Mount another virtual hard disk always belongs root owner, why? - linux

Environment is in virtual box,ubuntu 12.04. It has 2 disks, /dev/sda1 and /dev/sdb1 are both ext4 type filesystem.
Since /dev/sdb1 is add after system installed, so I want to mount it manually. I'd try this command:
sudo mount -o user,defaults /dev/sdb1 ~/project
No errors report. Then I get mount info by mount:
/dev/sdb1 on /home/igsrd/project rw,noexec,nosuid,nodev
But when I ls -l to see /home/igsrd I found its permission is still belongs root, so I can't touch anything in it. Why it still belongs root?
I have another machine running ubuntu 12.04,too. I mount another partition with same option will be fine, correct permission(ownership). Are any differences between them?

*nix permissions on a filesystem that supports them natively, e.g. ext4, will be maintained regardless of how it is mounted when using a proper filesystem driver, e.g. the native ext4 driver built into Linux.

Why don't you just (while still root) do this:
chown -R <your-user-name> ~<your-user-name>/project
?

Related

Load root filesystem from USB device

I'm trying to make a fast reboot to the other Linux system. First step is kernel loading, I make it with
sudo kexec --append='$(cat /proc/cmdline)' -l new_kernel.img --reuse-cmdline
sudo kexec -e
It works fine, but loads only kernel, not entire system.
How can I mount an *.img file with OS resources, located at USB as /? Preferable during kernel loading, but afterwards mount is still suitable. *.img format is not necessary, it can be unpacked before
As stark said, pivot root() was the call I was searching for. Commands to make a USB located at /dev/sdb1 a root directory:
sudo -s
mkdir /newroot
mount /dev/sdb1 /newroot
cd /newroot
mkdir oldroot
pivot_root . oldroot/
switch_root() deletes all files at the previous root dir, also there are few other differences, this answer might be useful

Cannot create a file because of permissions

I want to create a file in sys/kernel/security folder in Linux.
But sudo touch test returns permission error.
After sudo chmod 777 /sys/kernel/security it fails, so I tried to change permissions for /sys folder (yes, I know this is a bad way) and sudo -i. Files does not creates, but in all cases it sets correctly - drwxrwxrwx.
And now I actually have no ideas, so I hope to your tips.
Thanks.
/sys/kernel/security is Linux Kernel Security Module (LSM) space where kernel security module can show their data both r/w.
mount | grep security
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
This is another virtual file system mounted of /sys. You can't create files here and there is no meaning at all to create files here.
See, securityfs details here!

Ubuntu: create a new partition on /dev/sdb1 (which still has 1.5tb of free space) and mount it on /tmp/

As you can see /dev/sda is mounted to /. Thats where /tmp/ is located as shown image. Since It is running out of space on my / partition,I can't install caffe, and there is error: No space left on device.
Now I want to create a new partition on /dev/sdb1 (which still has 1.5tb of free space) and mount it on /tmp/.
Could you guys tell me how to create a new partition for solving this issue by linux command.
thanks
Just give the following command
To unmont the existing volume give the following
sudo umount /dev/sdb1
Note:- Make sure no process is using the particular directory
Then again mount it to /tmp
sudo mount /dev/sdb1 /tmp
or
cd /dev/ && sudo mount sdb1 /tmp

what causes permission of auto-mount in linaro linux

Sdcard is mounted automatically as root permission.
like this.
/dev/mmcblk1p1 on /media/linaro/11bf7464-471c-42ca-bbc8-d229a43e8fe51 type ext4 (rw,nosuid,nodev,relatime,data=ordered,uhelper=udisks2)
/etc/fstab is emtpy like below.
linaro#linaro-alip:/lib/udev$ cat /etc/fstab
# UNCONFIGURED FSTAB FOR BASE SYSTEM
did udisks mount the device? If so, where can I change mount permission option?
Sometimes, it is mounted as a linaro user.
What causes this difference? any idea?
For Gnone to disable Nautilus automount use this command:
gsettings set org.gnome.desktop.media-handling automount false

How to mount a qnx partition as read -write enabled only for executing particular lines of code?

ie the partition of interest is already mounted as read-only.the partition need to be mounted as a rw enabled partition for executing particular lines of script alone.After that the partition should go to it's previous state of read only.
Question is for QNX operating system. And correct way to remount partition as read/write can be done using below command.
mount -uw /
To remout a partition read-write:
mount /mnt/mountpoint -oremount,rw
and to remout read-only
mount /mnt/mountpoint -oremount,ro
you may be interested in remount option.
for example, this command is widely used in rooted androids.
mount -o remount,rw /system
mount -o remount,ro /system
mount(8) - Linux man page
Filesystem Independent Mount Options
remount
Attempt to remount an already-mounted filesystem. This is commonly used to change the mount flags for a filesystem, especially to make a readonly filesystem writeable. It does not change device or mount point.
The remount functionality follows the standard way how the mount command works with options from fstab. It means the mount command doesn't read fstab (or mtab) only when a device and dir are fully specified.
mount -o remount,rw /dev/foo /dir
After this call all old mount options are replaced and arbitrary stuff from fstab is ignored, except the loop= option which is internally generated and maintained by the mount command.
mount -o remount,rw /dir
After this call mount reads fstab (or mtab) and merges these options with options from command line ( -o ).

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