epoch - detect and print time value in various bases (ns us ms s) and format it as local and utc date

epoch.sh

#!/bin/bash

#FORMAT="--iso-8601=ns"
FORMAT="+%Y-%m-%d %H:%M:%S"
TZ=`date ${UTC} +%z`

NANO=1000000000
MICRO=1000000
MILLI=1000
MIN_SECONDS=1000000000

if [[ $1 == "-l" ]]; then
	shift
   # could be an utc/local argument
fi

VAL=$1

function dateFromSeconds {
	S=$1
   SUB=$2
   
   FORMAT_SUFFIX=
   if [[ -n $SUB ]]; then
   	FORMAT_SUFFIX=".${SUB}"
   fi
   
	date --utc "${FORMAT}${FORMAT_SUFFIX} %z" --date "@${S}"
	echo
	date "${FORMAT}${FORMAT_SUFFIX} %z" --date "@${S}"
}

function maskUpper {
	VAL=$1
	PREC=$2
   echo $(($VAL / $PREC))
}

function maskLower {
	VAL=$1
	PREC=$2
   SECONDS_PART=$((($VAL / $PREC) * $PREC))
   echo $(($VAL - $SECONDS_PART))
}

function printVariants {
	VAL=$1
   PREC=$2
	IN_NANOS=`echo "scale=9; $VAL / ($PREC / $NANO)" | bc`
	IN_MICROS=`echo "scale=9; $VAL / ($PREC / $MICRO)" | bc`
	IN_MILLIS=`echo "scale=9; $VAL / ($PREC / $MILLI)" | bc`
	IN_SECONDS=`echo "scale=9; $VAL / $PREC" | bc`
	printf "%.0f ns\n%.3f us\n%.6f ms\n%.9f s" "$IN_NANOS" "$IN_MICROS" "$IN_MILLIS" "$IN_SECONDS"
	#printf "%.0fns %.3fus %.6fms %.9fs" "1.0" "0.001" "0.000001" "0.000000001"
}

function fromNanos {
	N=$1
   printVariants $N $NANO
	echo -e "\n"
	SECONDS=`maskUpper $N $NANO`
   NANOS_ONLY=`maskLower $N $NANO`
   NANOS_FORMATTED=`printf "%09dns" "$NANOS_ONLY"`
   dateFromSeconds $SECONDS $NANOS_FORMATTED
   echo -e "\nSubseconds:\n"
   printVariants $NANOS_ONLY $NANO
	echo
}

function fromMicros {
	N=$1
   printVariants $N $MICRO
	echo -e "\n"
	SECONDS=`maskUpper $N $MICRO`
   MICROS_ONLY=`maskLower $N $MICRO`
   MICROS_FORMATTED=`printf "%06dus" "$MICROS_ONLY"`
   dateFromSeconds $SECONDS $MICROS_FORMATTED
   echo -e "\nSubseconds:\n"
   printVariants $MICROS_ONLY $MICRO
	echo
}

function fromMillis {
	N=$1
   printVariants $N $MILLI
	echo -e "\n"
	SECONDS=`maskUpper $N $MILLI`
   MILLIS_ONLY=`maskLower $N $MILLI`
   MILLIS_FORMATTED=`printf "%03dms" "$MILLIS_ONLY"`
   dateFromSeconds $SECONDS $MILLIS_FORMATTED
   echo -e "\nSubseconds:\n"
   printVariants $MILLIS_ONLY $MILLI
	echo
}

function fromSeconds {
	SECONDS=$1
   printVariants $SECONDS 1
	echo -e "\n"
   dateFromSeconds $SECONDS
	echo
}

if [[ $VAL -gt $(($MIN_SECONDS * $NANO)) ]]; then
  fromNanos $VAL
elif [[ $VAL -gt $(($MIN_SECONDS * $MICRO)) ]]; then
  fromMicros $VAL
elif [[ $VAL -gt $(($MIN_SECONDS * $MILLI)) ]]; then
  fromMillis $VAL
elif [[ $VAL -gt $MIN_SECONDS ]]; then
  fromSeconds $VAL
else
  printVariants $VAL 1
fi