I am trying to create a dm-zero device and mount it,but getting the following errors during mount.I have been stuck here for very long. Any help will be appreciated.
Error
mount: wrong fs type, bad option, bad superblock on /dev/mapper/zero_1,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
steps I followed are:
dmsetup create zero_1 --table '0 20000 zero'
mkfs -t ext2 /dev/mapper/zero_1
mount -t ext2 /dev/mapper/zero_1 /mnt
dmesg says:
[ 2547.110310] EXT2-fs (dm-0): error: can't find an ext2 filesystem on dev dm-0.
Really? dm-zero creates device that returns only 0s. So you will never see ext2 filesystem.
Related
I ran the following command to install Nix on my Mac:
sh <(curl -L https://nixos.org/nix/install) --daemon --darwin-use-unencrypted-nix-store-volume
And I got the following error:
error: refusing to create Nix store volume because the boot volume is
FileVault encrypted, but encryption-at-rest is not available.
Manually create a volume for the store and re-run this script.
See https://nixos.org/nix/manual/#sect-macos-installation
https://nixos.org/nix/manual/#sect-macos-installation says:
If you're using a recent Mac with a T2 chip, your drive will still be encrypted at rest (in which case "unencrypted" is a bit of a misnomer). To use this approach, just install Nix with:
sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume
If you don't like the sound of this, you'll want to weigh the other approaches and tradeoffs detailed in this section.
I don't have a mac with a T2 chip, so what do I do?
I found some related github issues, but no direct answer.
I chose to use the Use a separate encrypted volume suggestion as outlined in by Philipp Haussleiter:
This approach only works if you have a Disk that is formated with APFS (that should always be the case, if your OS is running of a SSD).
You can check this with:
% diskutil list | grep APFS
…
0: APFS Container Scheme - +250.8 GB disk1
…
Create another Volume on your Disk for NIX:
% sudo diskutil apfs addVolume disk1 'APFS' nix
Will export new APFS Volume "nix" from APFS Container Reference disk1
Started APFS operation on disk1
Preparing to add APFS Volume to APFS Container disk1
Creating APFS Volume
Created new APFS Volume disk1s6
Mounting APFS Volume
Setting volume permissions
Disk from APFS operation: disk1s6
Finished APFS operation on disk1
Your disk may not be named disk1s6. Find the name of your disk with:
% diskutil list | grep nix
4: APFS Volume nix 7.7 GB disk1s6
Again, your disk may not be named disk1s6.
Encrypt disk:
You need to enter a passphrase for the encryption. You have to
remember that passphrase once – you can add it to your key chain later
on. After that the disk encryption will start in the background.
% sudo diskutil apfs encryptvolume disk1s6 -user disk
Passphrase for the new "Disk" user (672C4CFF-34C6-4407-83ED-294C1C42E161):
Repeat passphrase:
Starting background encryption with the new "Disk" crypto user on disk1s6
The new "Disk" user will be the only one who has initial access to disk1s6
The new APFS crypto user UUID will be 672C4CFF-34C6-4407-83ED-294C1C42E161
Background encryption is ongoing; see "diskutil apfs list" to see progress
Setup Mount Point:
MacOS Catalina does not allow to create folders directly under your
Root Path /. But we can use another method to have MacOS create that
folder for us. To do this, we have to add an entry into the file
/etc/synthetic.conf:
% sudo bash -c 'echo nix >> /etc/synthetic.conf'
Now, the next time, the system starts, a mount point /nix will be
created. The next task is to have our Volume mounted at Boot.
Setup Mount:
For the Mount Configuration, we need to the UUID of the Volume. We can
find this via the diskutil tool (again, your disk may not be named
disk1s6):
% diskutil info /dev/disk1s6 | grep UUID
We must edit /etc/fstab with vifs:
% sudo vifs
(vifs behaves just like vi, so use vi commands to edit the file):
UUID=1D9389C1-5676-4077-88F5-8D5304A0B1A6 /nix apfs rw
(Your UUID will be different!)
Reboot. You will get a GUI prompt to enter your encryption passphrase,
and save it to the keychain.
I then ran:
sh <(curl -L https://nixos.org/nix/install) --daemon
The --darwin-use-unencrypted-nix-store-volume option isn't necessary because we have an encrypted volume now.
I've been experimenting with running apps within a chroot-ed directory.
Many apps and binaries require access to items within /dev, such as /dev/null and /dev/random to work.
Is there a way to recreate or bind mount the /dev filesystem within a directory to this end?
I have tried the following without success:
(Where root is the directory I want to chroot into)
$ sudo bindfs -o dev -o allow_other /dev ./root/dev/
Leading to:
$ cat ./root/dev/urandom
cat: ./root/dev/urandom: Operation not permitted
$ mount -t devfs devfs ./root/dev
Leading to:
$ cat ./root/dev/urandom
cat: ./root/dev/urandom: Device not configured
Attempting to manually make the devices with mknod doesn't work either.
$ sudo mknod null c 1 3
$ sudo chmod 666 ./null
$ cat ./null
cat: ./null: Operation not permitted
Is there a way to either use the existing /dev items within a chroot or to recreate them?
Unfortunately, there doesn't appear to be much documentation of using chroot with OSX/macOS on the internet.
Operating System Details: macOS Mojave, 10.14.6. SIP enabled.
Well, this one is mainly on me being dumb.
sudo mount -t devfs devfs ./dev
Works just fine.
If the above command is ran without root, it will bind the devfs devices within ./dev, but all devices will respond with a "Device not configured" error. If it is ran as root, all ./dev devices will work as expected.
When booting a virtual server with Ubuntu 14.04/16.04 (I had the issues with both), it cant find the boot partition for root and the system falls to the initramfs shell with the following error:
(initframs) exit
Gave up waiting for root device. Common problems:
- Boot args (cat proc/cmdline)
- Check rootdelay= (did the system wait long enough?)
- Check root= (did the system wait for the right device?)
- Missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/mapper/CAC_VG-CAC_LV does not exist. Dropping to a shell!
if I type
ls /dev/mapper/
I still can see the partition mentioned in the error (and in the GRUB)
root=/dev/mapper/CAC_VG-CAC_LV
cat output as suggested in the error message
(initframs) cat /proc/cmdline
BOOT_IMAGE=/vmlinuz-4.4.0-66-generic root=/dev/mapper/CAC_VG-CAC_LV ro
Notice: it seems to mount the device in Read-Only (ro). Maybe I should change this after I manage to start the system...
If I type exit I get the same error as above.
Then I try to mount:
mount -t ext4 /dev/mapper/CAC_VG-CAC_LV
mount: can't find /dev/mapper/CAC_VG-CAC_LV in /etc/fstab`
I had the same problem after a fresh install of Ubuntu 14.04
And this actually worked!!
mount -o remount, rw /
lvm vgscan
lvm vgchange -a y
mount -t ext4 /dev/mapper/CAC_VG-CAC_LV /root
exit
To mount CIFS presently I use system() call in source, this works. If I try to run command manually on shell it works too.
$ mount -t cifs //IP/dir /mnt -o user=name,pass=PASS,domain=mydomain,nounix
$ mount.cifs //IP/dir /mnt -o user=name,pass=PASS,domain=mydomain,nounix
But if i replace the same command with exec() family i see errors.
if(fork() == 0)
{
if (execl("/bin/mount", "/bin/mount", "-t", "cifs", "//IP/dir", "/mnt",
"-o user=name,pass=PASS,domain=mydomain,nounix", (char*) NULL) < 0)
...
}
else
...
Error: mount: mounting cifs on //IP/dir /mnt failed: No such file or directory. It looks like mount directory "/mnt" is not recognized or not seen by mount process.
Tried below things but no luck:
as suggested in forums tried using sec=ntlmv2 and other options
with mount.cifs
combined arguments "//IP/dir" and "/mnt" as "//ipaddr/dir /mnt"
What would be the cause here? How to see the command line parameters of the exec()'ed program ?
Version of mount:
mount.cifs version: 1.14-x
Regards, - AK
Used strace() to find the arguments passed to execl(). Solved my issue by using system calls mount() and umount().
Presuming you have installed samba
sudo apt-get install samba
In the Global section of the file /etc/samba/smb.conf you should have this :-
workgroup = WORKGROUP
netbios name = PCNAME
name resolve order = bcast host
Change WORKGROUP and PCNAME accordingly. Set the name resolve order as shown in order to browse windows shares using Nautilus.
I created an EC2 instance (Ubuntu 64 bit) and attached a volume from a publicly available snapshot to the instance. I successfully mounted the volume. I am supposed to be able to run a script from this attached volume using the following steps as explained in the tutorial:
Log in to your virtual machine.
mkdir /space
mount /dev/sdf1 /space
cd /space
./setup-script
The problem is that, when I try: ./setup-script I got the following message:
-bash: ./setup-script: No such file or directory
What is the problem ? How can I search for the ./setup-script in the whole machine ? I'm not very familiar with linux system. Please, help.
For more details about the issue: Look at my previous post:
Error when mounting drive
# Is it a script or an executable ?
file /space/setup-script
# Show us it is readable and marked executable
ls -l /space/setup-script
# Mark it executable
chmod a+x /space/setup-script
# Then try running it again? If you know it is shell script you can:
bash /space/setup-script
If still not working, then we get into why it wont execute.
grep space /proc/mounts
Does the options it have noexec ?
Try mount -o remount,exec /space now try your instructions again.
NOTE: All commands presume you are 'root' user or you can 'sudo' each command.
It is possible that you have mounted the wrong device. I've just recalled a trick you can use to find the device name of an EBS volume in Linux, since it is often different from the device name reported in the AWS console. First unmount the device in Linux, then detach it from the instance using the AWS console, so we go back to the original state. Now run this command in Linux:
cat /proc/partitions
The command will show the volumes currently attached. The next step is to attach the volume to the instance using the AWS console, and then to run that same command again in Linux. You should see an additional line appear. This line will tell you the name of the device to mount. For example, I get this output in my Ubuntu instance:
major minor #blocks name
202 1 8388608 xvda1
202 80 8388608 xvdf
The first line was already there before I attached the volume, so I know this is my root volume. The second line is the one that appeared, so in this case, the device to mount would be /dev/xvdf.