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
Related
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!
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
Produces the following command on Ubuntu 64bit on VMWare:
mount /dev/sda1 /newroot
cd /newroot
mkdir old-root
pivot_root . old-root
I get an error that I do not understand
pivot_root: device or resource busy
Any ideas?
I saw the same error when the new root directory is a plain directory. When the new root is a mount, it will be ok. A bind mount of a directory is ok too. Also need to make sure the root directory permission is 0755, and owned by the root user.
The related answer states that you need to umount /proc first. I do not see the same.
The host ubnutu is 16.04 and it pivots into 18.04. Used unshare -m -p -f /bin/bash, followed by pivot_root . old_root. The -f is necessary to avoid a memory allocation error.
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
?
I'm trying to run a mumble server (umurmur) on my dd-wrt router (Buffalo WZR-HP-AG300H). I flashed one of the recent community versions of dd-wrt on the device (SVN Rev.: 23320), it has an Atheros CPU inside.
After that I mounted a USB pendrive into the filesystem using these guides (Guide 1, Guide 2) and created writable directories. Here is my startup-script saved to nvram (via web-gui)
EDIT: USB pendrive should be partioned before using it with DD-Wrt.
#!/bin/sh
sleep 5
insmod mbcache
insmod jbd
insmod ext3
mkdir '/mnt/part1'
mkdir '/mnt/part2'
mount -t ext3 -o noatime /dev/sda5 /mnt/part1 # /dev/sda5 -> partition on USB pendrive
mount -t ext3 -o noatime /dev/sda7 /mnt/part2 # /dev/sda7 -> partition on USB pendrive
swapon /dev/sda6 # /dev/sda6 -> partition on USB pendrive
sleep 2
if [ -f /mnt/part1/optware.enable ];then
#mount -o bind /mnt/part2 /mnt/part1/root
mount -o bind /mnt/part1 /jffs
mount -o bind /mnt/part1/etc /etc
mount -o bind /mnt/part1/opt /opt
mount -o bind /mnt/part1/root /tmp/root
else
exit
fi
if [ -d /opt/usr ]; then
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/lib:/usr/lib:/opt/lib:/opt/usr/lib:/jffs/usr/lib:/jffs/usr/local/lib
export PATH=$PATH:/bin:/sbin:/usr/bin:/usr/sbin:/jffs/bin:/opt/bin:/opt/sbin:/opt/usr/bin:/opt/usr/sbin
export IPKG_INSTROOT=/opt
else
exit
fi
The script works well and I can use opkg to install packages. I can also run umurmur manually but I'm struggling on making umurmur autostart. I recognized that the umurmur startup script placed in /opt/etc/init.d/ requires arguments like start and stop but it seems they are called without any arguments.
Another way described here did not work too.
Has anyone a working solution on problems like these? Please help!
Optware runs on Broadcom routers only. Your's has an Atheros chipset.
Taken from this page: Link
Its unclear i the page you referred to has changed - and indeed my setup is fairly different to yours, but to get scripts working on startup I did the following -
mkdir -p /jffs/etc/config
copy script into /jffs/etc/config directory, renaming it to end with .startup
chmod 755 /jffs/etc/config/scriptname.startup