A Happy Friday post about fun one liners. Please post any one liners you have created that probably should have been a short shell script or any improvements for the below one liner. One improvement would be to get rid of the expr output.

Below was something I wrote just to quickly find if I had retired all the hosts that should have been retired from a txt file. I also used a slight variant of the code to check if DNS had been deleted.

UPDATE:
The reason for the expr was I has having problems nesting the if statements inside the backticks. After mcortese comment I updated the script to use an if statement outside of the backticks. RJC provided an alternative to backticks using posix compliant "$()". I have updated the script but did not nest the if statements which would be easier with "$()".

One Liner
for x in `grep KILL list.txt | awk '{ print $6 }'` ; do add=`host $x | grep -v NXDOMAIN | awk '{ print $4 }'` ; if [ "$add" ]; then ping -c1 -W1 $add >/dev/null; expr 1 / $? 2>/dev/null || echo $x ; fi ; done

Example txt from my file below. The servers were all local so I was able to reduce the timeout. In order for the above code to work you will need to be able to lookup the hostname and ping the ip returned:


Text File
KILL 300 62 running 10.200.5.25 woody.example.com
KILL 504 65 running 10.200.5.26 potato.example.org
     505 15 running 10.200.4.27 etch.example.net
KEEP 506 29 running 10.200.3.28 squeeze.example.co.uk
KILL 511 28 running 10.200.3.29 hamm.example.info
KILL 525 30 running 10.200.1.69 bo.example.xxx
KEEP 526 24 running 10.200.2.254 wheezy.example.tv

The Improved One Liner Based on Comments:
for x in $(awk '/KILL/{ print $6 }' /tmp/list.txt ) ; do add=$(host $x | awk '!/NXDOMAIN/{ print $4 }') ; if [ "$add" ]; then ping -c1 -W1 $add >/dev/null; res="$?"; fi; if [ "$res" -eq 0 ] ;then echo $x ; fi ; done