Comments on: The Meaning of 'su' https://pthree.org/2009/12/31/the-meaning-of-su/ Linux. GNU. Freedom. Fri, 01 Dec 2017 15:29:07 +0000 hourly 1 https://wordpress.org/?v=5.0-alpha-42199 By: The Meaning of ‘su’ | شخصی https://pthree.org/2009/12/31/the-meaning-of-su/#comment-129370 Fri, 09 Aug 2013 02:40:20 +0000 http://pthree.org/?p=1213#comment-129370 […] The Meaning of ‘su’ […]

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By: Kevin Burke https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124720 Fri, 12 Apr 2013 14:47:22 +0000 http://pthree.org/?p=1213#comment-124720 Brevity is always a good thing.

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By: Owain https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124288 Fri, 01 Mar 2013 20:15:48 +0000 http://pthree.org/?p=1213#comment-124288 "But again, it really doesn’t matter what it stands for, does it? What matters is how you use it."

Totally. It could be called 'bananajuice', and it would still function in the same way. Similarly, knowing the origin of sed, grep and tar have little impact on actual usage, despite them now being symbolic of how far computing has developed. (The benefit of brevity with two-letter commands over slow connections is also something consigned to history!)

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By: Jestin Joy https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124276 Mon, 25 Feb 2013 14:52:54 +0000 http://pthree.org/?p=1213#comment-124276 For a moment I thought that what I taught all these years to students was wrong. Dennis Ritchie saved my day 🙂

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By: Simon Arthur https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124275 Mon, 25 Feb 2013 13:51:49 +0000 http://pthree.org/?p=1213#comment-124275 I love how easy it is to overflow the 100 character buffer when entering the password.

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By: Luffy Ke https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124274 Mon, 25 Feb 2013 11:02:12 +0000 http://pthree.org/?p=1213#comment-124274 sudo echo 'Interesting reading'

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By: Jan de Vos https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124273 Mon, 25 Feb 2013 10:47:17 +0000 http://pthree.org/?p=1213#comment-124273 Surely the wat to start a subshell is by just executing 'sh'? The purpose of su is to make sure you are running as a specific user, so 'Set Uid' would be the most logical interpretation...,

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By: Tri https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124272 Mon, 25 Feb 2013 06:36:19 +0000 http://pthree.org/?p=1213#comment-124272 Unix history is always an interesting read!

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By: Marco https://pthree.org/2009/12/31/the-meaning-of-su/#comment-124271 Mon, 25 Feb 2013 05:34:43 +0000 http://pthree.org/?p=1213#comment-124271 I think there's a bug on the code.. to label badpw fallbacks to ok:, so if the getpw doesn't return a correct passwd, setuid(0) will be called >.<

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By: Why, fedora WHY!!!??? - Page 4 - Overclock.net - Overclocking.net https://pthree.org/2009/12/31/the-meaning-of-su/#comment-115525 Wed, 09 Mar 2011 19:40:22 +0000 http://pthree.org/?p=1213#comment-115525 [...] with my built in console/python terminal, build tools, tabs, and sessions for anything. Noooooo http://pthree.org/2009/12/31/the-meaning-of-su/ It goes way back to the original Unix code and meanings. Originally SU was SuperUser and not [...]

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By: jonkx https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110933 Mon, 31 May 2010 17:22:42 +0000 http://pthree.org/?p=1213#comment-110933 I worked with the Unix OS from the early 1980's (at first we ran early versions on a DEC PDP-11) until 1992. Starting in 1992, I did contract work on proprietary versions based on SVR4.

It was just easier to say the initials "S U" or "super-user" than to say "switch user" or "substitute user". To insist on correctness, whether authoritarian, historical or otherwise seems petty.

Depending on the options used, su can be used to switch user, substitute user or become "super user". Success depends on knowledge of the appropriate password. "sudo" on the other hand may allow one to become any other user (depending on the configuration of sudo and being a "sodoer") knowing only the login password.

On the systems I have used, a sudoer can become root ("super user") using this shell command at a terminal:

sudo su - root

and responding to the prompt with the login password used to sign in the current user.

I think it is important to point out that you cannot become "super user" or root from a shell with the su command alone unless there is a root password and that password is entered at the prompt.

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By: The (C) Gentoo User https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110757 Wed, 17 Mar 2010 16:58:53 +0000 http://pthree.org/?p=1213#comment-110757 Please fix the code. It does not compile with the latest GCC. Thanks.

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By: Meanwhile in Gotham City ← pseudopost.org https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110737 Sun, 07 Mar 2010 03:33:40 +0000 http://pthree.org/?p=1213#comment-110737 [...] Shared Aaron Toponce : The Meaning of ’su’. [...]

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By: NetStorming » El significado de “su” https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110647 Sun, 10 Jan 2010 04:40:48 +0000 http://pthree.org/?p=1213#comment-110647 [...] Al parecer, Aaron Toponce lo ha hecho en muchas oportunidades, llegando al punto de escribir un post sobre el significado de su. En el mismo comenta los distintos descubrimientos que evidenciaban diferentes significados para [...]

[WORDPRESS HASHCASH] The comment's actual post text did not contain your blog url (http://pthree.org/2009/12/31/the-meaning-of-su) and so is spam.

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By: Capt Caveman https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110580 Sun, 03 Jan 2010 03:48:44 +0000 http://pthree.org/?p=1213#comment-110580 Back in the mid 70's when I learning to program my professor said su stood for super user and it that gave you the power to destroy an entire computer system with a single command.

[WORDPRESS HASHCASH] The poster sent us '0 which is not a hashcash value.

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By: Garry Parker https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110577 Fri, 01 Jan 2010 20:16:37 +0000 http://pthree.org/?p=1213#comment-110577 Aaron, you've got a point there! The more I think about, the more I tend to agree with you. If it was only used to become super-user, it's possible that's what the name originally meant. Perhaps later when more features were added, the definition changed. I've been using Unix since the late 80s and like you I've always heard that su meant super-user.

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By: Aaron https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110576 Fri, 01 Jan 2010 08:00:38 +0000 http://pthree.org/?p=1213#comment-110576 @Garry Parker I would agree with you, except the code only allows switching to the root user. Switching to any other user wasn't possible like it is now. But again, it really doesn't matter what it stands for, does it? What matters is how you use it.

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By: Twitted by mehulved https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110575 Fri, 01 Jan 2010 03:28:19 +0000 http://pthree.org/?p=1213#comment-110575 [...] This post was Twitted by mehulved [...]

[WORDPRESS HASHCASH] The comment's server IP (94.23.51.159) doesn't match the comment's URL host IP (87.98.139.183) and so is spam.

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By: Links 1/1/2010: Many New GNU/Linux Releases, Ubuntu Tweak 0.5 | Boycott Novell https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110574 Fri, 01 Jan 2010 03:07:39 +0000 http://pthree.org/?p=1213#comment-110574 [...] The Meaning of ’su’ [...]

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By: Vadim P. https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110573 Fri, 01 Jan 2010 00:49:45 +0000 http://pthree.org/?p=1213#comment-110573 Interesting read.

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By: Garry Parker https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110572 Thu, 31 Dec 2009 23:02:04 +0000 http://pthree.org/?p=1213#comment-110572 I'm looking at volume 1 of the "UNIX Programmer's Manual, Revised and Expanded Version", published by Bell Laboratories, copywrite 1983, 1979 and according to this source, su means "substitue user id". Of course the C code you posted above predates that, but I think you might be misinterpreting the comment. The comment is merely saying the "substitute user id" command is used to become the "super-user" AKA root user.

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By: BUGabundo https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110571 Thu, 31 Dec 2009 19:45:40 +0000 http://pthree.org/?p=1213#comment-110571 Thanks for sharing.
its a fun and nice reading
[[]]

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By: Joseph Scott https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110570 Thu, 31 Dec 2009 18:35:33 +0000 http://pthree.org/?p=1213#comment-110570 The FreeBSD man page - http://www.freebsd.org/cgi/man.cgi?query=su&apropos=0&sektion=0&manpath=FreeBSD+8.0-RELEASE&format=html - calls it "su -- substitute user identity".

The history section at the bottom mentions:

"A su command appeared in Version 1 AT&T UNIX."

The man page for V3 - http://minnie.tuhs.org/UnixTree/V3/usr/man/man8/su.8.html - (dated 1/20/73) says:

"su -- become privileged user"

If there was a su command in V1 (which sounds likely) I wonder if it only supported switching to root. Perhaps the more generalized approach didn't come until later.

There are some other interesting early Unix history bits in this paper - http://www.usenix.org/events/usenix09/tech/full_papers/toomey/toomey.pdf - not directly related to su, but an interesting read.

Oh! More searching turned up this as well - http://code.google.com/p/unix-jun72/ - the scanned in codes from this - http://www.bitsavers.org/pdf/bellLabs/unix/PreliminaryUnixImplementationDocument_Jun72.pdf

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By: Aaron https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110569 Thu, 31 Dec 2009 17:21:29 +0000 http://pthree.org/?p=1213#comment-110569 @Jensen I have no idea, but Ken Thompson said himself that if he were to rewrite the C programming language, creat() would be create().

@kragil You didn't read the post, at least not all the way through, did you? You might want to do that before commenting.

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By: kragil https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110568 Thu, 31 Dec 2009 16:08:17 +0000 http://pthree.org/?p=1213#comment-110568 At first I thought it meant "super user", but then I was told it was "switch user" .. are you 100% certain?

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By: Florob https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110567 Thu, 31 Dec 2009 16:05:27 +0000 http://pthree.org/?p=1213#comment-110567 Just FWIW, I have also heard su stands for set/switch uid.
Definitely one of the long standing questions with the most possible answers you discussed there 😉

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By: Jensen https://pthree.org/2009/12/31/the-meaning-of-su/#comment-110566 Thu, 31 Dec 2009 15:48:10 +0000 http://pthree.org/?p=1213#comment-110566 OK, I am curious now. Why does the creat() command in C lacks an "e"?

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