now.sh

#!/bin/sh

# Print the current time and how far we are along the day, week and year.
# https://twitter.com/tmcw/status/239516909450711040
# https://gist.github.com/3472701
# https://gist.github.com/3474085

# Tom actually wants to see how much of his life is left.
# https://twitter.com/tmcw/status/239603708973957120

# Set your birthday.
BIRTHDAY='March 30'
BIRTHYEAR=1990

# Boundaries of the week
day_start=$(date --date=12:00am +%s)
day_end=$(date --date='tomorrow 12:00am' +%s)

# Boundaries of the day
if [ $(date +%A) = 'Sunday' ]
  then
  week_start=$day_start
  week_end=$(date --date='next sunday 12am' +%s)
else
  week_start=$(date --date="last Sunday 12:00am" +%s)
  week_end=$(date --date="Sunday 12:00am" +%s)
fi

# Boundaries of the year
year_start=$(date --date='January 1' +%s)
year_end=$(date --date="January 1, $(( $(date +%Y) + 1 ))" +%s)

# Boundaries of the expected life
life_start=$(date --date="$BIRTHDAY, $BIRTHYEAR" +%s)

# US males are expected to live to about 75.6
# http://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy

# Here's some idea of the variance.
# http://qcpages.qc.cuny.edu/~redwards/Papers/edwards-lifetables.pdf

# Let's take
#   50 as a low estimate,
#   100 as a high estimate and
#   75 as the expectation
life_end_early=$(date --date="$BIRTHDAY, $(( 50 + $BIRTHYEAR))" +%s)
life_end_expected=$(date --date="$BIRTHDAY, $(( 75 + $BIRTHYEAR))" +%s)
life_end_late=$(date --date="$BIRTHDAY, $(( 100 + $BIRTHYEAR))" +%s)

# Proportion of time passed
prop_time() {
  start=$1
  end=$2
  difference=$(( $end - $start ))
  so_far=$(( $(date +%s) - $start ))
  echo $(( 100 * $so_far / $difference ))
}

day_percent=$(prop_time $day_start $day_end)
week_percent=$(prop_time $week_start $week_end)
year_percent=$(prop_time $year_start $year_end)
life_percent_early=$(prop_time $life_start $life_end_early)
life_percent_expected=$(prop_time $life_start $life_end_expected)
life_percent_late=$(prop_time $life_start $life_end_late)

# Pretty printing
printf '\033[36m%s\033[0m        Today: %02d%%          This week: %02d%%       This year: %02d%%\n' \
  $(date +'%I:%m%p'| tr '[APM]' '[apm]') $day_percent $week_percent $year_percent
printf           '          Life (low): %02d%%    Life (expected): %02d%%     Life (high): %02d%% \n' \
  $life_percent_early $life_percent_expected $life_percent_late