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Permissions for an entire PARTITION

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  Permissions for an entire PARTITION Richard Owlett <rowlett@cloud85.net> - 2016-10-25 17:40 +0200
    Re: Permissions for an entire PARTITION Greg Wooledge <wooledg@eeg.ccf.org> - 2016-10-25 17:50 +0200
      Re: Permissions for an entire PARTITION <tomas@tuxteam.de> - 2016-10-25 18:10 +0200
      Re: Permissions for an entire PARTITION Richard Owlett <rowlett@cloud85.net> - 2016-10-25 18:40 +0200
        Re: Permissions for an entire PARTITION Greg Wooledge <wooledg@eeg.ccf.org> - 2016-10-25 18:50 +0200
          Re: Permissions for an entire PARTITION Richard Owlett <rowlett@cloud85.net> - 2016-10-28 17:30 +0200
            Re: Permissions for an entire PARTITION Greg Wooledge <wooledg@eeg.ccf.org> - 2016-10-28 17:50 +0200
            Re: Permissions for an entire PARTITION Jörg-Volker Peetz <jvpeetz@web.de> - 2016-10-28 21:40 +0200
              EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Richard Owlett <rowlett@cloud85.net> - 2016-10-28 22:50 +0200
                Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] "John L. Ries" <jries@salford-systems.com> - 2016-10-28 23:10 +0200
                Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-29 00:20 +0200
                  Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Richard Owlett <rowlett@cloud85.net> - 2016-10-29 01:40 +0200
                    Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Reco <recoverym4n@gmail.com> - 2016-10-29 11:20 +0200
                      Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] rhkramer@gmail.com - 2016-10-29 14:20 +0200
                        Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Reco <recoverym4n@gmail.com> - 2016-10-29 15:00 +0200
                          Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-29 16:10 +0200
                            Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Reco <recoverym4n@gmail.com> - 2016-10-29 17:50 +0200
                              Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-29 20:20 +0200
                                Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Reco <recoverym4n@gmail.com> - 2016-10-29 22:30 +0200
                                  Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-30 00:50 +0200
                                    Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Reco <recoverym4n@gmail.com> - 2016-10-30 10:30 +0100
                                      Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-30 14:00 +0100
                                        Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] rhkramer@gmail.com - 2016-10-30 14:20 +0100
                                          Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-30 18:10 +0100
                          Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] rhkramer@gmail.com - 2016-10-29 21:30 +0200
                            Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-29 22:00 +0200
                              Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] rhkramer@gmail.com - 2016-10-29 22:30 +0200
                                Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Brian <ad44@cityscape.co.uk> - 2016-10-30 01:10 +0200
                                  Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] rhkramer@gmail.com - 2016-10-30 01:20 +0200
                                    Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] Lisi Reisz <lisi.reisz@gmail.com> - 2016-10-30 13:00 +0100
                    Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION] David Wright <deblis@lionunicorn.co.uk> - 2016-10-31 02:30 +0100
            Re: Permissions for an entire PARTITION Jochen Spieker <ml@well-adjusted.de> - 2016-10-29 15:30 +0200
        Re: Permissions for an entire PARTITION Jochen Spieker <ml@well-adjusted.de> - 2016-10-25 19:40 +0200
        Re: Permissions for an entire PARTITION <tomas@tuxteam.de> - 2016-10-26 10:20 +0200
          Re: Permissions for an entire PARTITION rhkramer@gmail.com - 2016-10-26 13:20 +0200
            Re: Permissions for an entire PARTITION Greg Wooledge <wooledg@eeg.ccf.org> - 2016-10-26 14:30 +0200
              Re: Permissions for an entire PARTITION <tomas@tuxteam.de> - 2016-10-26 14:50 +0200
              Re: Permissions for an entire PARTITION Tixy <tixy@yxit.co.uk> - 2016-10-27 07:50 +0200

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#174020 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

	Hi.

On Sat, 29 Oct 2016 23:49:17 +0100
Brian <ad44@cityscape.co.uk> wrote:

> On Sat 29 Oct 2016 at 23:23:52 +0300, Reco wrote:
> 
> > On Sat, 29 Oct 2016 19:15:53 +0100
> > Brian <ad44@cityscape.co.uk> wrote:
> > 
> > > I wish you had addressed the "equal exposure" question. Desktops are not
> > > the only environments in town. Leaving non-policykit users out in the
> > > cold is not an option.
> > 
> > True, that does not look good at all. But why bother listing udisks2
> > which is using PolicyKit then?
> 
> In the light of previous points I think there is a non-sequiteur in
> there somwhere.

Nope, it was only an observation. 


> > > A page on pmount is a little harder because it is a moving target.
> > 
> > I honestly lost you here. oldstable, stable, testing and even sid have
> > the same upstream version of pmount - 0.9.23, dated 2010.
> 
> They do indeed. Six years. Do you get the feeling it is getting on for
> unmaintained. (And a wiki page with HAL on it! I ask you). But software
> changes. Then wiki pages change. 

Why bother with feelings then you have packages.qa.debian.org?
It plainly states that:

The current maintainer is looking for someone who can take over
maintenance of this package.


I'm still don't get it how does it make pmount a 'moving target'. It's
the direct opposite of it IMO.

> > > Mounting and unmounting are not really a problem. Users and root can
> > > easily do these. But, as far as I can see, only someone with root
> > > privileges can use dd, cfdisk, fdisk and mkfs.vfat with a removable
> > > device. I'd like to be wrong.
> > 
> > This is a common myth that I'll debunk gladly.
> > 
> > Image copying (dd or any other tool) merely requires ability to write
> > to a block device. Such permissions on removable media should be
> > provided to any current console user by logind (or ConsoleKit if we
> > still need to think about wheezy), or a good old-fashioned
> > 'floppy' (any group name will do) group and a custom udev rule (as of
> > jessie).
> > 
> > Creating any filesystem on a removable media's partition merely requires
> > the same.
> 
> Since you wrote this, hundreds of people using GNOME have popped a USB
> stick into their machines and typed
> 
>   dd if=/dev/zero of=/dev/<somewhere>
> 
> Those who didn't get
> 
>   dd: failed to open 'dev/<somewhere>'
> 
> will be along soon to report success and explain why.

#788662, comment 28 to be precise. I'm too lazy to discover that secret
'D-Bus interfaces provided by udisks2' personally.


> The floppy group + a udev rule is a Wheezy thing. Not suitable for a
> wiki relating to a current Debian.

Just because it looks obsolete does not mean it does not work. Still,
if you need to do it FreeDesktop way, you'll need an udev rule like
this:

ACTION=="add", ENV{ID_BUS}=="usb", KERNEL=="sd*", TAG+="uaccess"

Reco

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#174027 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sun 30 Oct 2016 at 12:22:43 +0300, Reco wrote:

> On Sat, 29 Oct 2016 23:49:17 +0100
> Brian <ad44@cityscape.co.uk> wrote:
> 
> > They do indeed. Six years. Do you get the feeling it is getting on for
> > unmaintained. (And a wiki page with HAL on it! I ask you). But software
> > changes. Then wiki pages change. 
> 
> Why bother with feelings then you have packages.qa.debian.org?
> It plainly states that:
> 
> The current maintainer is looking for someone who can take over
> maintenance of this package.
> 
> I'm still don't get it how does it make pmount a 'moving target'. It's
> the direct opposite of it IMO.

Software changes over time (features etc), necessitating a review and
possible rewrite of parts of the documentation.

> > Since you wrote this, hundreds of people using GNOME have popped a USB
> > stick into their machines and typed
> > 
> >   dd if=/dev/zero of=/dev/<somewhere>
> > 
> > Those who didn't get
> > 
> >   dd: failed to open 'dev/<somewhere>'
> > 
> > will be along soon to report success and explain why.
> 
> #788662, comment 28 to be precise. I'm too lazy to discover that secret
> 'D-Bus interfaces provided by udisks2' personally.

#781495.

> > The floppy group + a udev rule is a Wheezy thing. Not suitable for a
> > wiki relating to a current Debian.
> 
> Just because it looks obsolete does not mean it does not work. Still,
> if you need to do it FreeDesktop way, you'll need an udev rule like
> this:
> 
> ACTION=="add", ENV{ID_BUS}=="usb", KERNEL=="sd*", TAG+="uaccess"

A user without privileges to partition a USB stick or write to its MBR
(which is the case on jessie and later) won't be able to do either of
these.

There are some good things which have come out of this discussion. To
use cfdisk, fdisk, dd, mkfs.vfat and grub-install a user has to be
root. Being able to mount as non-root is neither here nor there on
jessie and stretch for the purpose of installing GRUB, so references to
pmount etc can go.

-- 
Brian.

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#174028 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sunday, October 30, 2016 08:54:45 AM Brian wrote:
> There are some good things which have come out of this discussion. To
> use cfdisk, fdisk, dd, mkfs.vfat and grub-install a user has to be
> root. Being able to mount as non-root is neither here nor there on
> jessie and stretch for the purpose of installing GRUB, so references to
> pmount etc can go.


Are you the maintainer or an author on that wiki page (the one that has been 
discussed here)?

If so, have you considered splitting the page into two pages, one for Wheezy 
(or pre-Jessie) and one for Jessie?  The intent would be to keep valid 
information for Wheezy for people that might still need it.

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#174050 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sun 30 Oct 2016 at 09:19:04 -0400, rhkramer@gmail.com wrote:

> On Sunday, October 30, 2016 08:54:45 AM Brian wrote:
> > There are some good things which have come out of this discussion. To
> > use cfdisk, fdisk, dd, mkfs.vfat and grub-install a user has to be
> > root. Being able to mount as non-root is neither here nor there on
> > jessie and stretch for the purpose of installing GRUB, so references to
> > pmount etc can go.
> 
> Are you the maintainer or an author on that wiki page (the one that has been 
> discussed here)?

I don't think wiki pages have maintainers as such, just people who take
an interest and provide additional information, corrections and updates.
Yes, I am the originator of the page, but it is everyone's page.

> If so, have you considered splitting the page into two pages, one for Wheezy 
> (or pre-Jessie) and one for Jessie?  The intent would be to keep valid 
> information for Wheezy for people that might still need it.

As it stands, anyone using pre-Jessie (that's a good way you found of
putting it) could follow the instructions on the page and carry them out
without needing root access. It should be possible to accomodate pre-
and post-Jessie users on the same page by making the requirements for
the different distributions clearer. After all, the commands to use are
practically identical. A small extra section would do it.

--  
Brian.

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#173998 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Saturday, October 29, 2016 08:54:59 AM Reco wrote:
> On Sat, 29 Oct 2016 08:16:18 -0400
> rhkramer@gmail.com wrote:

> > I'm not the OP or anybody that has participated in this thread so far.
> 
> [1] tells me otherwise, for the 'participation' part. I take it that
> this e-mail I'm replying to is shared among several people, then?

Oops, sorry, you're right--somehow I forgot all about that.

> I believe you're missing the point here. The page in question is not
> supposed to provide information on mounting anything as a *key piece*
> in the first place due to very nature of the topic the page describes.
> 
> But since such information is in there for some reason, and it's
> covering *both* mounting and unmounting in a compact enough form - it
> can be used as an example for mounting and unmounting also.

If I say anything, I'll just be belaboring the point further, so I won't. Or, 
I will, I was only trying to support the OP who said there was nothing of 
significance (or some similar word) (re: pmount) on that page.

Now I'll just hide my head in the sand ;-)

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#174000 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sat 29 Oct 2016 at 15:28:14 -0400, rhkramer@gmail.com wrote:

> On Saturday, October 29, 2016 08:54:59 AM Reco wrote:
> > On Sat, 29 Oct 2016 08:16:18 -0400
> > rhkramer@gmail.com wrote:
> 
> > > I'm not the OP or anybody that has participated in this thread so far.
> > 
> > [1] tells me otherwise, for the 'participation' part. I take it that
> > this e-mail I'm replying to is shared among several people, then?
> 
> Oops, sorry, you're right--somehow I forgot all about that.
> 
> > I believe you're missing the point here. The page in question is not
> > supposed to provide information on mounting anything as a *key piece*
> > in the first place due to very nature of the topic the page describes.
> > 
> > But since such information is in there for some reason, and it's
> > covering *both* mounting and unmounting in a compact enough form - it
> > can be used as an example for mounting and unmounting also.
> 
> If I say anything, I'll just be belaboring the point further, so I won't. Or, 
> I will, I was only trying to support the OP who said there was nothing of 

What would you have wanted to see? Please be detailed. The OP is
unlikely to respond, so we are relying on you.

-- 
Brian/

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#174005 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Saturday, October 29, 2016 03:53:21 PM Brian wrote:
> On Sat 29 Oct 2016 at 15:28:14 -0400, rhkramer@gmail.com wrote:
> > On Saturday, October 29, 2016 08:54:59 AM Reco wrote:
> > > On Sat, 29 Oct 2016 08:16:18 -0400
> > > 
> > > rhkramer@gmail.com wrote:
> > > > I'm not the OP or anybody that has participated in this thread so
> > > > far.
> > > 
> > > [1] tells me otherwise, for the 'participation' part. I take it that
> > > this e-mail I'm replying to is shared among several people, then?
> > 
> > Oops, sorry, you're right--somehow I forgot all about that.
> > 
> > > I believe you're missing the point here. The page in question is not
> > > supposed to provide information on mounting anything as a *key piece*
> > > in the first place due to very nature of the topic the page describes.
> > > 
> > > But since such information is in there for some reason, and it's
> > > covering *both* mounting and unmounting in a compact enough form - it
> > > can be used as an example for mounting and unmounting also.
> > 
> > If I say anything, I'll just be belaboring the point further, so I won't.
> > Or, I will, I was only trying to support the OP who said there was
> > nothing of
> 
> What would you have wanted to see? Please be detailed. The OP is
> unlikely to respond, so we are relying on you.

I'll have to think about that--maybe nothing--my first thoughts are that:
   * I agree that page didn't need to go any deeper,
   * but I also agree with the comment the OP made, something like there was 
nothing substantial about pmount on that page--he apparently (or might have) 
tried one of the other two alternatives, and failing that, have asked for more 
help, as he did...

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#174012 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sat 29 Oct 2016 at 16:28:24 -0400, rhkramer@gmail.com wrote:

> On Saturday, October 29, 2016 03:53:21 PM Brian wrote:
> > On Sat 29 Oct 2016 at 15:28:14 -0400, rhkramer@gmail.com wrote:
> > > On Saturday, October 29, 2016 08:54:59 AM Reco wrote:
> > > > On Sat, 29 Oct 2016 08:16:18 -0400
> > > > 
> > > > rhkramer@gmail.com wrote:
> > > > > I'm not the OP or anybody that has participated in this thread so
> > > > > far.
> > > > 
> > > > [1] tells me otherwise, for the 'participation' part. I take it that
> > > > this e-mail I'm replying to is shared among several people, then?
> > > 
> > > Oops, sorry, you're right--somehow I forgot all about that.
> > > 
> > > > I believe you're missing the point here. The page in question is not
> > > > supposed to provide information on mounting anything as a *key piece*
> > > > in the first place due to very nature of the topic the page describes.
> > > > 
> > > > But since such information is in there for some reason, and it's
> > > > covering *both* mounting and unmounting in a compact enough form - it
> > > > can be used as an example for mounting and unmounting also.
> > > 
> > > If I say anything, I'll just be belaboring the point further, so I won't.
> > > Or, I will, I was only trying to support the OP who said there was
> > > nothing of
> > 
> > What would you have wanted to see? Please be detailed. The OP is
> > unlikely to respond, so we are relying on you.
> 
> I'll have to think about that--maybe nothing--my first thoughts are that:
>    * I agree that page didn't need to go any deeper,
>    * but I also agree with the comment the OP made, something like there was 
> nothing substantial about pmount on that page--he apparently (or might have) 
> tried one of the other two alternatives, and failing that, have asked for more 
> help, as he did...

There are very few wiki pages which are so completely self-contained
that one does not have to consult outside sources. It should not be
expected that they be complete in every aspect. Anything not deemed
substantial can be looked up elsewhere, starting, perhaps, with a man
page on a local machine.

What happened to curiosity?

-- 
Brian.
 

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#174013 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Saturday, October 29, 2016 07:00:02 PM Brian wrote:
> What happened to curiosity?

Curiosity is a function of available resources, among them time.

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#174023 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Sunday 30 October 2016 00:19:34 rhkramer@gmail.com wrote:
> On Saturday, October 29, 2016 07:00:02 PM Brian wrote:
> > What happened to curiosity?
>
> Curiosity is a function of available resources, among them time.

The OP says that he has ample time because he is retired and this is his 
retirement occupation.

Lisi

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#174066 — Re: EUREKA!!!! - was [Re: Permissions for an entire PARTITION]

On Fri 28 Oct 2016 at 18:34:10 (-0500), Richard Owlett wrote:
> On 10/28/2016 5:17 PM, Brian wrote:
> >On Fri 28 Oct 2016 at 15:42:27 -0500, Richard Owlett wrote:
> >
> >>Be aware sir that you are the cause of:
> >>    multiple renditions of the "Alleluia Chorus" [courtesy Handle] at >
> >>10^^Bels
> >>    an "innocent"[snicker] senior citizen is about to have many sleepless
> >>nights
> >>    multiple nay-sayers will suffer "EGG ON FACE"  *ROFL* !!!!!
> >>
> >>On 10/28/2016 2:30 PM, Jörg-Volker Peetz wrote:
> >>>Did you take a look at the package pmount?
> >>>I use it to mount external disks.
> >>>It requires no changes to /etc/fstab.
> >>
> >>Just in case you have not perceived this quiet discrete message:
> >>   I have not come across pmount before

https://lists.debian.org/debian-user/2016/01/msg00015.html
made me think that you had read the "valuable page"
https://wiki.debian.org/ManipulatingISOs
which has a section on pmount.

> >Yes you have. It is on the wiki page
> >
> >  https://wiki.debian.org/Installation+Archive+USBStick
> >
> >You read this page about a week or so ago (you told us so) but seemed
> >more concerned about its style rather than its substance.
> >
> 
> *BULL*
> Said page may have included the string "pmount".
> 
> But it gave no useful info!!!!!!!!!!!!!!!!!!!!!

Cheers,
David.

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#173976

[Multipart message — attachments visible in raw view] — view raw

Richard Owlett:
> 
> My original question had (apparently incorrectly assume that partitions
> handled user/group/world permissions in the same manner as file systems.

Even if you found a solution to your problem, this sentence does not
make much sense and I still assume you are confused about a few basics.

Hard disks / SSDs are usualy split into one or more partitions. A
partition is nothing more than a slice of a disk with a given size. It
does not have any permissions except for the permissions of the block
device in /dev that represents it (e.g. /dev/sda1).

Filesystems organize storage space into files and directories. They are
often (but not necessarily) created inside partitions. Since there is
usually a 1:1 relation between partitions and filesystems, many people
use both terms interchangeably but that is technically wrong. You cannot
mount a partition, only a filesystem (which, again, may or may not be
inside a partition).

J.
-- 
Every year I wonder what a tinsel-making machine looks like. And what it
does in summer.
[Agree]   [Disagree]
                 <http://archive.slowlydownward.com/NODATA/data_enter2.html>

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#173849

[Multipart message — attachments visible in raw view] — view raw

Richard Owlett:
> On 10/25/2016 10:40 AM, Greg Wooledge wrote:
>> 
>> The simplest way would be to synchronize your UID across all your
>> installed operating systems.  If your UID is, let's say, 1000 on every
>> system, and the files on the partition are owned by user 1000, then
>> user 1000 (you) will have ownership of the files whenever you mount
>> the partition.
> 
> That sounds like what I want.
> I had previously created a ext2 partition on /dev/sda10 and a label of
> jessie-dvds .
> How do I inform the "WORLD" that it belongs to UID 1000?

chown -R 1000 /

But that is a stupid idea that will probably break your system. Don't do
it.

As far as I understand, you want to be able to read/write/execute files
from one installation in another installation. This is easy as long as
you use the root account. For your regular user (usually UID 1000), this
doesn't make sense on a single installation and doesn't make sense
across several installations on one computer.

> Right now when I attempt to mount it, I am asked for root password.
> Not acceptable.

What a user can mount is controlled by the option "user" in /etc/fstab.
Even if a user can mount a filesystem that doesn't mean she can read or
write any files in it after mounting. That is controlled by the
permissions in the filesystem.

> tomas' reply confused me ;/

I think that is because you have a misunderstanding that makes you want
to solve your problem the wrong way. Maybe it helps to restate what
exactly you want to do.

If all you want is to exchange a few files (office documents, music,
videos etc.) between separate OS installations the easiest way is to
format one partition as FAT filesystem. That way you won't have to worry
about permissions.

J.
-- 
When I am at nightclubs I enjoy looking at other people and assessing
their imagined problems.
[Agree]   [Disagree]
                 <http://archive.slowlydownward.com/NODATA/data_enter2.html>

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#173856

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On Tue, Oct 25, 2016 at 11:33:23AM -0500, Richard Owlett wrote:
> On 10/25/2016 10:40 AM, Greg Wooledge wrote:
> >On Tue, Oct 25, 2016 at 10:32:29AM -0500, Richard Owlett wrote:
> >>I'm in a multi-boot environment, multiple installs of Debian.
> >>I want all install to have read/write/execute permissions.
> >>The partition will effectively be serving as a common scratch pad
> >>in order to exchange information. There is organically a single
> >>user, [*ME*] and there is *NO* networking of any sort whatsoever.
> >
> >The simplest way would be to synchronize your UID across all your
> >installed operating systems.  If your UID is, let's say, 1000 on every
> >system, and the files on the partition are owned by user 1000, then
> >user 1000 (you) will have ownership of the files whenever you mount
> >the partition.
> 
> That sounds like what I want.
> I had previously created a ext2 partition on /dev/sda10 and a label
> of jessie-dvds .
> How do I inform the "WORLD" that it belongs to UID 1000?
> Right now when I attempt to mount it, I am asked for root password.
> Not acceptable.

I think Greg nailed it: there are two issues at work.

- - First, to be able to *mount* the thing, you gotta be root. Unless
  root (i.e. the admin) has set things up to allow (some, all) users
  to mount the thing. What thing and where is pretty tightly controlled
  (you set up a device and mount point in fstab and add the option
  "user", as Greg pointed out; you can even specify some users &
  groups if you want finer control -- e.g. a group "backup" should
  be able to mount backup media). See the man page for "mount" for
  the gory details.

- - Second, once mounted (and *if* the file system has provisions
  for that: all the DOS heirs like vfat &c don't), the files [1]
  "remember" whom (user and group) they belong to and what permissions
  they have (and perhaps a couple of other things, if you have
  extended attributes) If you are multi-booting, it's possible that
  you are a different user [2] on each operating system, and suddenly
  find out you home belongs to someone else.

> tomas' reply confused me ;/

Sorry to hear that. Seems I've been too terse (again :). My
reply concerned "Second" above: There are
file systems which are constantly coping with this user ID problem
(NFS, as a network file system comes to mind). Those have a facility
to "map" user IDs at boot time (i.e. stating that "user 1000 at
machine A is actually the same as user 1003 at machine B".

Most file systems intended to be mounted locally don't have that:
therefore synchronizing the user IDs on alternatively booted OSes
(or on OSes sharing a removable medium) makes sense.

Failing that, you can make "everything accessible by everyone"
(the DOS solution: by accident you get that when the file system
in question is vfat) or there is bindfs, which is... interesting
but may bring along some complexities of its own.

regards

[1] technically it's at the inode level where such things are stored.
[2] you may be called the same on those two OSes, but it's the user
   ID what matters, since that is what is stored on the file's inode.

- -- tomás
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#173858

[Multipart message — attachments visible in raw view] — view raw

On Wednesday, October 26, 2016 04:09:41 AM tomas@tuxteam.de wrote:
> On Tue, Oct 25, 2016 at 11:33:23AM -0500, Richard Owlett wrote:
> > On 10/25/2016 10:40 AM, Greg Wooledge wrote:
> > >On Tue, Oct 25, 2016 at 10:32:29AM -0500, Richard Owlett wrote:
> > >>I'm in a multi-boot environment, multiple installs of Debian.
> > >>I want all install to have read/write/execute permissions.
> > >>The partition will effectively be serving as a common scratch pad
> > >>in order to exchange information. There is organically a single
> > >>user, [*ME*] and there is *NO* networking of any sort whatsoever.

This could be another option:

The following description is not complete, but in general, after some of the 
installs (probably all but one), you could use the -u option of useradd to 
create a new userid with a specified UID.  

To that end, on installation of one (the first) system, specify your desired / 
preferred username, and after the install, check its UID. 

During the installation of future systems, specify a dummy username.  After 
the install, go back and create a new user with your preferred username and 
the same UID as used in the installation of the first system (using -u).  Then 
(for "completeness" / "cleanliness") delete the dummy username and associated 
files directories (e.g., /home/<dummy_username>).

A problem with this is that your configureation files (hidden in 
/home/<preferred_username> may be ideal for one system but not very 
appropriate for some of the other systems.

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#173862

Synchronizing your user account's UID across all of your own local
operating system installations is probably easier than most of the
workarounds that have been suggested.  There may not even be any
work required -- if you've always just followed the defaults, then
your primary user account is probably UID 1000 on every system, and
you're done.

If one of the systems has your UID as something else, you can logout,
login as root, change the UID in /etc/passwd, then chown every file
that you owned to the new UID.  For example, using find:

cd /each/file/system/one/at/a/time
find . -xdev -user 500 -exec chown 1000 {} +
cd /the/next/file/system
find . -xdev -user 500 -exec chown 1000 {} +
etc.

(I would not recommend trying it as one gigantic find from / because
of the file systems like /sys and /proc, which should probably be
skipped.  It's easier to do it the way I showed.)

(If the user had any long-running jobs, they should be killed and
restarted under the new UID.  Logging out *probably* gets most of them
under most circumstances, but you never know.  When in doubt, reboot.)

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#173863

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On Wed, Oct 26, 2016 at 08:28:34AM -0400, Greg Wooledge wrote:
> Synchronizing your user account's UID across all of your own local
> operating system installations is probably easier than most of the
> workarounds that have been suggested.

We are in violent agreement. I added bindfs as an additional
option which might come in handy when syncronizing the UID is
not what you want (getting a medium from elsewhere with an ext4
file system, and which you don't want to change significantly --
i.e. read & add some files but ot bulk-change all UIDS -- comes
to mind).

But it's definitely more work to do it right.

For Richard's use case, synchronizing (if even necessary, as you
point out) seems the way to go.

regards
- -- tomás
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#173895

On Wed, 2016-10-26 at 08:28 -0400, Greg Wooledge wrote:
> cd /each/file/system/one/at/a/time
> find . -xdev -user 500 -exec chown 1000 {} +
> cd /the/next/file/system
> find . -xdev -user 500 -exec chown 1000 {} +
> etc.
> 
> (I would not recommend trying it as one gigantic find from / because
> of the file systems like /sys and /proc, which should probably be
> skipped.

Which the -xdev option you specify will do anyway...

There's still the issue of using find on other filesystems that may be
mounted (e.g. if there's more than one partition or disk normally
mounted). And then there's group ownerships to consider.

Definitely a good thing to try and not get into the situation of wanting
to change user id in the first place. E.g. by creating all users in the
same order (assuming the systems are all the same distro) which is what
I do as a early step after installing a new system.

-- 
Tixy

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