"S" mode for file permission?

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"S" mode for file permission?

Gary Aitken
I'm having to fix some permissions in some ruby file hierarchies, and
came across one with a 'S' for group (note, not 's').  man chmod doesn't
mention 'S', although it does mention 'X'.  Can someone tell me what 'S'
represents, and why an attempt to chmod g+s results in a 'S'?  Also, why
it would be set that way for a particular directory when all others above
it have 's'?

.../rvm/gems/ruby-2.6.6/extensions$ ls -l
drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux

.../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g+s  x86_64-linux/
.../rvm/gems/ruby-2.6.6/extensions$ ls -l
drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux

.../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g-S  x86_64-linux/
chmod: invalid mode: ‘g-S’

.../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g-s  x86_64-linux/
.../rvm/gems/ruby-2.6.6/extensions$ ls -l
drwxrw-r-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux

.../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g+s  x86_64-linux/
.../rvm/gems/ruby-2.6.6/extensions$ ls -l
drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux

Thanks,

Gary

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Re: "S" mode for file permission?

Jose I Diaz Bardales


On 12/12/20 12:41 PM, Gary Aitken wrote:

> I'm having to fix some permissions in some ruby file hierarchies, and
> came across one with a 'S' for group (note, not 's').  man chmod doesn't
> mention 'S', although it does mention 'X'.  Can someone tell me what 'S'
> represents, and why an attempt to chmod g+s results in a 'S'?  Also, why
> it would be set that way for a particular directory when all others above
> it have 's'?
>
> .../rvm/gems/ruby-2.6.6/extensions$ ls -l
> drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux
>
> .../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g+s  x86_64-linux/
> .../rvm/gems/ruby-2.6.6/extensions$ ls -l
> drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux
>
> .../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g-S  x86_64-linux/
> chmod: invalid mode: ‘g-S’
>
> .../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g-s  x86_64-linux/
> .../rvm/gems/ruby-2.6.6/extensions$ ls -l
> drwxrw-r-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux
>
> .../rvm/gems/ruby-2.6.6/extensions$ sudo chmod g+s  x86_64-linux/
> .../rvm/gems/ruby-2.6.6/extensions$ ls -l
> drwxrwSr-x 3 rubes rubes 4096 Dec  2 05:20 x86_64-linux
>
> Thanks,
>
> Gary
>

If I remember correctly s is to set the group id on a file or directory
in other words the file can executed on behalf of the group.

The "s" is for directories and "S" for files.



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Re: "S" mode for file permission?

ubuntu-users mailing list
On Sat, 12 Dec 2020 15:30:59 -0500, Jose I Diaz Bardales wrote:
>If I remember correctly s is to set the group id on a file or
>directory in other words the file can executed on behalf of the group.
>
>The "s" is for directories and "S" for files.

No! Google is your friend!

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Re: "S" mode for file permission?

Jose I Diaz Bardales


On 12/12/20 3:46 PM, Ralf Mardorf via ubuntu-users wrote:
> On Sat, 12 Dec 2020 15:30:59 -0500, Jose I Diaz Bardales wrote:
>> If I remember correctly s is to set the group id on a file or
>> directory in other words the file can executed on behalf of the group.
>>
>> The "s" is for directories and "S" for files.
>
> No! Google is your friend!
>

I knew memory will fail. Ralf is right so if the file does not havean
execute (x) permission when you set the group id you will see an
uppercase "S" instead of a lowercase "s"  :-)

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Re: "S" mode for file permission?

Peter Flynn
In reply to this post by Gary Aitken
On 12/12/2020 17:41, Gary Aitken wrote:
> I'm having to fix some permissions in some ruby file hierarchies, and
> came across one with a 'S' for group (note, not 's').  man chmod doesn't
> mention 'S', although it does mention 'X'.  Can someone tell me what 'S'
> represents, and why an attempt to chmod g+s results in a 'S'?  Also, why
> it would be set that way for a particular directory when all others above
> it have 's'?

S(s) sets the Sticky Bit. https://en.wikipedia.org/wiki/Sticky_bit

Peter

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Re: "S" mode for file permission?

Tom H-4
In reply to this post by Gary Aitken
On Sat, Dec 12, 2020 at 6:46 PM Gary Aitken <[hidden email]> wrote:
>
> I'm having to fix some permissions in some ruby file hierarchies,
> and came across one with a 'S' for group (note, not 's'). man
> chmod doesn't mention 'S', although it does mention 'X'. Can
> someone tell me what 'S' represents, and why an attempt to chmod
> g+s results in a 'S'? Also, why it would be set that way for a
> particular directory when all others above it have 's'?

"rws" means that the sgid bit is set.

"rwS" means that the sgid bit is set and the file's not executable for
the group.

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Re: "S" mode for file permission?

Tom H-4
In reply to this post by Peter Flynn
On Sat, Dec 12, 2020 at 10:09 PM Peter Flynn <[hidden email]>
wrote:
> On 12/12/2020 17:41, Gary Aitken wrote:
>> I'm having to fix some permissions in some ruby file hierarchies,
>> and came across one with a 'S' for group (note, not 's'). man
>> chmod doesn't mention 'S', although it does mention 'X'. Can
>> someone tell me what 'S' represents, and why an attempt to chmod
>> g+s results in a 'S'?  Also, why it would be set that way for a
>> particular directory when all others above it have 's'?
>
> S(s) sets the Sticky Bit.

The sticky bit's set with "s". (Given that the kernel disregards the
sticky bit for files, "S" doesn't make sense.)

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Re: "S" mode for file permission?

Oleg Cherkasov
In reply to this post by Peter Flynn
On 12.12.2020 22:08, Peter Flynn wrote:
> On 12/12/2020 17:41, Gary Aitken wrote:
>> I'm having to fix some permissions in some ruby file hierarchies, and
>> came across one with a 'S' for group (note, not 's').  man chmod doesn't
>> mention 'S', although it does mention 'X'.  Can someone tell me what 'S'
>> represents, and why an attempt to chmod g+s results in a 'S'?  Also, why
>> it would be set that way for a particular directory when all others above
>> it have 's'?
>
> S(s) sets the Sticky Bit. https://en.wikipedia.org/wiki/Sticky_bit

I always thought the Sticky Bit is rather T(t).  The mentioned wikipage
confirms it, scroll to examples at the bottom.

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Re: "S" mode for file permission?

Sheemon Lists
Sticky bit is indeed ;t;,  Print the numeric fields to see the gymnastics taken in the directory listings and file perms.

BTW, the first ever software patent was issued to Dennis Ritchie (Bell Labs) for the invention of the suid bit.
Years later, Micro$oft tried to outdo that by patenting the concept of a bit.

The first trivia item above is true AFAIK.  The second was a rumor I believe to be false.  Even M$ cannot be this dumb.

Don't Google - Read the source.

Simon


On Mon, Dec 14, 2020 at 5:28 AM Oleg Cherkasov <[hidden email]> wrote:
On 12.12.2020 22:08, Peter Flynn wrote:
> On 12/12/2020 17:41, Gary Aitken wrote:
>> I'm having to fix some permissions in some ruby file hierarchies, and
>> came across one with a 'S' for group (note, not 's').  man chmod doesn't
>> mention 'S', although it does mention 'X'.  Can someone tell me what 'S'
>> represents, and why an attempt to chmod g+s results in a 'S'?  Also, why
>> it would be set that way for a particular directory when all others above
>> it have 's'?
>
> S(s) sets the Sticky Bit. https://en.wikipedia.org/wiki/Sticky_bit

I always thought the Sticky Bit is rather T(t).  The mentioned wikipage
confirms it, scroll to examples at the bottom.

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Re: "S" mode for file permission?

Colin Watson
On Mon, Dec 14, 2020 at 10:29:35AM -0500, Sheemon Lists wrote:
> BTW, the first ever software patent was issued to Dennis Ritchie (Bell
> Labs) for the invention of the suid bit.
> Years later, Micro$oft tried to outdo that by patenting the concept of a
> bit.
>
> The first trivia item above is true AFAIK.  The second was a rumor I
> believe to be false.  Even M$ cannot be this dumb.

While Ritchie was indeed granted such a patent in 1979, a cursory
Wikipedia check finds at least one earlier example of a software patent
(https://worldwide.espacenet.com/patent/search/family/010129789/publication/GB1039141A?q=pn%3DGB1039141),
granted in 1966 and thus I believe expired in 1986.  Since the abstract
says "The Specification is confined to a description of the programming
method [...] which is applicable to any general-purpose digital
computer", it seems clear that this can only be a software patent and
not a patent on the physical hardware.

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