#!/bin/bash
# If you only want a cron job to run every-other-week
# you can use a method like this to track if it was
# run last week or not.

# Steve Parker, 2016
# Requires GNU date

# File to record when this was last run
lastrun=/tmp/last-run.txt

lastweek=`date +%G%V -d "now - 1 week"`
if [ "$lastweek" == "`cat $lastrun`" ]; then
  echo "Not running the main program; it was run last week"
  exit 0
else
  # Log that we ran this time
  date +%G%V > $lastrun
  /path/to/run-biweekly-program.sh
fi