![]() If you have any questions, comments, or suggestions for future tips, please contact us. We hope that you've found this tip useful. rw-r-r- 1 root root 0 Dec 24 02:01 myNewFile Maybe this serves as an explanation: The kernel implements several layers of abstraction so that it can treat different hardware the same way. So you always use/need to use the loop back device when mounting a file. ĭrwxr-xr-x 5 root root 4096 Dec 24 01:41. Technically a loop device is a block device that writes to a file, rather than a piece of hardware. # cd /mnt/image # touch myNewFile # ls -lĭrwxr-xr-x 3 root root 1024 Dec 24 02:01. tmp/loopfs.img on /mnt/image type ext3 (rw,loop=/dev/loop0) # umount /mnt/image & losetup -d /dev/loop0 # mount -o loop /tmp/loopfs.img /mnt/image # mount | grep loopfs Unmount the file system and detach the loop device, then mount the file system with the ? loop? mount option. # mkdir /mnt/image & mount /dev/loop0 /mnt/image # mount | grep loop0 Use tune2fs -c or -i to override.Ĭreate a mount point, and mount the new file system. This filesystem will be automatically checked every 29 mounts orġ80 days, whichever comes first. Writing superblocks and filesystem accounting information: done # losetup /dev/loop0 /tmp/loopfs.img # file -s /dev/loop0Ĭreate an Ext3 file system on the device.ĥ00 blocks (5.00%) reserved for the super userĨ192 blocks per group, 8192 fragments per group Using the losetup(8) command, associate our new file with a loop device. # dd if=/dev/zero of=/tmp/loopfs.img bs=1024 count=10000ġ0000+0 records out # file /tmp/loopfs.img In addition, you can create file systems within a file!Ĭreate a zero-filled file for use in this example. # mount -o loop -t iso9660 FILENAME.iso /mnt/isoimage This will give you access to the files in the ISO without you first having to burn it to a CD or DVD.įor example if you would like to mount FILENAME.iso on /mnt/isoimage you would run the following commands:Ĭreate the mount point (if it does not already exist). Once you have downloaded an ISO image to your Linux machine, you can mount it as a loop device. dev/loop1 /dev/loop3 /dev/loop5 /dev/loop7 dev/loop0 /dev/loop2 /dev/loop4 /dev/loop6 Well, in order to continue this tip we need to load the loop device.Īre the /dev/loop* devices created? # ls /dev/loop* In the previous example we illustrated what would occur if the loop device was not mounted. There is no loop device kernel module loaded. # ls /dev/loop* ls: /dev/loop*: No such file or directory There are no /dev/loop* device special files. Hi all I have setup a chroot jail with all the required utilities and want the user to be able to create and mount a loopback device. # mount -o loop RHEL52-DVD.iso /mnt/image mount: could not find any device /dev/loop# One obvious indicator that the module is not loaded is the lack of any loop device special files in /dev, which would become evident if you tried to mount an ISO file to a mount point. Since the later tips rely on the fact that the loop device is actually loaded into the kernel, let's explore how we can determine whether or not it is actually loaded. Is the Loop Device Loaded into the Kernel? Is the Loop Device Loaded into the Kernel?.This is most commonly used to mount ISO image files, but it can be used for other files as you will soon see. The loop device is a kernel module that can be used to mount a file as a file system. This tip (or more appropriately tips) cover the Linux loop device.
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