[NTLUG:Discuss] Bash Scripting and permissions

[kbrannen@gte.net]

Patrick Parks wrote:
> I am working on a simple bash script, that will tar and zip my home dir 
> onto a remote backup computer across nfs. On the backup computer in the
> /etc/exports file the permissions for the share that is exported to nfs
> is using the defaults, the root_squash. I would like to keep this as is
> if possible, for security. Now back to my script. My script checks to
> see if the directory is mounted before trying to tar then zip the file
> to it.If it is not mounted, it then attempts to mount it. This is where
> the problem comes in. In order to mount the nfs directory, I must be
> root. If I run the script as root, when it gets to the part about
> copying the files to the remote mounted nfs drive, it does not let me
> copy, cause I am root, and the root_squash is on   in the exports
> permissions. As I am writing this I am getting some ideas :) Can a user
> have permissions to mount a remote nfs directory without having to sudo?
> That may be my answer there, off to the search engines to see if this
> will work, would appreciate any suggestions. Thanks

Use 2 scripts (programs).  Have 1 program that all it does is [un]mount the 
NFS dir, and the other script to do all the other work.  Something like this:

#!/bin/bash
# mount as root
/usr/local/bin/mountnfs /backup
# backup
tar -czvf /backup/`date`.tgz /home
# unmount as root
/usr/local/bin/mountnfs -u /backup

So the script above is the controlling script and makes the calls to the other 
program to do the "special" work; and the mountnfs script you write should be 
able to do nothing other than mount and umount (or you could use sudo as you 
imply).

HTH,
Kevin