Linux Command Learning Note--losetup command: Set up a looping device

Losetup command: Set up a loop device loop device can virtual a file into a block device, in order to simulate the entire file system, so that users can think of it as a hard disk drive, optical drive or floppy drives and other devices, and hang in as a directory to use.   is commonly used to load and access an. iso file as a looping device.   1, command parameter losetup: Set and Control loop (loop) device.   Syntax: Losetup loop device   parameters: Loop device can be/dev/loop0,/dev/loop1 .../dev/loop7-a shows the status of all loop devices. -D Dismount Device-e < encryption options > Start encryption encoding  -f look for the first unused loop device-O < offset > Set the data offset in bytes.   Example: (a) The 1.iso file virtual into a loop device under the shell input: losetup/dev/loop0  1.iso and then under the shell losetup/dev/loop0 will get some relevant information.   (ii) unloading as circulating equipment/dev/loop0losetup-d/dev/loop0 in operation Losetup/dev/loop0 It can be seen that the equipment has been removed.   (iii) find the first unused loop device losetup-f  (iv) displays all circulating device states that have been used losetup-a  combat: Create a 5M file and operate the virtual loop device. 1, create a file 5M files, 5,120 sectors, each sector size 1KDD If=/dev/zero  of=abc  bs=1k  count=51202, virtual cycle equipment losetup-f ABC   The ABC virtual into a loop device, specifically on which loop device with the-F automatic search. 3, format the virtual disk file mkfs.ext4/dev/loop04, mount the virtual disk file Mount/dev/loop0  /mnt/iso 5, you can copy the file to the inside or delete (test successful)  6, Unmount the file system Umount/mnt/iso7 and dismount the loop device. Losetup-d/dev/loop0  gave me the feeling that the loop is like a CD-ROM, and the file as a disc, put in the loop, and then mount it can be accessed, do not know how to understand it.

Linux Command Learning Note--losetup command: Setting up a looping device