CMSI 387
OPERATING SY S T E M S
Spring 2008
Assignment 0403
Here, finally, is the concrete assignment for getting your hands nice and dirty with the ext2 file system.
Not for Submission
For the current class material on process manage-
ment, read SGG Chapters 3–7. For this week, we
covered Chapters 3 and 4.
For Submission
The Short Version
Make an ext2 disk image, mount it, put some files
on it, print the user view of the file system (i.e., a
series of ls invocations), dump the disk image to
hex, print and annotate the dump, then turn in
your listings and annotated dump on hardcopy.
The Long Version
1. To create the disk image, you’ll need to learn
how to use the dd (“disk dump”) command.
The following example creates a new file called
image consisting of 1024 default-size blocks,
and initializes its contents with zeroes:
dd if=/dev/zero of=image count=1024
2. You should now have a file that is equivalent to
a brand-new, unformatted disk. “Format” it be
installing an empty ext2 file system on it:
mke2fs image
3. Mount the disk image — since this is typically a
privileged operation, Caskey has made “special
arrangments” for you to do this:
a. You can only do this on stewart.cs.lmu.edu.
b. To mount the disk image, use the special
mount-loop script in ~metropolis/sbin:
~metropolis/sbin/mount-loop image
c. This mounts the file system on /mnt/<your-
username>. To unmount, invoke:
~metropolis/sbin/umount-loop
d. That should do the trick; if these scripts
don’t work, let us know ASAP.
4. Create the following items within that mounted
file system:
a. A non-empty text file at the top-level di-
rectory of the file system
b. A directory at the top-level directory of the
file system
c. A second non-empty text file inside that
subdirectory (give it different content so
you can differentiate the two files)
d. A symbolic link inside that subdirectory to
the text file in the top-level directory
e. A hard link from the top-level directory to
the text file in the subdirectory
5. Run a series of ls commands on the now-
populated file system, and print the output.
Feel free to use various ls switches (e.g., -F, -l,
-a, -i, etc.) to show as much interesting informa-
tion as possible.
6. Dump the disk image file to hex via hexdump
-C, print out the hex dump, then annotate it to
identify these items:
a. The disk image’s superblock
b. The directory entries for the files, links, and
directories that you created
c. Where applicable, the inodes for the items
that you created
d. Where applicable, the data blocks occupied
by these items
How to Turn It In
Submit your file listings and annotated dump on
hardcopy. You may commit any of the digital arti-
facts you create to CVS if you wish, but for this
assignment I’ll focus on the hardcopy.