Time Converter

tc

#!/bin/bash

function unix_to_days_offset ()
{
  echo "($1-1356966000)/(24*3600)" | bc;
}

function unix_to_human ()
{
  res=`date -d @$1 "+%Y-%m-%d %H:%M:%S %Z"`;
  echo $res;
  unix_to_days_offset $1;
}

function human_to_unix ()
{
  res=`date -d $1 '+%s'`
  echo $res;
  unix_to_days_offset $res
}

function usage ()
{
  echo "Time converter"
  echo "  Converts between unix and human readable format date (like +%Y-%m-%d %H:%M:%S %Z)"
  echo "  Shows the number of days since 2013-01-01 00:00:00 JST"
  echo "  Note: It relies on GNU date command (Linux). It needs a trick to work on BSD's date (OSX)".
  echo "Usage:"
  echo "tc [seconds|date]"
  echo "examples:"
  echo "\$ tc 1375974000"
  echo ">   2013-08-09 00:00:00 JST"
  echo ">   220"
  echo "\$ tc 2013-08-09"
  echo ">   1375974000"
  echo ">   220"
}

# Bad usage
if [ "$#" -ne 1 ]; then
  usage
  exit 1
fi

# Help option
if [ $1 == -h ]; then
  usage
  exit 0;
fi

# Do the conversion
date -d @$1 >& /dev/null
if [ $? == 0 ]
then
  unix_to_human $1;
else
  human_to_unix $1;
fi

exit 0;