Shell Programming and Scripting

#! /usr/bin/ksh

#
# Initialize a few things

alias datecalc=./datecalc
MJan=1 MFeb=2 MMar=3 MApr=4 MMay=5 MJun=6
MJul=7 MAug=8 MSep=9 MOct=10 MNov=11 MDec=12

#
# Get current date and time and load into Now array removing leading zeros

set +A Now $(date '+%Y %m %e %k %M')
Now[1]=${Now[1]#0}
Now[4]=${Now[4]#0}
echo "Now = ${Now[0]} and ${Now[1]} and ${Now[2]} and ${Now[3]} and ${Now[4]}"

#
# Here is the timestamp
timestamp="Nov 3 11:04"

#
# Parse timestamp into the input array removing leading zeros from the numbers

IFS=": "
set +A input $(echo $timestamp)
input[2]=${input[2]#0}
input[3]=${input[3]#0}
echo "input = ${input[0]} and ${input[1]} and ${input[2]} and ${input[3]}"

#
# Load TS array with month, day, hour, and min of timestamp and remove leading zeros
# Guess the timestamp year

eval TS[1]=\$M${input[0]}
TS[2]=${input[1]}
TS[3]=${input[2]}
TS[4]=${input[3]}
(( ${TS[1]} > ${Now[1]} )) && ((TS[0]=${Now[0]}-1)) || TS[0]=${Now[0]}
echo "TS = ${TS[0]} and ${TS[1]} and ${TS[2]} and ${TS[3]} and ${TS[4]}"

#
#  Get number of days expressed as minutes
days=$(datecalc -a ${Now[0]} ${Now[1]} ${Now[2]} - ${TS[0]} ${TS[1]} ${TS[2]})
echo days = $days
((minutes = days * 60 * 24))
echo minutes = $minutes

#
#  Get the minutes past midnight for each date and then calc the delta
((MPM_Now=${Now[3]}*60+${Now[4]} ))
echo Now $MPM_Now ${Now[3]} ${Now[4]}
((MPM_TS=${TS[3]}*60+${TS[4]} ))
echo TS $MPM_TS ${TS[3]} ${TS[4]}
((MPM_delta=MPM_Now-MPM_TS))
echo delta = $MPM_delta

#
# Calc final answer
((minutes=minutes+MPM_delta))
echo And the answer is  that $timestamp was $minutes minutes ago
exit 0

$ ./tsdate
Now = 2006 and 11 and 6 and 13 and 13
input = Nov and 3 and 11 and 4
TS = 2006 and 11 and 3 and 11 and 4
days = 3
minutes = 4320
Now 793 13 13
TS 664 11 4
delta = 129
And the answer is that Nov 3 11 04 was 4449 minutes ago

Nov 3 11:04
Now = 2006 and 11 and 6 and 11 and 43
input = Nov and 3 and 11 and 4
TS = 2006 and 11 and 3 and 11 and 4
days = 3
minutes = 259200
Now 703 11 43
TS 664 11 4
delta = 39
And the answer is that Nov 3 11 04 was 259239 minutes ago