ubuntu input/output error

I'm having a problem with Ubuntu that I'm finding hard to troubleshoot for reasons that will become clear:

# reboot
-bash: /sbin/reboot: Input/output error
# dmesg
-bash: /bin/dmesg: Input/output error
# ps -e
ps: error while loading shared libraries: /lib/libproc-3.2.8.so: cannot read file data: Input/output error
# lsof
-bash: /usr/bin/lsof: Input/output error
# fsck
-bash: /sbin/fsck: Input/output error
# badblocks
-bash: /sbin/badblocks: Input/output error

So I can't see what is going on, and I can't remotely reboot. What can I do to get to the bottom of this?

Interestingly:

# init 0
Segmentation fault

I can cat /var/syslog but not /var/log/messages or several other important files. less and more don't work, neither do tail or head, etc.

The system is having severe trouble reading off of your hard disk. It's likely that the disk is dead (almost certain), but it could be something as simple as a loose/disconnected cable (don't count on it). There isn't anything you can do to troubleshoot it from here. Just power it off.

Check for loose connections on your hard disk. If everything is fine there boot from a rescue disk and run fsck or badblocks from there.

I hope you have a back up.

If you're using a VM it's quite likely that there was some interruption in the filesystem mounts, and linux switch the mounts to read only as a failsafe measure.

Unfortunately, it leaves your system practically unusable.

If you check /proc/mounts, and look for the root filesystem, there should be a line like this:

/dev/dm-0 / ext4 ro,relatime,errors=remount-ro,data=ordered 0 0

You'll see that the root filesystem has been mounted readonly.

Basically the only thing to do at this point (assuming this is the problem) is to reboot (via a KVM or other console power-off switch).