Weird behavior of file permissions on mounted folder

jeff at smithicus.com jeff at smithicus.com
Thu Aug 4 22:38:06 UTC 2005


Okay, I'm out of my depth on this one. I have a network of 8
machines. Home directories are on the central server and are
mounted as /home on each of the workstations. So no matter what
machine I log into, I have EXACTLY the same user environment.

I have two different workstation machines that I've loaded with
Ubuntu 5.0.4. Let's call them FOO and BAR.

I logged into my account on the server and created a simple
little bash script called 'hello':

#!/bin/bash
echo "Hi there."

Of course, I made it executable (chmod a+x hello).

I can run it with this: ./hello 
and it prints out the 'Hi there message.'

Then I log into machine FOO. Run the same thing. It works just
dandy. 

Then I log into BAR. Run the same thing. I get this:
bash: ./echome: /bin/bash: bad interpreter: Permission denied

And it isn't just bash scripts. All executables in my home
directory fail to run.  Even ones I compile from scratch.
When I try to run a simple C-compiled hello-world I get this:
bash: ./hello2: Permission denied

In addition to mounting the /home directories from the server,
I'm also mapping the password and group records from the server
via NIS.

I've looked at the fstab for both FOO and BAR and yes indeed,
they are identical mount records. Same with /etc/passwd,
/etc/group and /etc/nsswitch.conf

When I first got things running a few days ago, machine BAR was
working just fine. But I've done something in the days since then
to break my permissions somehow. The only thing I can only think
of that might have been relevant is that I did a "sudo chown -R
jeffs:jeffs /home/jeffs" on BAR while I was tidying up some
root-owned files in my directory. I think it was around about
then that the misbehavior started, but I can't figure out what's
changed.

I realize that these kind of problems are probably very subtle
and highly dependant on my specific situation, but if somebody
can give me some hints about where to look it would help a lot.

Worst case, I'm going to have to reinstall Ubuntu on BAR again.
But I'll still have no idea what operation to avoid doing in the
future, so it's likely to happen again.

Thanks.
-- 
Jeff Smith
Computer Science Dept.
University of Saskatchewan
http://jefficus.usask.ca




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