Mount *.img file

tobiasw · 10-17-2006, 05:42 AM

Hello,
Im trying to mount a img file on my Fedora linux distribution. Is there a command to find out what fs the img file is. Because im trying to mount the img file and the only fs what works is tmpfs, debugfs and proc. But the files in the mount directory are useless.

Here is what I tried:

#mount -o loop r2.img testdir
#mount -o loop -t debugfs r2.img testdir
#mount -o loop -t ext2,...

Thanks and regards
Tobias

druuna · 10-17-2006, 06:02 AM

Hi,

Most of the time *img's are iso's, try using -t iso9660

Hope this helps.

tobiasw · 10-17-2006, 06:19 AM

No luck.. its not mounting with iso9660,
i tried also with CD-Burner tools.. What possibilities exist to create a img File? My "pc" what i am working with have two img files , the first one (r1.img) i can mount with ext3, in this image i find startup files like grub, bzImage. The other image file r2.img I cannot mount. I tried to unzip the file too, but I get the message: r2.img not in gzip format.
Any Suggestions?

Thanks and regards
Tobias

pwc101 · 10-17-2006, 06:58 AM

try

Code:

file r2.img

to see what kind of file it is.

tobiasw · 10-17-2006, 07:26 AM

Thank you very much!

By typing "file r2.img"

I get:
r2.img: Squashfs filesystem, little endian, version 2.0 ...

I also can mount it then with squashfs:
mount -o loop -t squashfs r2.img testdir

But when I change, or try to create a file in this image, it gives me the Error message: (i did cp xxx.sh test.sh)

cp: cannot create regular fiel 'test.sh': Read-only file system.

Does anybody know how to change a file in this image?

Thanks and regards
Tobias

pwc101 · 10-17-2006, 07:31 AM

I don't know if this'll work, but when you mount it, if you do so with read-write permissions, perhaps you'll be able to modify it:

Code:

mount -o loop,rw -t squashfs r2.img testdir

I'm not at a linux machine, so I can't test that to see if it's right, but I think it is...

edit: your cp command is trying to copy xxx.sh to the current directory, which is presumably in the mounted image, in which case cp xxx.sh ~/test.sh will copy (and rename it to test.sh) into your home directory, if all you want to do is modify it. If not, the above should work. Again, I've not tried this, so I'm not sure.

tobiasw · 10-17-2006, 07:39 AM

No, with this option I still cannot create a file in the image. For example if I try to create a directory, I get the error message:
mkdir: cannot create directory 'test': Read-only file system

Thanks and regards
Tobias

pwc101 · 10-17-2006, 07:45 AM

hmmm... don't know then... sorry

unless you extract all the contents to a temp directory, and then remake the img file afterwards...?

tobiasw · 10-17-2006, 07:48 AM

... Good Idea..

How can I do this?
Is it afterwards the same img?

matthewg42 · 10-17-2006, 07:49 AM

squashfs is not designed to be modified. If you want to add a file to a squashfs, I think you have to extract the existing files to a regular filesystem, add your new file, and use the mksquashfs tool to generate a new .img file containing the old files and your new file.

See the squashfs howto for more info.

ethics · 10-17-2006, 08:16 AM

Quote:

Originally Posted by tobiasw

... Good Idea..

How can I do this?
Is it afterwards the same img?

No... it'll have a different amount of bits depending on what you edited...

What exactly are you trying to do?

tobiasw · 10-17-2006, 09:03 AM

Its an Internet Terminal, and I want to change some content of it...

Is there an easy way to install squashfs tool, it seems to be very advanced to install, like recompile kernel.. .

Thanks and regards

Tobias

pwc101 · 10-17-2006, 09:25 AM

I think you'd only need to install it if you wanted to create a new squashfs file afterwards. If you just wanted to stick it on a CD, I presume you could extract the contents using the cp command and then remake an iso from the extracted files.

I'd try running

Code:

yum search squashfs

to see if you've got anthing in your repositories that'll install it for you. It's been a while since I used fedora and yum, so that command might not be correct.

tobiasw · 10-17-2006, 02:53 PM

Hello,

I mounted now the r2.img in testdir, then copied the content with cp * -r in a new directory, changed the files and then created with
mksquashfs a new img file. Then I copied the img files to the Terminal, but after a while a get following error message:

SQUASHFS error: Unable to read page, block baa198b, size 97a7
Zlib_fs returned unexpected result 0xfffffffd
request module: runaway loop modeprobe binfmt_0000

What I did:

Code:

mount -o loop -t squashfs old.img tmpold
cd /tmpold
cp * -r ../test
cd ../test
mksquashfs etc home opt .. /home/new.img

mksquashfs version: 2.1R
Old files used version 2.0

Many thanks

Tobias

Freex · 10-17-2006, 03:43 PM

Can you clarify at what stage it goes wrong: The copying, the changing of the files or the creation of the new image?

aren't you supposed to put 'cp -r * <folder>' instead of 'cp * -r <folder>'? Also note that "if any directories are created by the cp command during the copying process, the newly created directory will have the same mode as the corresponding source directory." This means that if you use cp to make a new directory and the directory you copy from is read-only, the destination directory will also be read only, you have to do some chmod stuff to change that