Shell Script 050-set-date.sh

#!/bin/sh
# setdate - friendly front-end to the date command

# Date wants: [[[[[cc]yy]mm]dd]hh]mm[.ss]

askvalue()
{
  # $1 = field name, $2 = default value, $3 = max value,
  # $4 = required char/digit length

  echo -n "$1 [$2] : "
  read answer
  if [ ${answer:=$2} -gt $3 ] ; then
    echo "$0: $1 $answer is invalid"; exit 0
  elif [ "$(( $(echo $answer | wc -c) - 1 ))" -lt $4 ] ; then
    echo "$0: $1 $answer is too short: please specify $4 digits"; exit 0
  fi
  eval $1=$answer
}

eval $(date "+nyear=%Y nmon=%m nday=%d nhr=%H nmin=%M")

askvalue year $nyear 3000 4
askvalue month $nmon 12 2
askvalue day $nday 31 2
askvalue hour $nhr 24 2
askvalue minute $nmin 59 2

squished="$year$month$day$hour$minute"
# or, if you're running a Linux system:
# squished="$month$day$hour$minute$year"

echo "Setting date to $squished. You might need to enter your sudo password:"
sudo date $squished

exit 0