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1. 先查看第一个空闲loop设备
- sudo losetup -f
- /dev/loop0
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2. 使用上一步得到的设备名,第一次创建loop设备
- sudo losetup /dev/loop0 archlinux-2008.06-core-i686.img
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3. 查看信息
- sudo fdisk -lu /dev/loop0
- Disk /dev/loop0: 322 MB, 322469376 bytes
- 53 heads, 12 sectors/track, 990 cylinders, total 629823 sectors
- Units = sectors of 1 * 512 = 512 bytes
- Disk identifier: 0x00000000
- Device Boot Start End Blocks Id System
- /dev/loop0p1 * 63 629822 314880 83 Linux
- Partition 1 has different physical/logical beginnings (non-Linux?):
- phys=(0, 1, 1) logical=(0, 5, 4)
- Partition 1 has different physical/logical endings:
- phys=(39, 52, 12) logical=(990, 15, 3)
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我们可以看到,该镜像只有一个分区(loop0p1),从第63扇区开始(Start列),每扇区512字节(Units = sectors of 1 * 512 = 512 bytes),我们算出offset,下面mout命令会用到:
4. mout
- sudo losetup -o 32256 /dev/loop1 archlinux-2008.06-core-i686.img
- sudo mount -o loop /dev/loop1 /mnt/
- ls /mnt/
- addons archlive.sqfs boot lost+found
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事实上,fdisk可以直接查看img文件(虽然功能不全,下面会说到),mount可以自动创建loop设备,所以上面步骤可以简化为:
I. 查看信息
- sudo fdisk -lu archlinux-2008.06-core-i686.img
- You must set cylinders.
- You can do this from the extra functions menu.
- Disk archlinux-2008.06-core-i686.img: 0 MB, 0 bytes
- 53 heads, 12 sectors/track, 0 cylinders, total 0 sectors
- Units = sectors of 1 * 512 = 512 bytes
- Disk identifier: 0x00000000
- Device Boot Start End Blocks Id System
- archlinux-2008.06-core-i686.img1 * 63 629822 314880 83 Linux
- Partition 1 has different physical/logical beginnings (non-Linux?):
- phys=(0, 1, 1) logical=(0, 5, 4)
- Partition 1 has different physical/logical endings:
- phys=(39, 52, 12) logical=(990, 15, 3)
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第一行抱怨不能得到cylinders,原因是普通文件上没有实现ioctl操作,我们可以看到0 cylinders,但这对我们不重要,关键是我们依然可以得到第一个分区(archlinux-2008.06-core-i686.img1)的偏移值
II. 直接mount
- sudo mount -o loop,offset=32256 archlinux-2008.06-core-i686.img /mnt/
- ls /mnt/
- addons archlive.sqfs boot lost+found
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参考Loop-mounting partitions from a disk image |
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