Permission denied - USB drive

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Anonymous user -  
mamiemando Posted messages 33228 Registration date   Status Moderator Last intervention   -
Hello,

I currently have a Raspberry Pi 3 B.

I have plugged in a USB stick, and I am unable to copy a file or folder onto it.
(It works in root, BUT):

I have an open proftpd server, and I want to put files on this USB stick, but I don't have the permissions.

-I would like to know how to grant all rights on this stick to all users of the machine.

Thank you in advance :)

1 answer

mamiemando Posted messages 33228 Registration date   Status Moderator Last intervention   7 940
 
Hello,

Generally speaking, it is not a good idea to grant access rights to everyone on a key. Typically, only the user who mounted the key has write permissions on it, and that is the correct approach. When access needs to be granted to multiple users, it is better to define a group that includes the people who have access to the key in question.

In any case, all of these questions are resolved at the time of mounting the key (see command
mount
), which allows you to specify the owner user of the key, the owner group, and the associated rights to the files on the key.

In your case, the key will be identified by a device (for example
/dev/sdb1
, assuming that
/dev/sda
corresponds to your hard drive). You can find this information using the command
sudo fdisk -l
.

Next, you need to create an empty directory (mount point) where the key will appear. Let's say
/media/usb
.

sudo mkdir -p /media/usb


Then you mount the key, with the right options (once again, I insist: this is NOT a command I recommend, but it does what you're asking):

sudo mount -o default,rw,user,dmask=000,fmask=111 /dev/sdb1 /media/usb


For more details, see
man mount
and this link to understand mask issues. Basically,
dmask
and
fmask
correspond to the rights associated with directories and regular files.

To understand what follows, read
man chmod
beforehand to understand how the octal syntax used by this command is defined.

The mask values correspond to the complement (in the mathematical sense) of the mask passed to the
chmod
command (so for example, applying
chmod 755
on directories means setting a
dmask
equal to
022
). To put it simply,
mask_chmod + dmask = 777
. The principle is the same for
fmask
.

Good luck!
0
Anonymous user
 
Well.. I'm going to spend another 5 hours learning new things. Thank you ❤️
0
Anonymous user
 
Thank you mamiemando, I managed to do it thanks to a Ubuntu forum. I just copied 2-3 lines into the /etc/fstab file.

For the command
sudo mount -o default,rw,user,dmask=000,fmask=111 /dev/sdb1 /media/usb
. I looked at (and tried to understand at the same time) the permissions, and I saw that default could be an issue, so I removed it, and it worked :D

I restarted the Raspberry, and :) it didn't work anymore :-| I went back to the /etc/fstab file to remove the default that I hadn't seen.

Now it's perfect.

Thank you <3
0
mamiemando Posted messages 33228 Registration date   Status Moderator Last intervention   7 940
 
Congratulations and best wishes for the future :-)
0