A bash function for making it easy to change the access time of a file

atime_change_1month_ago is for making timestamps lie

#!/bin/bash
# (To change mtime instead of atime, switch the -a to -m)

atime_change_1month_ago()
{
  if [[ -e $1 ]]; then
    month=`date +%m`
    [ `echo $month|cut -c1` -eq 0 ] && month=`echo $month|cut -c2`
    month=$((month - 1))
    [ `expr length $month` -eq 1 ] && month="0$month"
    DayHrMin=`date +%d%H%M`
    touch -a -t ${month}${DayHrMin} "$1"
  else
    echo "$1: No such file or directory"
  fi
}