I am new in AWS. I have few questions about command line.
1. `mkfs -t ext4 /dev/xvdf`
This command is for make file system. What does -t means?
2. `umount -d /dev/xvdf`
This command is for umount file system. What does -d means?
Is there any source I can learn abut these commands like -t, -s, -d ....
When using the mkfs wrapper, include the -t fstype option to specify the type of file system to be built. If not specified, the default file system type, ext2, is created.
(https://linux.die.net/man/8/mkfs)
-d is used in case the unmounted device was a loop device, also free this loop device.
(https://linux.die.net/man/8/umount)
mkfs -t ext4 /dev/xvdf
Here -t denotes "File System".
and:
umount -d /dev/xvdf
Here "umount" use to unmounted and -d denotes the unmounted device was a loop device, also free this loop device.
Related
For which command can create a filesystem and append it into /etc/fstab automatically?
Just like the AIX command crfs -v jfs2 -d LV01 -m /backup -A yes . The option -A means it will mount on next boot automatically, and I even don't need to modify /etc/filesystems (as /etc/fstab on Linux).
There aren't such commands, but this can be easily scripted.
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
I am new to fuse. When I try to run a FUSE client program I get this error:
fuse: mountpoint is not empty
fuse: if you are sure this is safe, use the 'nonempty' mount option
I understand that a mountpoint is the directory where you will logically attach the FUSE filesystem. What will happen if I mount to this location? What are the dangers? Is it just that the directory will be overwritten? Basically: what will happen if you mount to a non empty directory?
You need to make sure that the files on the device mounted by fuse will not have the same paths and file names as files which already existing in the nonempty mountpoint. Otherwise this would lead to confusion. If you are sure, pass -o nonempty to the mount command.
You can try what is happening using the following commands.. (Linux rocks!) .. without destroying anything..
// create 10 MB file
dd if=/dev/zero of=partition bs=1024 count=10240
// create loopdevice from that file
sudo losetup /dev/loop0 ./partition
// create filesystem on it
sudo e2mkfs.ext3 /dev/loop0
// mount the partition to temporary folder and create a file
mkdir test
sudo mount -o loop /dev/loop0 test
echo "bar" | sudo tee test/foo
# unmount the device
sudo umount /dev/loop0
# create the file again
echo "bar2" > test/foo
# now mount the device (having file with same name on it)
# and see what happens
sudo mount -o loop /dev/loop0 test
Just add -o nonempty in command line, like this:
s3fs -o nonempty <bucket-name> </mount/point/>
Apparently nothing happens, it fails in a non-destructive way and gives you a warning.
I've had this happen as well very recently. One way you can solve this is by moving all the files in the non-empty mount point to somewhere else, e.g.:
mv /nonEmptyMountPoint/* ~/Desktop/mountPointDump/
This way your mount point is now empty, and your mount command will work.
For me the error message goes away if I unmount the old mount before mounting it again:
fusermount -u /mnt/point
If it's not already mounted you get a non-critical error:
$ fusermount -u /mnt/point
fusermount: entry for /mnt/point not found in /etc/mtab
So in my script I just put unmount it before mounting it.
Just set "nonempty" as an optional value in your /etc/fstab
For example:
## mount a bucket
/usr/local/bin/s3fs#{your_bucket_name} {local_mounted_dir} fuse _netdev,url={your_bucket_endpoint_url},allow_other,nonempty 0 0
## mount a sub-directory of bucket, Do like this:
/usr/local/bin/s3fs#{your_bucket_name}:{sub_dir} {local_mounted_dir} fuse _netdev,url={your_bucket_endpoint_url},allow_other,nonempty 0 0
force it with -l
sudo umount -l ${HOME}/mount_dir
I had a typo in my fstab and it boots to a commandline but is readonly, I know what the error is but i can't change it because it's mounted as readonly. I want to mount the filesystem and make the changes. I know I can boot a live distro and edit it that way, but i was wondering if there was an easier way to do it.
It's debian lenny by the way.
Yes, if you end up in single-user mode with a readonly root, try:
mount / -o remount,rw
Maybe a -n is necessary, maybe not. That should remount the root fs read/write (assuming there's nothing wrong with it).
I know that question is outdated, but saw it, because nowadays got in the same trouble.
I broke my fstab manually (make a typo in parameter).
That was very easy to correct fstab from readonly mode. We must mount / in read-write mode.
If /etc/fstab is correct, you can simply type:
mount -n -o remount /
But if /etc/fstab is wrong (as it was in my case), you must give the device name and possibly the type, too: e.g.
mount -n -o remount -t extX /dev/hdaX /
Where extX is your filesystem type and /dev/hdaX -- is partition you use for your root mount point.
To see all your available partitions just type ls /dev/[sh]d*.
#mount -n -o remount,rw /
if /dev/sda1 is the real device, then do:
#mount -n -o remount,rw /dev/sda1 /
#troyane saved my hassle by providing
mount -n -o remount -t extX /dev/hdaX /
I was on Orangepi3 EMMC when I had a typo in UUID of root having ext4 filesystem.
The command remounted in read-write mode and I fixed my fstab
mount -n -o remount -t ext4 /dev/mmcblk2p1 /
My kernel command line looks like this:
$ cat /proc/cmdline
root=/dev/sda4 ro
$
Tell grub that it should omit passing "ro" to the kernel when booting (pressing esc, e on the entry you want edit will allow you to edit the arguments given to the kernel), and it will mount your root file system not read only anymore. Then you can change your /etc/fstab and restart.
In my case, in grub2 after pressing "e" I have changed "ro" to "rw init=/bin/bash" then the root filesystem is mounted read and write so I could change the content of /etc/fstab file.
If you have something wrong with your /etc/fstab file. Please follow the following steps.
boot your ubuntu system or restart your computer
since you can not start your system, you will encounter some errors like
“a start job is running for dev-disk-by....
(you may need pressing F2 key to come the linux command terminal to see this)
use command vi /etc/fstab and edit your fstab file
use # to commend out some problems and add something you want put in the fstab file.
finish editing. hit shift+z and save the modification
use command reboot to restart your system
it works again
Please comment here, if you have questions
I have a CIFS share mounted on a Linux machine. The CIFS server is down, or the internet connection is down, and anything that touches the CIFS mount now takes several minutes to timeout, and is unkillable while you wait. I can't even run ls in my home directory because there is a symlink pointing inside the CIFS mount and ls tries to follow it to decide what color it should be. If I try to umount it (even with -fl), the umount process hangs just like ls does. Not even sudo kill -9 can kill it. How can I force the kernel to unmount?
I use lazy unmount: umount -l (that's a lowercase L)
Lazy unmount. Detach the filesystem
from the filesystem hierarchy now, and
cleanup all references to the
filesystem as soon as it is not busy
anymore. (Requires kernel 2.4.11 or
later.)
umount -a -t cifs -l
worked like a charm for me on CentOS 6.3. It saved me a server reboot.
On RHEL 6 this worked:
umount -f -a -t cifs -l
This works for me (Ubuntu 13.10 Desktop to an Ubuntu 14.04 Server) :-
sudo umount -f /mnt/my_share
Mounted with
sudo mount -t cifs -o username=me,password=mine //192.168.0.111/serv_share /mnt/my_share
where serv_share is that set up and pointed to in the smb.conf file.
I had this issue for a day until I found the real resolution. Instead of trying to force unmount an smb share that is hung, mount the share with the "soft" option. If a process attempts to connect to the share that is not available it will stop trying after a certain amount of time.
soft Make the mount soft. Fail file system calls after a number of seconds.
mount -t smbfs -o soft //username#server/share /users/username/smb/share
stat /users/username/smb/share/file
stat: /users/username/smb/share/file: stat: Operation timed out
May not be a real answer to your question but it is a solution to the problem
There's a -f option to umount that you can try:
umount -f /mnt/fileshare
Are you specifying the '-t cifs' option to mount? Also make sure you're not specifying the 'hard' option to mount.
You may also want to consider fusesmb, since the filesystem will be running in userspace you can kill it just like any other process.
Try umount -f /mnt/share. Works OK with NFS, never tried with cifs.
Also, take a look at autofs, it will mount the share only when accessed, and will unmount it afterworlds.
There is a good tutorial at www.howtoforge.net
I had a very similar problem with davfs. In the man page of umount.davfs, I found that the -f -l -n -r -v options are ignored by umount.davfs. To force-unmount my davfs mount, I had to use umount -i -f -l /media/davmount.
umount -f -t cifs -l /mnt &
Be careful of &, let umount run in background.
umount will detach filesystem first, so you will find nothing abount /mnt. If you run df command, then it will umount /mnt forcibly.
Approaching this problem sideways:
If you can't unmount because the filesystem is busy, is your ssh/terminal session cd'd into the mount directory, therefore making the filesystem busy?
For me, the solution was to cd into my home, then sudo umount worked flawlessly.
cd ~
umount /path/to/my/share
I would post this as a comment, but I have insufficient reputation. Hoping to spare someone else the forehead slap.
I experienced very different results regarding unmounting a dead cifs mount and found several tricks to bypass the problem temporarily.
Let's start with the mountpoint command. It can be useful to analyze the status of a mount:
mountpoint /mnt/smb_share
Usually it returns is a mountpoint or / is not a mountpoint.
But it can even return:
No such device
Transport endpoint is not connected
<nothing / stale>
For every result expect of is not a mountpoint there is a chance of unmounting.
You could try the usual way:
umount /mnt/smb_share
or force mode:
umount /mnt/smb_share -f
But often the force does not help. It simply returns the same nasty device is busy message.
Then the only option is to use the lazy mode:
umount /mnt/smb_share -l
BUT: This does not unmount anything. It only "moves" the mount to the root of the system, which can be seen as follows:
# lsof | grep mount | grep cwd
mount.cif 3125 root cwd unknown / (stat: No such device)
mount.cif 3150 root cwd unknown / (stat: No such device)
It is even noted in the documentation:
Lazy unmount. Detach the filesystem from the file hierarchy
now, and clean up all references to this filesystem as soon
as it is not busy anymore.
Now if you are unlucky, it will stay there forever. Even killing the process probably does not help:
kill -9 $pid
But why is this a problem? Because mount /mnt/smb_share does not work until the lazy unmounted path is really cleaned up by the Linux Kernel. And this is even mentioned in the documentation of umount. "lazy" should only be used to avoid a long shutdown / reboot times:
A system reboot would be expected in near future if you’re
going to use this option for network filesystem or local
filesystem with submounts. The recommended use-case for
umount -l is to prevent hangs on shutdown due to an
unreachable network share where a normal umount will hang due
to a downed server or a network partition. Remounts of the
share will not be possible.
Workarounds
Use a different SMB version
If you still have hopes that the lazy unmounted path will ever be not busy anymore and cleaned up by the Linux Kernel or you can't reboot at the moment, then you are maybe lucky and your SMB server supports different protocol versions. By that we can use the following trick:
Lets say you mounted your share as follows:
mount.cifs //smb.server/share /mnt/smb_share -o username=smb_user,password=smb_pw
By that Linux automatically tries the maximum support SMB protocol version. Maybe 3.1. Now, you can force this version and it won't mount as expected:
mount.cifs //smb.server/share /mnt/smb_share -o username=smb_user,password=smb_pw,vers=3.1
But then simply try a different version:
mount.cifs //smb.server/share /mnt/smb_share -o username=smb_user,password=smb_pw,vers=3.0
or maybe 2.1:
mount.cifs //smb.server/share /mnt/smb_share -o username=smb_user,password=smb_pw,vers=2.1
Change the IP of the SMB server
If you are able to change the IP address or add a second IP to your SMB server, you can use this to mount the same server.
Dirty: Forward the traffic
Lets say the SMB server has the IP address 10.0.0.1 and the mount is really dead. Then create this iptables rule:
iptables -t nat -A OUTPUT -d 10.0.0.250 -j DNAT --to-destination 10.0.0.1
Now change your mount rule accordingly, so it mounts the samba server through IP 10.0.0.250 instead of 10.0.0.1 and voila, its mounted without server reboot. Dirty, but it works. PS This rule does not survive a reboot, so you should mount the SMB server manually and leave the /etc/fstab as usual.
More debugging
If you want to check if samba connection itself is theoretically working, you could try to list all SMB shares of the server through SMB3 as follows:
smbclient //smb.server -U "smb_user" -m SMB3 -L
or to view the content of a share with SMB1:
smbclient //smb.server -U "smb_user" -m NT1 -c ls
On RHEL 6 this worked for me also:
umount -f -a -t cifs -l FOLDER_NAME
A lazy unmount will do the job for you.
umount -l <mount path>