2014-02-11



Since a long time, I think, that Unix is missing  a  clever  date
arithmetic  tool, such as bc(1). At least calculating the differ-
ences of two dates should be easy. To fill this gap,  I  wrote  a
rudimentary, but better-than-nothing tool, called `datediff'.  It
can print the difference in years, months (30 days! :-( ), weeks,
days, hours, minutes, and of course seconds.

The script is a quick hack. It's main shortcoming is  the  30-day
month. Nonetheless, the script is already helpful.

     #!/bin/sh

     if [ $# -lt 2 ] ; then
             echo "Usage: ${0##*/} -YmWdHMS date1 [date2]" >&2
             exit 1
     fi

     d1=`date +%s -d "$2"`
     if [ $# -eq 3 ] ; then
             d2=`date +%s -d "$3"`
     else
             d2=`date +%s`
     fi

     diff=`expr "$d2" - "$d1"`

     case "$1" in
     -Y)     echo `expr $diff / 60 / 60 / 24 / 365` years ;;
     -m)     echo `expr $diff / 60 / 60 / 24 / 30` months ;; # FIXME
     -W)     echo `expr $diff / 60 / 60 / 24 / 7` weeks ;;
     -d)     echo `expr $diff / 60 / 60 / 24` days ;;
     -H)     echo `expr $diff / 60 / 60` hours ;;
     -M)     echo `expr $diff / 60` minutes ;;
     -S|*)   echo $diff seconds ;;
     esac



http://marmaro.de/lue/        markus schnalke <meillo@marmaro.de>