I have an .iso file which I would like to mount. I have made a folder in /mnt/iso as a mount point. Now I try:

sudo mount -o loop filename.iso /mnt/iso

and the reply is:

mount: you must specify the filesystem type

and the folder of /mnt/iso is empty. I have tried using

sudo mount -o loop -t ext4 filename.iso /mnt/iso

it says that mount: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error (and more text)...

I found the filesystem type from using df -T and mount at the command line.

What could be missing or wrong?

  • 1
    have you done an md5sum of the ISO to check that it is a valid ISO?
    – fossfreedom
    Jan 1, 2012 at 18:28
  • @fossfreedom, no I haven't, good idea, but I have no idea how, can you give me a hint? (is it possible that the .iso is faulty?)
    – Vass
    Jan 1, 2012 at 18:30
  • 1
    good Q&A here that should help... askubuntu.com/questions/31888/…
    – fossfreedom
    Jan 1, 2012 at 18:33
  • Did you read man mount? df -T and mount describe the current state of the system. If you ran the commands before you mounted a .iso, ...
    – waltinator
    Jan 1, 2012 at 19:32

1 Answer 1


The filetype you need for mounting a .iso formatted file is iso9660. Here's an example:

A good .iso:

walt@wombat:~(0)$ file  /usr/lib/memtest86+/memtest86+.iso  
/usr/lib/memtest86+/memtest86+.iso: # ISO 9660 CD-ROM filesystem data  MT410 ' (bootable)  `

A directory to mount it on:`

walt@wombat:~(0)$ ls -ld ~/tmp/mp  
drwxrwxr-x 2 walt walt 4096 2012-01-01 13:55 /home/walt/tmp/mp`  

The actual mount:

walt@wombat:~(1)$ sudo mount -t iso9660 /usr/lib/memtest86+/memtest86+.iso /home/walt/tmp/mp    
mount: warning: /home/walt/tmp/mp seems to be mounted read-only.`  

And here it is!

walt@wombat:~(0)$ ls !$  
ls /home/walt/tmp/mp  
boot  readme.txt  
walt@wombat:~(0)$  df -H /home/walt/tmp/mp  
Filesystem             Size   Used  Avail Use% Mounted on  
/dev/loop0             1.9M   1.9M      0 100% /home/walt/tmp/mp  
  • It may also be udf instead of iso9660. Likely if the image is meant for a DVD.
    – psusi
    Jan 1, 2012 at 19:25
  • 1
    That's why I used the file command, to be sure what the image was.
    – waltinator
    Jan 1, 2012 at 20:11

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