git-annex/doc/tips/automatically_adding_metadata/pre-commit-annex

#!/bin/sh
#
# Copyright (C) 2014 Joey Hess <id@joeyh.name>
# Copyright (C) 2016 Klaus Ethgen <Klaus@Ethgen.ch>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This script can be used to add git-annex metadata to files when they're
# committed. It is typically installed as .git/hooks/pre-commit-annex
#
# You can also run this script by hand, passing it the names of files
# already checked into git-annex, and it will extract/refresh the git-annex
# metadata from the files.

tool="$(git config metadata.tool || :)"
if [ -z "$tool" ]; then
	tool=extract
fi
case "$tool" in
	exiftool)
		tool_exec="exiftool -unknown -zip -veryShort -ignoreMinorErrors -use MWG -dateFormat '%Y-%m-%dT%H:%M:%S'"
	;;
	*)
		tool_exec="$tool"
	;;
esac

extract_fields="$(git config metadata.extract || :)"
if [ -n "$extract_fields" ]; then
	tools=extract
	extract_want="^($(echo "$extract_fields" | sed -e 's/ /|/g' -e 's/_/ /g'))"
fi
exiftool_fields="$(git config metadata.exiftool || :)"
if [ -n "$exiftool_fields" ]; then
	tools="exiftool $tools"
	exiftool_want="^($(echo "$exiftool_fields" | sed -e 's/ /|/g' -e 's/_/ /g'))"
fi
if [ -z "$tools" ]; then
	exit 0
fi

case "$(git config --bool metadata.overwrite || :)" in
	true)
		equal="="
	;;
	*)
		equal="?="
	;;
esac

if git rev-parse --verify HEAD >/dev/null 2>&1; then
	against="HEAD"
else
	# Initial commit: diff against an empty tree object
	against="4b825dc642cb6eb9a060e54bf8d69288fbee4904"
fi

addmeta() {
	file="$1"
	field="$2"
	value="$3"
	afield="$(echo "$field" | tr ' ' '_')"
	git -c annex.alwayscommit=false annex metadata \
		--set "$afield$equal$value" --quiet -- "$file"
}

process() {
	if [ -e "$f" ]; then
		echo "adding metadata for $f"
		for tool in $tools; do
			case "$tool" in
				exiftool)
					tool_exec="exiftool -unknown -zip -veryShort -ignoreMinorErrors -use MWG -dateFormat '%Y-%m-%dT%H:%M:%S'"
				;;
				*)
					tool_exec="$tool"
				;;
			esac
			LC_ALL=C $tool_exec "./$f" | eval egrep --text -i \""\$${tool}_want"\" | while read line; do
				case "$tool" in
					extract)
						field="${line%% - *}"
						value="${line#* - }"
					;;
					exiftool)
						field="${line%%: *}"
						value="${line#*: }"
					;;
				esac
				
				if [ -n "$value" ]; then
					addmeta "$f" "$field" "$value"
				fi
			done
		done
	fi
}

if [ -n "$*" ]; then
	for f in "$@"; do
		process "$f"
	done
else
	git diff-index -z --name-only --cached $against | sed 's/\x00/\n/g' | while read f; do
		process "$f"
	done
fi