[Novalug] Re: [Ma-linux] backup/mirror script

[Angelo Bertolli]

Mark Smith wrote:
> okay.
>
> On Mon, Apr 16, 2007 at 08:59:10PM -0400, Angelo Bertolli wrote:
>   
>> if [ "$ip" != "" ]
>> then
>>   if nc -v -z -w $timeout $ip $port
>>   then
>>      mkdir -p $dest/$host
>>      rsync $ropts --exclude-from $exfile $ip:/ $dest/$host/
>>   else
>>      echo "Usage: $usage"
>>      exit -1
>>   fi
>> elif [ "$host" != "" ]
>> then
>>   if nc -v -z -w $timeout $host $port
>>   then
>>      mkdir -p $dest/$host
>>      rsync $ropts --exclude-from $exfile $host:/ $dest/$host/
>>   else
>>      echo "Usage: $usage"
>>      exit -1
>>   fi
>>     
>
> you've repeated the same logic twice, once using ip and once
> using host.  try and avoid that whenver possible and it's
> definitely possible here.
>   

If I included an IP address, I wanted to use the IP address for rsync, 
but still HOST for the location.  (This is useful for machines that I 
have running on DHCP.)  Otherwise, with just host name, use the host 
name for rsync.  There's probably a nicer way to do this by setting the 
IP variable from HOST ahead of time or something.

> why are you testing the connection with nc when rsync will
> do that as a matter of course anyway?  it complicate things
> unnecessarily and doesn't help.
>   

I don't like the way rsync fails.  Especially since I have a firewall 
rule that I use that drops packets if someone connects to ssh too 
frequently.  Rsync ends up taking forever to find out it can't connect.

> don't exit -1 as that's "weird".  the desired range is 0-255.
> if you want 255, use 255, but i would suggest 'exit 1' for
> "normal failure" or 2 if you want differentiate that between
> a usage statement, or pick your exit code.
>   

Are there any standard numbers I should use?  Like 5 means missing 
arguments or something?

> the rsync exit code is lost.  this will have the affect that
> your program may generate errors and then exit successfully
> (e.g. exit 0) which is probably not want you want.
>   

Yeah :(  I really need to do more error checking.

> when rsync runs, you're losing filesystem information where
> you traverse mount points.  that is to say, if the original
> host has multiple filesystem points, the target will not.
>   

Yes, that's true.  So far it hasn't been a problem for me, since I can 
go into fstab to recreate partitions.  But do you think it's a problem 
in general, or that I need to exclude /media/* and /mnt/* so it never 
picks up things that are mounted?  Actually that might to be a good 
solution because there may be things under /mnt that I want.

> the script should be run as root to get an accurate representation
> of the original disk.  certain modes will not be copied, ownership
> will get lost, and you won't be able to open certain files as a
> regular user.
>   

Ok, so I should really test to see if you are root when you do this.  
That's another good error to catch.

> make sure it's running as ssh (if applicable) to protect privacy
> enroute.
>   

I think this is the default for rsync.

> if this is a script that will run in an unattended mode you'll
> need to open ssh for root w/o a password from the remote side.
> you'll need to take necessary precautions and accept certain
> risk with that.
>
> your script can probably be better written by shortening a lot
> and checking codes (or passing to user).
>   


Thanks for the comments.  I actually do use this at the command line, 
and not unattended.  Call me crazy, but I'm not too keen on using ssh 
keys with root.

Angelo