iankelling.org Git - automated-distro-installer/blob - chost

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # chost: get canonical hostname
   5
   6 set -eE -o pipefail
   7 trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR
   8
   9 host=$1
  10 # ||: because if we are using 2+ resolvers, 1 may fail, causing error, but we still get
  11 # a valid address and we just use that
  12 addr=$(host $host | sed -rn 's/^\S+ has address //p;T;q' ||:)
  13 h=$(host $addr)
  14 case $h in
  15   *"no PTR record")
  16     echo "error: chost: $h" >&2
  17     exit 1
  18     ;;
  19 esac
  20 h=${h##* }
  21 # trailing dot in a hostname will mess up rsync
  22 h=${h%.}
  23 echo $h