我的外部硬盘上有磁盘映像文件。我尝试使用 mac.dmg 文件提取文件，7z x mac.dmg结果如下：
Processing archive: mac.dmg
Extracting 0.MBR
Extracting 1.Type EE
Everything is Ok
Files: 2
Size: 250059350016
Compressed: 201276607141
我照做了file 1.Type EE，得到了：
1.Type EE: GPT data structure (nonstandard: at LBA 0), version 1.0, GUID: 66741e19-807b-4f4f-a1e4-652d7892adf3, disk size: 488397168 sectors (sector size unknown)
我不知道现在该怎么办。
附录：
与@the_Seppi 讨论了这个问题之后，我的情况如下：
使用：gdisk -l ubun.img我得到：
Caution: invalid main GPT header, but valid backup; regenerating main header
from backup!
Caution! After loading partitions, the CRC doesn't check out!
Warning! Main partition table CRC mismatch! Loaded backup partition table
instead of main partition table!
Warning! One or more CRCs don't match. You should repair the disk!
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: damaged
****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************
Disk ubun.img: 488397168 sectors, 232.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 66741E19-807B-4F4F-A1E4-652D7892ADF3
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 488397134
Partitions will be aligned on 8-sector boundaries
Total free space is 13 sectors (6.5 KiB)
Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI System Partition
2 409640 487127591 232.1 GiB AF00 Untitled 1
3 487127592 488397127 619.9 MiB AB00 Recovery HD
这样做：
sudo apt-get install hfsprogs
mkdir \mnt\backup
sudo mount -o force,loop,offset=$((409640*512)) -t hfsplus ubun.img /mnt/backup/
我明白了：
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
然后尝试dmesg | tail，我得到了这个：
[529744.283668] FAT-fs (loop0): Can't find a valid FAT filesystem
[529744.283832] hfsplus: unable to find HFS+ superblock
[530011.118941] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[530011.119017] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[530011.119052] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[530011.119127] FAT-fs (loop0): bogus number of reserved sectors
[530011.119130] FAT-fs (loop0): Can't find a valid FAT filesystem
[530011.119274] hfsplus: unable to find HFS+ superblock
[530073.047405] hfsplus: unable to find HFS+ superblock
[530292.332266] hfsplus: unable to find HFS+ superblock
答案1
从你所看到的，该文件实际上是一个磁盘映像。你需要使用 dmg2img ( sudo apt-get install dmg2img) 将其转换为 img 文件，然后你可以将生成的 img 文件挂载到循环设备中来浏览其内容：
mount -o loop example.img /home/you/dir