A little script to tell you the days between two YYYYMMDD dates: #!/bin/bash function usage { echo "date {date} {date}, where date is in the format YYYYMMDD" } function absolute_value { echo $1 | sed s/-// } # Print help, if number of args wrong if [ -z $2 ] then usage 1>&2 exit 1 fi if [ $3 ] then usage 1>&2 exit 1 fi # The dates we want to days between DATE_ONE="$1" DATE_TWO="$2" # provide the original date instead of "now" and ask for "seconds since epoch" DATE_ONE_EPOCH=$(date -d "${DATE_ONE}" "+%s") DATE_TWO_EPOCH=$(date -d "${DATE_TWO}" "+%s") #Math DAYS=$(($((${DATE_ONE_EPOCH} - ${DATE_TWO_EPOCH}))/$((60*60*24)))) absolute_value $DAYS ------ Note the unmath in "absolute_value" ;-)
Systems, tools, and observations.