bash functions

# A simple function to blow up the list of hosts (by A record only, no CNAMEs)
# and spit them out in a simple pair to be consumed by other scripts. If the
# name given has no A records, nothing will output.  If an A record has no 
# corresponding PTR, the IP will be placed in the name field.
name_expand() {
  if [ -z "$1" ] ; then
    echo usage: name_expand hostname
    return 1
  fi

  ip_list=$(dig +short $1 A | grep -v '^;')
  for ip in $ip_list ; do
    host=$(dig +short -x $ip)
    if [ -z "$host" ] ; then
      host=$ip
    fi
    echo "$host $ip"
  done
}

# Uses name_expand, and adds a ping Round-Trip time (single ping) for each line
ping_expand() {
  if [ -z "$1" ] ; then
    echo usage: ping_expand hostname
    return 1
  fi
   
  # Expand name into a list of IPs
  ip_list=$(name_expand $1)
  OLD_IFS=$IFS
  IFS=$'\n'
  for line in $ip_list ; do
    ip=$(echo $line | cut -f 2 -d ' ')
    rtt=$(ping -q -c 1 $ip | grep '^round-trip' | cut -d ' ' -f 4 | cut -d '/' -f 1)
    echo "$line $rtt"
  done
  IFS=$OLD_IFS
}

# Ping a list of hosts
ping_list() {
  hosts=$*
  for host in $hosts ; do
    rtt=$(ping -q -c 1 $host | grep '^round-trip' | cut -d ' ' -f 4 | cut -d '/' -f 1)
    echo "$host $rtt"
  done
}