rename PDF files by their creation date (as determined by PDF metadata)

pdf-rename-by-cdate.sh

#!/usr/bin/env zsh -f
# Purpose: rename PDFs by their creation date
#
# From:	Timothy J. Luoma
# Mail:	luomat at gmail dot com
# Date:	2019-12-26

NAME="$0:t:r"

if [[ -e "$HOME/.path" ]]
then
	source "$HOME/.path"
else
	PATH="$HOME/scripts:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin"
fi

if ((! $+commands[pdfinfo] ))
then

		# note: if pdfinfo is a function or alias, it will come back not found
	echo "$NAME: 'pdfinfo' is required but not found in $PATH" >>/dev/stderr
	echo "if you use brew, you can install it via 'brew install poppler'" >>/dev/stderr
	exit 1
fi

for i in "$@"
do

	[[ ! -e "$i" ]] && echo "$NAME: '$i' does not exist." >>/dev/stderr && continue

	[ "$i:e:l" != "pdf" ] && echo "$NAME: '$i' is not a PDF." >>/dev/stderr && continue

		# make variable full path
	i=($i(:A))

		# note there are 3 spaces after -F' and before the second '
	CDATE=($(pdfinfo "$i" | awk -F'   ' '/^CreationDate:/{print $NF}'))

	[[ "$CDATE" == "" ]] && echo "$NAME: Unable to get CreationDate of '$i'." >>/dev/stderr && continue

	MONTH="$CDATE[2]"
	DAY="$CDATE[3]"
	YEAR="$CDATE[5]"

		# convert 1-digit day to 2-digit day
	case "$DAY" in
		1) DAY='01' ;;
		2) DAY='02' ;;
		3) DAY='03' ;;
		4) DAY='04' ;;
		5) DAY='05' ;;
		6) DAY='06' ;;
		7) DAY='07' ;;
		8) DAY='08' ;;
		9) DAY='09' ;;
	esac

		# convert month 3-letter-abbreviation to 2-digit month
	case "$MONTH" in
		Jan) MONTH='01' ;;
		Feb) MONTH='02' ;;
		Mar) MONTH='03' ;;
		Apr) MONTH='04' ;;
		May) MONTH='05' ;;
		Jun) MONTH='06' ;;
		Jul) MONTH='07' ;;
		Aug) MONTH='08' ;;
		Sep) MONTH='09' ;;
		Oct) MONTH='10' ;;
		Nov) MONTH='11' ;;
		Dec) MONTH='12' ;;
	esac

	# echo "'$i' was created on '${YEAR}-${MONTH}-${DAY}'."

	CDATE_FORMATTED="${YEAR}-${MONTH}-${DAY}"

	TEST_NAME=$(echo "$i" | sed "s#${CDATE_FORMATTED}##g")

	if [[ "$TEST_NAME" == "$i" ]]
	then

		# echo "Does not have date in it"

		SHORT="$i:t:r"

		DIR="$i:h"

		NEWNAME="$DIR/$SHORT ($CDATE_FORMATTED).pdf"

		COUNT='0'

			# if a file with that name already exists, add number to end of filename
		while [[ -e "$NEWNAME" ]]
		do
			((COUNT++))
			NEWNAME="$DIR/$SHORT ($CDATE_FORMATTED) $COUNT.pdf"
		done

		mv -vn "$i" "$NEWNAME"

	else

		echo "$NAME: '$i' already has the date in the filename."

	fi

done

exit 0
#EOF

Written to help answer this post in the Hazel forum.

#!/usr/bin/env zsh
set -f