contrib/isc-dhcp/contrib/sethostname.sh

   1 #!/bin/sh
   2
   3 # This script can be installed in /etc/dhclient-enter-hooks to set the client's
   4 # hostname based either on the hostname that the DHCP server supplied or the
   5 # hostname in whatever ptr record exists for the assigned IP address.
   6
   7 if [ x$new_host_name = x ]; then
   8   ptrname=`echo $new_ip_address \
   9            |sed -e \
  10   's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\)/\4.\3.\2.\1.in-addr.arpa/'`
  11   (echo "set type=ptr"; echo "$ptrname") |nslookup >/tmp/nslookup.$$
  12   set `sed -n -e "s/$ptrname[   ]*\(canonical \)*name *= *\(.*\)/\2 \1/p" \
  13                                                         < /tmp/nslookup.$$` _
  14   if [ x$1 = x_ ]; then
  15     new_host_name=""
  16   else
  17     if [ $# -gt 1 ] && [ x$2 = xcanonical ]; then
  18       new_host_name=`sed -n -e "s/$1[   ]*name *= *\(.*\)/\1/p" \
  19                                                         </tmp/nslookup.$$`
  20     else
  21       new_host_name=$1
  22     fi
  23   fi
  24   rm /tmp/nslookup.$$
  25 fi
  26 if [ x$new_host_name != x ]; then
  27   hostname $new_host_name
  28 fi
  29