[gentoo-user] pmount question

[gentoo-user] pmount question

[David Relson]

G'day,

My USB subsystem is working much better now (than it was this
weekend).  /etc/fstab had a reference to "/dev/hdb" which no my current
kernel no longer supports.  Removing this has improved flash drive
mounting a whole lot!

I've also modified /etc/udev/rules.d/10-local.rules to use "pmount
device label" rather than "mount -a".  This is mounting flash drives
in /media as desired:

root@osage media # ls -l
total 32
drwx------ 19 root plugdev 16384 Dec 31  1969 PNY
drwx------  3 root plugdev 16384 Dec 31  1969 SD_2G

However (as can be seen above) the permissions are 700, which
makes the drives unusable by members of the plugdev group.

Alternatively, I can use "pmount -u 007 device label" to provide full
access to the plugdev group.  This seems awkward and inelegant.

What's the right way to use pmount and set permissions?

Regards,

David

Re: [gentoo-user] pmount question

[Neil Bothwick]

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On Mon, 21 Feb 2011 18:58:38 -0500, David Relson wrote:

> I've also modified /etc/udev/rules.d/10-local.rules to use "pmount
> device label" rather than "mount -a".  This is mounting flash drives
> in /media as desired:

mount -a was always a bad idea, because it could potentially affect
drives other than the one the rule was intended for. What would happen if
you had unmounted a filesystem to run fsck on it and you plugged in your
USB drive?
> 
> root@osage media # ls -l
> total 32
> drwx------ 19 root plugdev 16384 Dec 31  1969 PNY
> drwx------  3 root plugdev 16384 Dec 31  1969 SD_2G
> 
> However (as can be seen above) the permissions are 700, which
> makes the drives unusable by members of the plugdev group.
> 
> Alternatively, I can use "pmount -u 007 device label" to provide full
> access to the plugdev group.  This seems awkward and inelegant.
> 
> What's the right way to use pmount and set permissions?

pmount is supposed to be run as a user and it mounts the filesystem owned
by the user running it. If you only have a single user, you could call
pmount with su. If you have multiple users, you should be letting a
desktop tool handle the mounting anyway.


-- 
Neil Bothwick

We all know what comes after 'X', said Tom, wisely.

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Re: [gentoo-user] pmount question

[Neil Bothwick]

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On Mon, 21 Feb 2011 21:01:25 -0500, David Relson wrote:

> > pmount is supposed to be run as a user and it mounts the filesystem
> > owned by the user running it. If you only have a single user, you
> > could call pmount with su. If you have multiple users, you should be
> > letting a desktop tool handle the mounting anyway.  

> I've heard "pmount ... as a user" before, but never understood what it
> meant.  If "pmount ..." is run by a rule
> in /etc/udev/rules.d/10-local.rules, how is it known what userid to
> use?  Does "pmount ... as a user" assume particular settings in gnome,
> the kernel, or ???

pmount is meant to be run by a normal user, usually from an automounter,
as its main objective is to allow normal users to mount removable devices
without fstab rules, while udev rules are run as root. So if you want it
to run as a user from a udev rule you'll have to use su, as in

su youruser -c 'pmount /dev/PTY'


-- 
Neil Bothwick

A consultant is a person who borrows your watch, tells you what time it
is, pockets the watch, and sends you a bill for it.

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Re: [gentoo-user] pmount question

[David Relson]

On Tue, 22 Feb 2011 08:37:06 +0000
Neil Bothwick wrote:

> On Mon, 21 Feb 2011 21:01:25 -0500, David Relson wrote:
> 
> > > pmount is supposed to be run as a user and it mounts the
> > > filesystem owned by the user running it. If you only have a
> > > single user, you could call pmount with su. If you have multiple
> > > users, you should be letting a desktop tool handle the mounting
> > > anyway.  
> 
> > I've heard "pmount ... as a user" before, but never understood what
> > it meant.  If "pmount ..." is run by a rule
> > in /etc/udev/rules.d/10-local.rules, how is it known what userid to
> > use?  Does "pmount ... as a user" assume particular settings in
> > gnome, the kernel, or ???
> 
> pmount is meant to be run by a normal user, usually from an
> automounter, as its main objective is to allow normal users to mount
> removable devices without fstab rules, while udev rules are run as
> root. So if you want it to run as a user from a udev rule you'll have
> to use su, as in
> 
> su youruser -c 'pmount /dev/PTY'

Neil:

I'm currently using "pmount -u 007 /dev/PTY" as this gives rwx
permissions for root and group plugdev, which is adequate for my
workstation (which only ever has me using it).

I've seen that Ubuntu with Gnome automounts USB sticks.  That seems
pleasantly convenient and is done without any rules (such as I
presently have) in /etc/udev/rules.d. Do you know what they're doing?

Regards,

David

Re: [gentoo-user] pmount question

[Neil Bothwick]

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On Tue, 22 Feb 2011 07:33:45 -0500, David Relson wrote:

> I've seen that Ubuntu with Gnome automounts USB sticks.  That seems
> pleasantly convenient and is done without any rules (such as I
> presently have) in /etc/udev/rules.d. Do you know what they're doing?

It's using the GNOME automounter, other desktops also do this and it is
more friendly than udev rules. I don't know the details because I have
never been able to stand GNOME for long enough to find out.


-- 
Neil Bothwick

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Re: [gentoo-user] pmount question

[Joost Roeleveld]

On Tuesday 22 February 2011 07:33:45 David Relson wrote:
> On Tue, 22 Feb 2011 08:37:06 +0000
> 
> Neil Bothwick wrote:
> > On Mon, 21 Feb 2011 21:01:25 -0500, David Relson wrote:
> > > > pmount is supposed to be run as a user and it mounts the
> > > > filesystem owned by the user running it. If you only have a
> > > > single user, you could call pmount with su. If you have multiple
> > > > users, you should be letting a desktop tool handle the mounting
> > > > anyway.
> > > 
> > > I've heard "pmount ... as a user" before, but never understood what
> > > it meant.  If "pmount ..." is run by a rule
> > > in /etc/udev/rules.d/10-local.rules, how is it known what userid to
> > > use?  Does "pmount ... as a user" assume particular settings in
> > > gnome, the kernel, or ???
> > 
> > pmount is meant to be run by a normal user, usually from an
> > automounter, as its main objective is to allow normal users to mount
> > removable devices without fstab rules, while udev rules are run as
> > root. So if you want it to run as a user from a udev rule you'll have
> > to use su, as in
> > 
> > su youruser -c 'pmount /dev/PTY'
> 
> Neil:
> 
> I'm currently using "pmount -u 007 /dev/PTY" as this gives rwx
> permissions for root and group plugdev, which is adequate for my
> workstation (which only ever has me using it).
> 
> I've seen that Ubuntu with Gnome automounts USB sticks.  That seems
> pleasantly convenient and is done without any rules (such as I
> presently have) in /etc/udev/rules.d. Do you know what they're doing?

Gnome (and most other desktop environments) can be configured to auto-mount a 
USB-drive, CDs,...

Gnome will, as is mentioned previously, probably use "pmount" started as the 
current user which will then mount the drive with the user as the owner.

udev-rules are only really needed when you don't (want to) use an automounter 
with your X-desktop.

I myself use KDE and there I can specify if I want a USB-drive mounted or not.
I believe I can also specify some USB-drives to auto-mount when I plug them 
in. But I do prefer to be able to decide each time as sometimes I just plug in 
my phone or camera to charge it. (My phone also acts like a usb-drive when so 
configured)

--
Joost

Re: [gentoo-user] pmount question

[Neil Bothwick]

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On Tue, 22 Feb 2011 14:32:23 +0100, Joost Roeleveld wrote:

> I myself use KDE and there I can specify if I want a USB-drive mounted
> or not. I believe I can also specify some USB-drives to auto-mount when
> I plug them in. But I do prefer to be able to decide each time as
> sometimes I just plug in my phone or camera to charge it. (My phone
> also acts like a usb-drive when so configured)

Yes, you can specify which devices are automounted. I have KDE mount USB
sticks, but not my phone - for the same reasons as you.


-- 
Neil Bothwick

Friends may come and go, but enemies accumulate.

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