#!/bin/ksh
#timediff - A simple time difference routine
#Requires input of two times (format hh:mm:ss) on command line or will prompt.
#
#Author:- Robin

if [ $# -eq 2 -o $# -eq 3 ]
then
   stime=$1                      # Start time
   etime=$2                      # End time
else
   read stime?"Please enter the start time: "
   read etime?"Please enter the end time: "
   read response?"Respond in hh:mm:ss or seconds? (h/S)"
   typeset -l response
   if [ "$response" = "h" ]
   then
      set - "" "" hh:mm:ss       # Force parm 3 to be hh:mm:ss for later
   fi
   echo "The difference is: \c"  # Write a tag just for interactive use
fi

echo $stime|tr ":" " "|read shh smm sss        # Split the time up
echo $etime|tr ":" " "|read ehh emm ess

((shhs=$shh*3600))
((ehhs=$ehh*3600))
((smms=$smm*60))
((emms=$emm*60))

((ssecs=$shhs+$smms+$sss))
((esecs=$ehhs+$emms+$ess))

((delta=$esecs-$ssecs))
if [ $delta -lt 0 ]                # Is difference negative, i.e. we're past midnight
then
   ((delta=$delta+86400))          # Add a day's worth of seconds
fi

if [ "$3" = "hh:mm:ss" ]           # is parm 3 set to request formatted output
then
   typeset -Z2 dhh dmm dss
   ((dhh=$delta/3600))               # Use integer match to get whole hours
   ((delta=$delta-(3600*$dhh)))  # Take off enough seconds to compensate
   ((dmm=$delta/60))            # use integer matsh to get whole minutes
   ((dss=$delta-(60*$dmm)))  # Take off enough seconds to compensate
   echo "$dhh:$dmm:$dss"
else
   echo $delta           # Show total seconds difference
fi

#!/bin/ksh
preval=""

cat myfile |while read label val
do
   if $preval != "" ]
   then
      echo "$label is after `timediff $preval $val`"
      preval=$val
   fi
done

echo "$label is after `timediff $preval $val hh:mm:ss`"