utree.pl?file=V5/etc/passwd). I think the user was indeed named after that directory. But why 'root' and not 'start' or 'origin' or something else? Well, before Ken Thompson and Dennis Ritchie wrote UNIX, they were (also at Bell Labs) developing Multics. If you take a look at Multics history, you will find that ROOT existed there too (http://web.mit.edu/multics-history/source/Multics_Internet_Server/Multics_mdds.html). So the name must come from Multics.

edited Jul 03 '12 at 22:41

Keith Thompson

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answered Feb 24 '11 at 14:35

Tom Van Looy

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I just looked at the Multics documents you linked to. They refer to the root directory (and the root volume), but there's no reference to a root *user*. – Keith Thompson Jul 03 '12 at 22:47
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There is a root user seen in mdd003.compout if you look at what appears to be a file list there is clearly a root user just as seen in an "ls -l" command on Unix. – HackSlash Jan 22 '18 at 16:48

score 23 · Answer 2 · answered Feb 24 '11 at 14:24

According to Linux Info, the origin of the name may have come from file system layout / permissions:

The use of the term root for the all-powerful administrative user may have arisen from the fact that root is the only account having write permissions (i.e., permission to modify files) in the root directory. The root directory, in turn, takes its name from the fact that the filesystems (i.e., the entire hierarchy of directories that is used to organize files) in Unix-like operating systems have been designed with a tree-like (although inverted) structure in which all directories branch off from a single directory that is analogous to the root of a tree.

Origin of 'root' account

2 Answers2