[OT] run command via ssh - problem

[Bill Davidsen]

Dan Track wrote:
> On Wed, Nov 4, 2009 at 1:33 PM, Bryn M. Reeves <bmr at redhat.com> wrote:
>> On Wed, 2009-11-04 at 13:13 +0000, Dan Track wrote:
>>> On Wed, Nov 4, 2009 at 1:10 PM, Dan Track <dan.track at gmail.com> wrote:
>>>> Hi,
>>>>
>>>> I'm running a command like this:
>>>>
>>>> for i in server1 server2;do ssh root@$i "`hostname`";done.
>>>>
>>>> However the hostname command always outputs the hostname of the server
>>>> that the above command is run from. I'd like to know how to run this
>>>> hostname command so that it actually runs on server 1, server2 etc..
>>>>
>>>> Thanks
>>>> Dan
>>>>
>>> Sorry just to add the actual script was like this:
>>>
>>> for i in server1 server2;do ssh root@$i "DNSNAME=\"basename
>>> \`hostname\`\";echo $DNSNAME";done
>> Not sure why you're setting a variable here but to have "basename" run
>> as a command and assign the output to DNSNAME you need to have basename
>> inside a pair of backticks too.
>>
>> You'll then hit another problem because you want to have nested
>> backticks (one pair for basename and another for hostname). Bash
>> supports '$()' as an alternative to backticks that does allow nesting -
>> writing $(hostname) is equivalent to `hostname` and allows you to write
>> $(basename $(hostname)).
>>
>> I'm not sure basename is going to do what you want here though - are you
>> looking for the short host name or the domain name? The basename command
>> separates components of a path based on the '/' (or whatever the system
>> defined path separator is). E.g.:
>>
>> $ DNS=$(basename $(hostname))
>> $ echo $DNS
>> breeves.fab.redhat.com
>>
>> If you just want the short hostname you can pass -s to hostname:
>>
>> $ ssh pe1950-1.gsslab hostname -s
>> pe1950-1
>>
>> Or the domain with -d:
>>
>> $ ssh pe1950-1.gsslab hostname -d
>> gsslab.fab.redhat.com
>>
>> Have a look at the man page for hostname for more options.
>>
>> Regards,
>> Bryn.
> 
> Hi Bryn,
> 
> Many thanks. I tried hostname -s but I keep getting the following:
> 
> hostname: Host name lookup failure
> 
> This may be because the hostname's are short already e.g just
> "server1" instead of "server1.example.com"
> 
> I've updated teh script to your recommendations but I still get the
> local hosts hostname in teh output instead of the remote servers
> hostname. Any other thoughts?
> 
> I now run the following:
> 
> for i in server1 server2;do ssh root@$i "DNSNAME=$(basename
> $(hostname)$);echo $DNSNAME";done
              A        A
              |        |
        what is that?  |
                       |
           need a backslash before the $
> 
> Thanks
> Dan
> 


-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot