A Shell script to convert Unix Time to Human Readable Format and Vice Versa

gistfile1.sh

if echo {query} | grep -Gq '^[0-9]\{1,\}$'
then
	# Epoch to Human Readable Time Conversion
	date -r {query} -u "+%Y-%m-%d %H:%M:%S %Z"
elif echo {query} | grep -Gq '^[0-9]\{4\}-[0-9]\{1,2\}-[0-9]\{1,2\} [0-9]\{1,2\}:[0-9]\{1,2\}:[0-9]\{1,2\}$'
then
	# Human Readable to Epoch Time Conversion
	date -j -u -f "%Y-%m-%d %H:%M:%S" "{query}" "+%s"
else
	# Invalid Input
	echo "Use %Y-%m-%d %H:%M:%S"
fi

Added support to display Timezone when converting from epoch time