Re: problem with tail -f that need to add to each line constant string at the beginning of each line

[dan12341234]

Thanks Bob

this solution is great.

Dan  


Bob Proulx wrote:
> 
> dan12341234 wrote:
>> im running 4 scripts that perform ssh and tail -f on a file exist on 4
>> servers and display on the screen.
>> (1 script per servers)
>> 
>> ssh server1 tail -f /var/log/apache/access_log
>> ssh server2 tail -f /var/log/apache/access_log
>> ssh server3 tail -f /var/log/apache/access_log
>> ssh server4 tail -f /var/log/apache/access_log
>> 
>> the problem is that the display dosent show any identification from which
>> server each line
>> 
>> what i need is something with an echo servername, before each line
>> printed
>> to the screen
> 
> There are many specialized programs to do exactly what you are asking
> such as dsh (distributed shell) and other tools.  You might want to
> investigate those.
> 
> But you can do what you want by using sed to prepend to the line.
> 
>   ssh -n server1 'tail -f /var/log/syslog | sed --unbuffered
> "s/^/$(hostname): /"'
>   ssh -n server2 'tail -f /var/log/syslog | sed --unbuffered
> "s/^/$(hostname): /"'
> 
> You might consider applying the commands as standard input instead.  I
> think it is easier to avoid quoting problems that way.
> 
>   echo 'tail -f /var/log/syslog | sed --unbuffered "s/^/$(hostname): /"' |
> ssh -T server1
> 
> Bob
> 
> 
> 

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