#!/bin/bash
#
if [ $# -lt 2 ]; then
  echo "Usage: $0 <Host file> <Command> [sleep time]"
  echo "Host file contains the list of hosts to open screen session for"
  echo "Command is the command to execute on each screen session"
  echo "First time use init as Command to construct the screens"
  exit 1
fi
#
# Get a list (say server names)
HOSTFILE=$1
# Create a counter for the screen windows
HOSTCMD=$2
# Number of seconds to sleep
if [ -z "$3" ]; then
  SLEEPTIME="0.2"
else
  SLEEPTIME=$3
fi
#if ! [[ "$SLEEPTIME" =~ ^[0-9]+$ ]]; then
#  SLEEPTIME=0
#fi
#echo $SLEEPTIME
#exit
# Define a name for the screen session.
SCRNAME='thenag'
NOW=$(date +"%Y-%m-%d-%H-%M-%S")
TMPFILE="/tmp/${SCRNAME}-${NOW}.txt"
#
if [ ! -f "$HOSTFILE" ]; then
  echo "File: $HOSTFILE does not exist"
  exit 1
fi
#
if [ "$HOSTCMD" == "init" ]; then
  echo "Initializing Screens ..."
fi
#

if [ "$HOSTCMD" == "quit" ]; then
  echo "Quitting Screens ..."
  screen -S $SCRNAME -X quit
  exit
fi

declare sn integer
sn=0
cat $HOSTFILE | while read ServerName
do
  let sn++
  echo "Processing $ServerName, Sequence $sn"
  case $HOSTCMD in
    init)
      # This creates a blank screen window for each instance
      screen -S $SCRNAME -X screen
      # Sleep may be required as sometimes commands get missed!
      sleep $SLEEPTIME
      screen -S $SCRNAME -p $sn -X stuff "echo $ServerName \n"
      ;;
    ssh)
      screen -S $SCRNAME -p $sn -X stuff "ssh ${ServerName}\n"
      sleep $SLEEPTIME
      ;;
    tail)
      screen -S $SCRNAME -p $sn -X hardcopy $TMPFILE
      sleep $SLEEPTIME
      sed -e :a -e '/^\n*$/{$d;N;};/\n$/ba' $TMPFILE
      tail -3 $TMPFILE
      rm $TMPFILE
      echo "--------------------------------"
      ;;
    *)
      screen -S $SCRNAME -p $sn -X stuff "${HOSTCMD} \n"
      sleep $SLEEPTIME
  esac

done