172.17.100.37 172.17.100.45 172.17.222.158

172.17.100.37
172.17.100.45
172.17.222.158

cmd = "grep -o '^[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}' /var/log/apache2/access.log | sort | uniq "

172.17.222.158 - - [30/Jan/2014:09:33:11 +0000] "GET /cgi-bin/right.cgi HTTP/1.1" 204  219 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.$
172.17.222.158 - - [30/Jan/2014:09:33:11 +0000] "GET /cgi-bin/stop.cgi HTTP/1.1" 204 218 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.0$
172.17.222.158 - - [30/Jan/2014:09:33:12 +0000] "GET /cgi-bin/right.cgi HTTP/1.1" 204 218 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.$
172.17.222.158 - - [30/Jan/2014:09:33:12 +0000] "GET /cgi-bin/stop.cgi HTTP/1.1" 204

echo "172.17.100.37 172.17.100.45 172.17.222.158" | tr ' ' 'n'
172.17.100.37
172.17.100.45
172.17.222.158

cat file
172.17.222.158 - - [30/Jan/2014:09:33:11 +0000] "GET /cgi-bin/right.cgi HTTP/1.1" 204  219 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.$
172.17.222.158 - - [30/Jan/2014:09:33:11 +0000] "GET /cgi-bin/stop.cgi HTTP/1.1" 204 218 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.0$
172.17.222.158 - - [30/Jan/2014:09:33:12 +0000] "GET /cgi-bin/right.cgi HTTP/1.1" 204 218 "http://172.17.223.72/index2.html?fname=172.17.223.75" "Mozilla/5.$
172.17.222.158 - - [30/Jan/2014:09:33:12 +0000] "GET /cgi-bin/stop.cgi HTTP/1.1" 204

awk -F/ '{print $8}' file
172.17.223.72
172.17.223.72
172.17.223.72