Shell Programming and Scripting

date -d "2007-09-01 17:30:40" '+%s'

date: illegal option -- d
Usage: date [-u] [+Field Descriptors]

echo "$(date +'%s' -d 2007-09-02)/86400"-"$(date +'%s' -d 2007-09-01)"/86400 | bc

echo $(date --date='2007-09-01 17:30:00' +%s)/60-$(date --date='2007-09-01 18:30:00' +%s)/60 | bc

echo "$(date +'%s' -d 2007-09-02)/86400"-"$(date +'%s' -d 2007-09-01)"/86400 | bc
Invalid character in date/time specification.
Usage: date [-u] [+Field Descriptors]
Invalid character in date/time specification.
Usage: date [-u] [+Field Descriptors]
syntax error on line 1 stdin

use DateTime;
$dt = DateTime->new( year => 1974, month => 11, day => 30, hour => 13, minute => 30,      second => 0, nanosecond => 500000000, time_zone => 'Asia/Taipei' ); 
$epoch_time  = $dt->epoch;

epoc=$(printf "%(%s)T" "2010-10-24 00:00:00")

oifs="$IFS"  
JulianDate() 
{  
IFS="-"  
array=($1)  
IFS="$oifs"  
scale=0  
d=${array[2]}  
m=${array[1]}  
y=${array[0]} 
echo $((d-32075+1461*(y+4800+(m-14)/12)/4+367*(m-2-(m-14)/12*12)/12-3*((y+4900+(y-14)/12)/100)/4 )) 
}  

fromdate=$( JulianDate 2011-04-01 ) 
# ISO yyyy-mm-dd 
todate=$( JulianDate 2011-05-04 )  
diff=$((todate - fromdate)) 
echo $diff

$ perl -e 'use Time::Local; print timelocal(0,0,0,$ARGV[2], $ARGV[1]-1, $ARGV[0]);' 2007 09 01
1188568800