2

In the POSIX Definitions there is specific section 3.424, User Database, which defines what information should be related to each user ID. However through out the document, I couldn't find (at least not via simple Ctrl+f search) mention of either root nor any of the typical system usernames, such as syslog, bin, daemon, nobody, sys. There doesn't seem to be mention of these in newgrp utility definitions either, to which the 3.424 refers.

This begs the question: does POSIX require existence of certain system-level usernames or UIDs ? Is root user even required to be root, or is it theoretically possible to have POSIX-compliant system where the most powerful system account is not called root or has non-zero UID?

Improve this question
4
  • 1
    POSIX explicitly does not standardize system utilities and administration part. Commented Jan 16, 2019 at 11:42
  • @GiacomoCatenazzi Any source for that statement ? I am curious to which extent then POSIX does limit administration part. But utilities and interfaces are in fact standardized, at least basic utilities such as cat, /bin/sh, etc Commented Jan 16, 2019 at 11:48
  • Now I do not find it explicitly (but the first paragraph of the standard tell us that it is mostly about shell utilities and API for programmers and users (but not for administration). In fact you do not find very common "su, passwd, mount" as utilities. "init" was cited only once (and just for zombies handling, not the system initialization) Commented Jan 16, 2019 at 12:54
  • Note: you linked the old POSIX. [It doesn't matter much on this question, but I want to put it into your attention] Commented Jan 16, 2019 at 12:55

1 Answer 1

Reset to default
3

That is a very good question. To which the simple answer would be no.

There is no guarantee, and you could even rename root to toto.

But your system would probably be unstable, since a lot of services and functions depend on certain usernames, typically, root.

Improve this answer
2
  • That is a very tempting username, toto , I might consider using it in future :) What about the UID itself ? Would these be "set in stone" so to speak ? Commented Jan 16, 2019 at 11:49
  • I agree, thinking to get toto's privileges. For the UID, 0 is the only one that is really always the admin user. The up to 99 are usually reserved. Users used to start at 500, and now at 1000. And the link here : linfo.org/uid.html Commented Jan 16, 2019 at 11:58

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.